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Objective: Netherton syndrome (NS) is a rare hereditary dermatosis, and the correlation between genotype and phenotype in this disease warrants further investigation. This study aimed to explore the genotype-phenotype correlation in NS. Methods: We collect cases from our clinic and relevant literature. After rigorous screening, we included 162 patients with NS-associated symptoms and SPINK5 mutations. We characterized the distribution and mutation types of allele variants. Logistic regression was employed to analyze the correlation between the location of these variants and phenotypes. Additionally, the association between the homozygous condition of variants and death during infancy was analyzed using the Chi-square test. Results: Among 162 patients, we identified 324 allele variants, comprising 75 different mutations. Of these, 73 patients carried heterozygous variants, while 89 patients had homozygous variants. We observed that patients with variants or homozygous variants located in the 5′ half of the gene were more likely to experience failure to thrive (P < 0.05). Similarly, variants or homozygous variants located outside DomainR-5 were also associated with an increased risk of failure to thrive (P < 0.05). Furthermore, variants in domain regions were significantly correlated with the presence of ichthyosis linearis circumflexa (P < 0.01). Patients with homozygous fatal variants (c.153delT, c.1431-12G>A, c.1111C>T, c. 1887 + 1G>A, and c. 995delT) had a higher likelihood of mortality during infancy (P < 0.001). Conclusion: Our study provides valuable insights into the genotype-phenotype correlation in Netherton syndrome, enhancing our understanding of the disease and potentially informing the development of future therapeutic approaches. [ABSTRACT FROM AUTHOR]

Familial Mediterranean Fever (FMF) is a hereditary autoinflammatory disorder, particularly present in the Mediterranean populations, and associated with pathogenic variants in the MEFV gene. This study aims to investigate the distribution of MEFV variants in a large cohort of Lebanese patients, and to explore the genotype-phenotype correlation among affected individuals. A retrospective analysis was conducted on 3,167 patients referred for MEFV sequencing at the Medical Genetics and Genomics Center(CGGM) at Saint-Joseph University of Beirut-Lebanon, from 2006 to 2023. Sanger sequencing was used to detect MEFV variants, focusing initially on hot-spot exons. Among the 3,167 patients, 46.73% (N = 1,480) carried at least one MEFV variant. The most common variants detected were M694V and V726A, both found in 28.98% of cases, followed by E148Q(27.83%) and M694I(13.98%). Moreover, Shiites and Sunni Muslims, and individuals from South and North Lebanon exhibited the highest frequency of variants. Interestingly, family history was found to be significantly higher in patients having two MEFV variants than those with one variant (p = 0.0026). The most commonly reported symptoms were fever(78%), abdominal pain(88%), joint pain(65%), and thoracic pain(46%). The genotype-phenotype correlation analysis revealed a more severe phenotype in patients carrying the M694V or V726A mutations compared to those with the homozygous E148Q genotype. This study, the largest in Lebanon, highlights the high prevalence of MEFV variants, particularly M694V and V726A, in FMF patients. Our data provide valuable insights into the genetic landscape of FMF in Lebanon and emphasize the importance of early genetic screening for a better disease management and genetic counselling. [ABSTRACT FROM AUTHOR]

Background/Objectives: A heterozygous mutation in the WFS1 gene is responsible for autosomal dominant non-syndromic hearing loss (DFNA6/14/38) and Wolfram-like syndrome, which is characterized by bilateral sensorineural hearing loss with optic atrophy and/or diabetes mellitus. However, detailed clinical features for the patients with the heterozygous p.A684V variant remain unknown. Methods: We report the clinical details of 14 cases with a heterozygous p.A684V variant in the WFS1 gene identified from target resequencing analysis of 63 previously reported deafness genes by next-generation sequencing of 15,684 hearing loss patients (mean age 27.5 ± 23.1 years old, 6574 male, 8612 female and 498 for whom information was unavailable). Results: Among the 14 patients from 13 families with the p.A684V variant, nine were sporadic cases. In addition, we confirmed de novo occurrence of this variant in seven families. This result strongly supports the notion that this variant was located on a mutational hotspot. When comparing previously reported cases of autosomal dominant WFS1 gene-associated hearing loss, most of the patients in this study showed severe-to-profound bilateral sensorineural hearing loss (genotype–phenotype correlation). Two patients had optic atrophy, while the others did not have any other complications. Conclusions: The identified heterozygous p.A684V variant appears to be a hotspot mutation and likely to cause severe-to-profound hearing loss in early childhood. Cochlear implantation is considered favorable in cases of hearing impairment due to this variant. [ABSTRACT FROM AUTHOR]

Background/Objectives: X-linked hypophosphataemic rickets (XLH) represents the most frequent type of rickets from genetic origin, it is caused by mutations on the PHEX gene. The main clinical manifestations are short stature and bone deformities. Phenotype variation is observed at the intrafamily and interfamily level. The bases for this variation are not fully understood. The aim of this study was to investigate if there is a phenotype–genotype correlation in a cohort of patients with confirmed diagnosis of XLH. Methods: We recruited a total of 130 patients of Mexican Mestizo origin with confirmed molecular diagnosis of XLH; this is one of the largest cohorts reported. Results: Radiographies for calculating the rickets severity score (RSS) were available from 50 patients. A total of 56 different pathogenic variants were found among the study population; from them, 31 variants have not been previously reported. We compared the RSS values between individuals considering clinical and biochemical characteristics such as age, height, sex, phosphorus, and alkaline phosphatase in serum; no significant differences were observed. Then, we compared the RSS considering if the variant was intronic or exonic and considering the presence of a truncated protein or not. None of the two comparisons showed significant differences. Conclusions: We did not find a genotype–phenotype correlation in the study population. Despite the knowledge regarding the genetic cause of XLH, the mechanisms driving the intrafamily and interfamily variability remain elusive. More analyses looking for the genotype–phenotype correlation are necessary in other populations, especially considering the discovery of new mutations in patients from different origin. [ABSTRACT FROM AUTHOR]

3 M syndrome is a well-known autosomal recessive skeletal genetic disorder caused by biallelic pathogenic variants in the CUL7, OBSL1, and CCDC8 genes. Affected individuals exhibit profound pre- and postnatal growth retardation, distinctive facial features with normal intelligence. This study aims to provide insight into the comprehensive evaluation of clinical, laboratory, and radiological findings, expand the mutational spectrum of the disease, and establish a genotype–phenotype correlation in the present cases. A total of 25 patients from 19 unrelated families were included in the study. Genetic etiology was determined in probands through the utilization of Sanger sequencing and/or targeted gene panel analysis. The clinical, laboratory, and genetic features of all patients at admission and during follow-up were documented. Genotype–phenotype correlation was carried out in the CUL7 and OBSL1 groups. The genetic etiology was established in all patients (n = 25/25, 100%). We identified 15 distinct variants in CUL7, OBSL1, and CCDC8 genes, with eleven being novel. CUL7 variants were present in 13 patients (n = 13/25, 52%), while OBSL1 variants were found in 11 patients (n = 11/25, 44%). No notable distinctions were found in mean birth weight, height, and standard deviation scores between the CUL7 and OBSL1 mutation groups (p > 0.05). Patients with CUL7 variants exhibited significantly lower height standard deviation scores both at admission and at the last examination, as well as lower weight standard deviation scores at the last examination, compared to those with OBSL1 variants (p < 0.05). Conclusion: To date, genotype–phenotype correlations have been identified in a limited number of studies. Further research involving larger cohorts is necessary to solidify these correlations. What is Known: • 3M syndrome is a well-known skeletal dysplasia caused by biallelic pathogenic variants in CUL7, OBSL1, and CCDC8 genes. • Despite genetic heterogeneity, clinical, and radiologic features show homogeneity in affected individuals. What is New: • Genotype-phenotype correlations have been established in limited studies. • The CUL7 group exhibited significantly lower height SDS at both admission and the final evaluation and lower weight SDS at the final examination compared to the OBSL1 group. • The frequency of variants in the OBSL1 gene among Turkish patients exceeds the rates reported in the literature. • Gradenigo syndrome is being reported for the first time in a patient with 3M syndrome. [ABSTRACT FROM AUTHOR]

Von Hippel-Lindau (VHL) syndrome is a multi-organ neoplastic disease characterized by highly vascular and cystic tumors in the central nervous system (CNS), retina, and visceral lesions, which are mainly caused by germline mutations in VHL. We aimed to detect novel mutations in VHL gene in families with VHL. Here, a large consanguineous four-generation family with variant phenotypes of VHL syndrome was recruited, and its molecular genetics were tested via Sanger sequencing. And various tools and databases were used to predict the variant pathogenicity, frequency, and protein function. Genetic investigation detected a c.351G > A nonsense mutation in VHL that altered the downstream reading frame and created a premature TGA stop signal, resulting in severely truncated pVHL (p.Trp117Ter). This mutation is absent from most public databases, and functional prediction bioinformatic tools demonstrated that this residue is conserved and that this variant is highly likely to be deleterious. The c.315G > A nonsense mutation in VHL is the causal mutation of this kindred that may lead to clear familial aggregation of VHL syndrome because of the dysfunction of the truncated pVHL. [ABSTRACT FROM AUTHOR]

ABSTRACT Kleefstra syndrome (KLEFS) is a genetic neurodevelopmental disorder caused by haploinsufficiency of EHMT1. The full spectrum of clinical features and genotype–phenotype correlations is currently not fully understood. We performed a retrospective chart review of patients with KLEFS evaluated at the Boston Children's Hospital Kleefstra Clinic. There were 65 individuals (40 females, 25 males, mean age 9.3 years). 17% had large 9q34 deletions (≥ 1 Mb), 29% had small 9q34 deletions (< 1 Mb), and 54% had sequence variants. Global developmental delay (GDD) or intellectual disability (ID) was present in 77%. Behavioral disorders, such as autism spectrum disorder (38%), were common. Epilepsy affected 15%. Systemic health issues included structural cardiac defects (40%), hearing loss (32%), and constipation (31%). Novel features including subgroups with significant motor impairment (24%) and refractory epilepsy (9%), as well as small numbers with opsoclonus‐like eye movements (n = 2), thrombocytopenia (n = 2), progressive cerebral atrophy (n = 1), and adrenal carcinoma (n = 1). 9q34 deletion subgroups had higher rates of GDD/ID (p = 0.037), significant motor impairment (p = 0.01), epilepsy (p = 0.004), and cortical visual impairment (p = 0.003) compared to the subgroup with sequence variants. This information may be used to improve clinical care as well as inform research and future therapeutic initiatives. [ABSTRACT FROM AUTHOR]

Phelan‐McDermid syndrome (PMS) is a rare genetic neurodevelopmental disorder that results from the loss of one functional copy of the SHANK3 gene. While many clinical features of PMS are well‐understood, there is currently limited literature on cardiovascular abnormalities in PMS. This report aims to evaluate the prevalence of aortic root dilation (ARD) among individuals with PMS and to understand if underlying genetic variation relates to risk for ARD. We present findings from 59 participants collected from a multisite observational study evaluating the phenotype and natural history of PMS. Individual echocardiographic and genetic reports were analyzed for aortic root measurements and genetic variant data, respectively. Our a priori hypothesis was that participants with chromosome 22 deletions with hg19 start coordinates on or before 49,900,000 (larger deletions) would have more instances of ARD than participants with deletion start coordinates after 49,900,000 (smaller deletions). Eight participants (14%) had ARD, and its presence was statistically significantly associated with large deletions (p = 0.047). Relatedly, participants with ARD had significantly more genes deleted on chromosome 22 than participants without ARD (p = 0.013). These results could aid in the identification of individuals with PMS who are at higher risk for ARD. [ABSTRACT FROM AUTHOR]

Alterations in the X‐linked recessive DMD gene cause dystrophinopathies with a broad clinical spectrum most commonly ranging from Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD) to cardiomyopathy or intellectual disability. Carrier females are commonly unaffected but may show signs of dystrophinopathies. In addition, few asymptomatic male carriers with elevated creatine kinase levels have been described possibly related to deletions around exon 48. We now further support this assumed genotype–phenotype correlation by reporting an attenuated phenotype in a three‐generation family with a deletion of exon 48 of the DMD gene with clinically unaffected carrier males and females. We confirmed deep intronic breakpoints in this family by genome sequencing, but such data are not available for published cases. Therefore, further observations are needed to clarify genotype–phenotype correlation in this region, since few reports also describe predicted in‐frame copy number changes affecting this region in association with classical signs of dystrophinopathies. [ABSTRACT FROM AUTHOR]

Introduction: Infantile hypotonia with psychomotor retardation and characteristic facies-1 (IHPRF1, MIM#615419) is a rare, birth onset, autosomal recessive disorder caused by homozygous or compound heterozygous truncating variants in NALCN gene (MIM#611549) resulting in a loss-of-function effect. Methods: We enrolled a new IHPRF1 patients' cohort in the framework of an international multicentric collaboration study. Using specialized in silico pathogenicity predictors and ad hoc structural analyses, we assessed the mechanistic consequences of the deleterious variants retrieved on NALCN structure and function. Results: To date 38 different NALCN variants have been retrieved from 33 different families, 26 from unrelated and 22 from related patients. We report on five new IHPRF1 patients from four different families, harboring four newly identified and one previously retrieved variant that exhibited a markedly significant functional impact, thereby compromising the functionality of the protein complex. Discussion: By widening the functional spectrum of biallelic variants affecting the NALCN gene, this article broadens the IHPRF1 syndrome's genotype-phenotype correlation and gives new insight into its pathogenic mechanism, diagnosis, and clinical management. [ABSTRACT FROM AUTHOR]

Background: Nuclear receptor subfamily 5 group A member 1 (NR5A1) plays pivotal roles in steroidogenesis and gonadal development. 46, XY disorder of sexual development (DSD) caused by NR5A1 mutations is a rare genetic condition. This study aimed to provide a comprehensive analysis of the clinical characteristics and molecular defects observed in 19 Chinese patients with NR5A1 variants, including assessing the deleterious effects of novel variants in vitro and evaluating their functional impact on the gonad and adrenal glands in vivo. Materials and methods: Subjects with NR5A1 variants were identified from 223 Chinese 46, XY DSD patients via next-generation sequencing. In-silico analysis and functional assays were performed to evaluate the transcriptional activity, expression levels and nuclear localization of novel NR5A1 variants. The histological structure of the gonads was evaluated via immunohistochemistry (IHC). Results: Patients with NR5A1 gene variants presented with serious conditions, including micropenis, cryptorchidism, azoospermia, and radiological abnormalities of the spleen. Five novel NR5A1 variants were identified, including heterozygous p.Y5*, p.Q42E and p.L359_L363del, as well as copy number variation (CNV) of chr9:127213317–127570245_del and an exon 6 duplication. A total of 63.2% (12/19) of patients harbored additional variants other than NR5A1. Defective transcriptional regulatory activities and abnormal protein expression levels were observed in NR5A1 variants. The reduced levels of DHEA-S and 11-oxygenated steroids indicate a mild impairment in adrenal function among certain patients. The IHC analysis of the testis revealed intact expression levels of SOX9 in Sertoli cells, while significant differences were observed in the expression pattern of CYP17A1 in Leydig cells among patients. The preserved maturation of adult Leydig cells in the patients may trigger spontaneous puberty. Conclusions: Patients with NR5A1 mutations exhibit complex phenotypes. The observed clinical heterogeneity may be attributed to oligogenic mutations, dysregulated Leydig cell function, as well as the impaired ability to modulate the transcription of target genes. [ABSTRACT FROM AUTHOR]

Background: Interstitial chromosome 11 long arm deletions (11q13-q23) represent a rare cytogenetic abnormality characterized by non-specific clinical features including intellectual disability and several malformations without a clear genotype-phenotype correlation. We describe the first case of interstitial 11q deletion identified in a boy with Sprengel's deformity and provide a review of the literature. Case presentation: We report a 9-year-old boy with congenital scapular deformity, iris and chorioretinal coloboma, normal intelligence, and a history of mild motor development delay. The karyotype showed a de novo large 11q deletion. Fluorescence in situ hybridization (FISH) confirmed that the deletion is interstitial, and array comparative genomic hybridization (aCGH) revealed a loss of 25.8 Mb encompassing the 11q14.1-q22.3 region. Conclusions: The present case and the literature review of 61 previously published cases highlight the clinical heterogeneity and the lack of genotype-phenotype correlation in interstitial 11q deletions. Sprengel's deformity found in our patient might be a new finding in 11q deletions or, more probably, a fortuitous association. [ABSTRACT FROM AUTHOR]

Spinocerebellar ataxias (SCAs) are a diverse group of hereditary neurodegenerative disorders characterized by progressive degeneration of the cerebellum and other parts of the nervous system. In this study, we examined the genotype‒phenotype correlations in SCAs within the Brazilian population by leveraging a comprehensive dataset of 763 individuals from SARAH Network of Rehabilitation Hospitals. Using a retrospective, cross-sectional, observational, multicentric approach, we analysed medical records and conducted standardized molecular testing to explore epidemiological characteristics, clinical manifestations, and genetic profiles of SCAs in Brazil. Our findings revealed the predominance of SCA3, followed by SCA7 and SCA2, which aligns with global trends and reflects the specific genetic landscape of Brazil. A significant inverse relationship between the age of symptom onset and CAG repeat length in the mutated allele was observed across SCAs 2, 3, and 7. This study also highlights a trend towards paternal inheritance in SCA2 and details the distribution of CAG repeat expansions, which correlates larger expansions with earlier onset and specific symptomatology. This extensive analysis underscores the critical importance of genetic testing in the diagnosis and management of SCAs and enlightens the intricate genotype‒phenotype interplay within a genetically diverse population. Despite certain limitations, such as potential selection bias and the retrospective nature of the study, our research provides invaluable insights into the prevalence, genetic underpinnings, and clinical variability of SCAs in Brazil. We suggest a broader demographic scope and investigations into nonmotor symptoms in future studies to obtain a more comprehensive understanding of SCAs. [ABSTRACT FROM AUTHOR]

Biallelic WARS2 pathogenic variants responsible for partial defect in aminoacylation, have recently been reported in subjects presenting with late-onset phenotypes combining dopa-responsive early-onset dystonia parkinsonism with altered DaTSCAN and progressive myoclonus ataxia. Here, we present the case of a 39-year-old male with childhood-onset progressive dopa-responsive dystonia parkinsonism, prominent psychiatric features and ataxia whose genome sequencing identified a p.(Arg36Ter) nonsense variant and a hypomorphic p.(Trp13Gly) missense variant, allowing the diagnosis of WARS2-related disease. The p.(Trp13Gly) missense variant has previously been reported in individuals with less severe phenotypes than those carrying biallelic WARS2 loss-of-function variants. Among these individuals, two subjects had similar genetic backgrounds and almost identical clinical history to our patient. Our report brings additional proof that the p.(Trp13Gly) variant acts as a hypomorphic allele, offering insight on a genotype-phenotype correlation in WARS2-related disorders. [ABSTRACT FROM AUTHOR]

Background and Aims: Since 2016, biallelic mutations in the membrane metalloendopeptidase (MME) gene have been associated with late‐onset recessive CMT2 (CMT2T). More recently, heterozygous mutations have also been identified in familial and sporadic patients with late‐onset axonal neuropathy, ranging from subclinical to severe. This indicates that the heterozygous MME variants may not be fully penetrant, or alternatively, that they may be a potential risk factor for neuropathy. Here, we describe the clinical, neurophysiological, and genetic findings of 32 CM2T Italian patients. Methods: The patients were recruited from four different Italian referral centers. Following a comprehensive battery of neurological, electrophysiological, and laboratory examinations, the patients' DNA was subjected to sequencing in order to identify any variants in the gene. Bioinformatic and modeling analyses were performed to evaluate the identified variants' effects. Results: We observe a relatively mild axonal sensory‐motor neuropathy with a greater impairment of the lower extremities. Biallelic and monoallelic patients exhibit comparable disease severity, with an earlier onset observed in those with biallelic variants. When considering a subgroup with more than 10 years of disease, it becomes evident that biallelic patients exhibit a more severe form of neuropathy. This suggests that they are more prone to quick progression. Interpretation: CM2T has been definitively defined as a late‐onset neuropathy, with a typical onset in the fifth to sixth decades of life and a more rapidly progressing worsening for biallelic patients. CMT2T can be included in the neuropathies of the elderly, particularly if MME variants heterozygous patients are included. [ABSTRACT FROM AUTHOR]

Background: WFS1-spectrum disorders are caused by a mutation in the WFS1 gene. The term includes a wide range of rare disorders, from the most severe Wolfram syndrome with autosomal recessive inheritance to milder clinical manifestations with a single causative variant in the WFS1 gene, such as Wolfram-like syndrome, low-frequency sensorineural hearing loss (LFSNHL), isolated diabetes mellitus (DM), nonsyndromic optic atrophy (OA), and isolated congenital cataracts. Methods: The aim of this study was to evaluate genotype–phenotype correlations in Polish patients with WFS1-spectrum disorders. The study group constituted 22 patients (10 F; 12 M), including 10 patients (3 F; 7 M) referred to the Outpatient Clinic for Rare Diseases in Children and Adolescents and Diabetogenetics between 2019 and 2024 with clinical symptoms suggestive of WFS1-spectrum disorders, and 12 of their first-degree relatives (7 F; 5 M) from 10 families in Poland. Molecular testing was performed using tNGS (Targeted Next Generation Sequencing; Illumina) and analyzed for variants in the WFS1 gene. Results: Thirteen different variants in the WFS1 gene were found in 22 individuals (10 patients and family members), including the identification of two new variants (c.1535T>C and c.2485C>G). All patients had hyperglycemia or DM, hearing impairment, OA, or a combination of these symptoms. Four patients in the study group were diagnosed with Wolfram syndrome and all were compound heterozygotes for variants in the WFS1 gene. Conclusions: The evaluation of molecular characteristics in combination with clinical symptoms broadens the understanding of WFS1-spectrum disorders and allows more accurate management and prognosis for patients with this diagnosis. [ABSTRACT FROM AUTHOR]

The CYP2C19 enzyme is implicated in the metabolism of several clinically used drugs. Its phenotype is usually predicted by genotyping and indicates the expected enzymatic activity for each patient. However, with a few exceptions, CYP2C19 genotyping has not resulted in a reliable prediction of the metabolizer status, since most of the evidence currently available for this prediction comes from research into populations of predominantly European ancestry. Therefore, this review discusses the main factors that may alter the expected phenotype, as well as the urgent need to include ethnically diverse populations in further studies, so that, in the long term, it is possible to establish guidelines appropriate to these groups. [ABSTRACT FROM AUTHOR]

Stargardt disease type 1 (STGD1) is caused by biallelic pathogenic variants in ABCA4. These variants vary in their effect on the resulting protein and the disease phenotype. Not all variant combinations cause disease, which complicates the determination of the recurrence risk of STGD1. Previously, the recurrence risk of STGD1 was estimated by analyzing variants in patient data and using their population variant frequencies in which white patients are overrepresented. Furthermore, assuming that variant effects are independent of genetic ancestry, estimates were made for each gnomAD population. In this article, the effects of missing heritability, de novo variants, reduced penetrance of variants and sex/gender are incorporated and discussed. [ABSTRACT FROM AUTHOR]

Abstract Alexander disease (ALXDRD) is a rare neurodegenerative disorder of astrocytes resulting from pathogenic variants in the GFAP gene. The genotype-phenotype correlation remains elusive due to the variable expressivity of clinical manifestations. In an attempt to clarify the effects of GFAP variants in ALXDRD, numerous studies were collected and analyzed. In particular, we systematically searched for GFAP variants associated with ALXDRD and collected information on the location within the gene and protein, prediction of deleteriousness/pathogenicity, occurrence, sex and country of origin of patients, DNA source, genetic testing, and clinical signs. To identify possible associations, statistical analyses and meta-analyses were applied, thus revealing a higher than expected percentage of adult patients with ALXDRD. Furthermore, substitution of Arginine, the most frequently altered residue among the 550 predominantly missense causative GFAP variants collected, were mostly de novo and more prevalent in early-onset forms of ALXDRD. The effect of defective splicing in modifying the impact of GFAP variants on the age of onset of ALXDRD was also postulated after evaluating the distribution of the corresponding deleterious predictive values. In conclusion, not only previously unrecognized genotype-phenotype correlations were revealed in ALXDRD, but also subtle mechanisms could explain the variable manifestations of the ALXDRD clinical phenotype.

Abstract The LONP1 gene encodes Lon protease, which is responsible for degrading damaged or misfolded proteins and binding mitochondrial DNA. Previously, LONP1 variants have been identified in patients with cerebral, ocular, dental, auricular, and skeletal anomalies (CODAS syndrome) and mitochondrial diseases. Seizures were occasionally observed. However, the association between LONP1 and epilepsy remains elusive. In this study, we performed trio-based whole-exome sequencing in a cohort of 450 patients with unexplained epilepsy and identified four pairs of compound heterozygous LONP1 variants in four unrelated cases. All patients exhibited good responses to anti-seizure medications and demonstrated no developmental delay or intellectual disabilities. The variant allele frequencies observed in this study were absent or low in the general population and were significantly lower than those of benign variants. At least one variant in each biallelic pair affected hydrogen bonding and/or altered protein stability. The CODAS syndrome-associated variants were concentrated in the AAA+ module, especially the α domain. Four of the five mitochondrial disease-associated variants were located in the AAA + domain and the NTD5H and NTD3H subdomains. In contrast, each of the biallelic variants from the patients with pure epilepsy had one variant located in the linker domain, and the other variant located in the mitochondrial targeting sequence or P domain. This study suggested that LONP1 gene is potentially a novel candidate gene for pure epilepsy. The phenotypic variation is associated with the sub-regional effects of variants.

Background Objective Methods Results Conclusion The pentanucleotide (TTTCA) repeat expansion (exp) insertion, along with the accompanying (TTTTA)exp, causes familial cortical myoclonic tremor with epilepsy (FCMTE). The genotype–phenotype correlations and intergenerational instabilities related to (TTTCA)exp and (TTTTA)exp are still unclear.The aim was to investigate the genotype–phenotype correlations and intergenerational instabilities related to (TTTCA)exp and (TTTTA)exp in FCMTE1.We performed targeted long‐read sequencing on 77 FCMTE1 patients. After quality control, metrics such as total repeat count, respective (TTTTA)exp and (TTTCA)exp count, and interruptions were assessed in 73 patients. Correlations between metrics and the patients' clinical features, as well as repeat instability during parental transmission, were analyzed.Among 73 alleles, the average total repeat counts were 848 ± 152 units, with (TTTTA)exp and (TTTCA)exp averaging 498 ± 196 units and 356 ± 110 units, respectively. (TTTCA)exp counts were inversely correlated with the age at onset for cortical tremor (Spearman's rho = −0.348, P = 0.005) and epilepsy (Spearman's rho = −0.424, P = 0.003). A negative correlation was found between (TTTCA)exp counts and relatively moderate seizure pattern with prodrome (odds ratio = 0.988, 95% confidence interval: 0.980–0.995, P = 0.002). During parental transmission, (TTTCA)exp counts increased significantly (P = 0.007), with maternal transmission showing a significantly larger increase compared to paternal transmission (P = 0.013).The (TTTCA)exp insertion serves as the length‐dependent pathogenic component within the two‐motif repeat expansion. Its differential expanding nature during parental transmissions is highly associated with the genetic anticipation in FCMTE1. © 2024 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Introduction: Congenital adrenal hyperplasia (CAH) is characterized by a broad spectrum of symptoms. This study aimed to describe genotype-phenotype correlations, clinical manifestations at diagnosis, and the frequency of feminizing surgery in childhood. Methods: A nationwide retrospective cohort study of patients diagnosed with CAH, at the age of ≤18 years, between 1943 and 2018. CAH was identified in national registries and validated through medical record reviews and phenotypically classified as salt-wasting (SW), simple virilizing (SV), or non-classic (NC) CAH. In a sub-cohort (diagnosed between 1999 and 2018), clinical data and feminizing surgery data were investigated. CYP21A2 variants were grouped as Null, A, B, C, and D. Results: The cohort comprised 379 patients with CAH. Genotype-phenotype correlations were as follows: Null and SW (100%), A and SW (94%), B and SV (51%), and C and NC (75%). In the sub-cohort (n = 159, females = 99), the female-to-male ratios were SW = 1.5, SV = 1.1, and NC = 2.3. Symptoms of precocious pseudopuberty dominated at diagnosis (39%). Males presented with significantly advanced bone age by the time of diagnosis (p = 0.0009). In 53% of females (n = 53), virilization of the external genitalia was present at the time of diagnosis, and in 46% (n = 46), this already developed prenatally. Of the prenatal virilized females, 85% underwent early feminizing genitoplasty. Virilization was identified in both mild and severe genotypes. Conclusion: Milder genotypes do not accurately predict CAH phenotype or prenatally reject serious outcomes such as virilization. The frequency of early genitoplasty is high among females with prenatal virilization. The delayed diagnosis and non-diagnosis of especially males with mild CAH advocate for a more prominent role of genetic testing in the diagnostic and screening for CAH. [ABSTRACT FROM AUTHOR]

15q24.1 microdeletion syndrome is a recently described condition often resulting from non‐allelic homologous recombination (NAHR). Typical clinical features include pre and post‐natal growth retardation, facial dysmorphism, developmental delay and intellectual disability. Nonspecific urogenital, skeletal, and digit abnormalities may be present, although other congenital malformations are less frequent. Consequently, only one case was reported prenatally, complicating the genotype–phenotype correlation and the genetic counseling. We identified prenatally a second case, presenting with cerebral abnormalities including hydrocephaly, macrocephaly, cerebellum hypoplasia, vermis hypoplasia, rhombencephalosynapsis, right kidney agenesis with left kidney duplication and micropenis. Genome‐wide aCGH assay allowed a diagnosis at 26 weeks of amenorrhea revealing a 1.6 Mb interstitial deletion on the long arm of chromosome 15 at 15q24.1‐q24.2 (arr[GRCh37] 15q24.1q24.2(74,399,112_76,019,966)x1). A deep review of the literature was undertaken to further delineate the prenatal clinical features and the candidate genes involved in the phenotype. Cerebral malformations are typically nonspecific, but microcephaly appears to be the most frequent in postnatal cases. Our case is the first reported with a frank cerebellar involvement. [ABSTRACT FROM AUTHOR]

Objective: Congenital, non-syndromic orofacial clefts (CL/P) are infrequently monogenic in etiology. However, heterozygous pathogenic CDH1 germline variants were reported in a few non-syndromic CL/P families, as well as in one syndromic form of CL/P: the blepharocheilodontic syndrome. CDH1 encodes epithelial cadherin (E-cadherin), and close to 300 different pathogenic CDH1 variants are listed in the ClinVar mutation database. The majority of CDH1 germline variants are implicated in hereditary diffuse gastric cancer (HDGC) susceptibility. The purpose of this study was to classify the CDH1 c.760G>A (p.Asp254Asn) mutation with respect to its resulting phenotype. Methods: Exome sequencing and targeted Sanger sequencing were performed in a family segregating CL/P. A review of pathogenic CDH1 variants in ClinVar and those identified in a PubMed/MEDLINE search was performed. Results: We identified a family with six individuals, who were 35–77 years old (mean 56 years) at their last examination, uniformly affected with bilateral CL/P. The CDH1 c.760G>A variant segregated with CL/P. This variant had been reported in 21 individuals, most often children and young adults, from six families. We determined a significant sex preponderance for this variant regarding CL/P: all 16 male and 5 of 11 female heterozygotes presented with CL/P. Furthermore, none of the heterozygous individuals in seven families reported any gastrointestinal tumors. Conclusions: The recurrent CDH1 c.760G>A mutation confers a high risk for CL/P, with strong male preponderance. This review of 27 mutation carriers, including 3 who were 68, 70, and 77 years of age, indicates that c.760G>A does not confer an increased risk for HDGC. The relevance of differentiating craniofacial from cancer phenotypes in mutation carriers is substantial for precision medicine and for counseling families. [ABSTRACT FROM AUTHOR]

Rare diseases are heterogeneous diseases characterized by various symptoms and signs. Due to the low prevalence of such conditions (less than 1 in 2000 people), medical expertise is limited, knowledge is poor and patients' care provided by medical centers is inadequate. An accurate diagnosis is frequently challenging and ongoing research is also insufficient, thus complicating the understanding of the natural progression of the rarest disorders. This review aims at presenting the multimodal approach supported by the integration of multiple analyses and disciplines as a valuable solution to clarify complex genotype–phenotype correlations and promote an in-depth examination of rare disorders. Taking into account the literature from large-scale population studies and ongoing technological advancement, this review described some examples to show how a multi-skilled team can improve the complex diagnosis of rare diseases. In this regard, Facio-Scapulo-Humeral muscular Dystrophy (FSHD) represents a valuable example where a multimodal approach is essential for a more accurate and precise diagnosis, as well as for enhancing the management of patients and their families. Given their heterogeneity and complexity, rare diseases call for a distinctive multidisciplinary approach to enable diagnosis and clinical follow-up. [ABSTRACT FROM AUTHOR]

Alexander disease (ALXDRD) is a rare neurodegenerative disorder of astrocytes resulting from pathogenic variants in the GFAP gene. The genotype-phenotype correlation remains elusive due to the variable expressivity of clinical manifestations. In an attempt to clarify the effects of GFAP variants in ALXDRD, numerous studies were collected and analyzed. In particular, we systematically searched for GFAP variants associated with ALXDRD and collected information on the location within the gene and protein, prediction of deleteriousness/pathogenicity, occurrence, sex and country of origin of patients, DNA source, genetic testing, and clinical signs. To identify possible associations, statistical analyses and meta-analyses were applied, thus revealing a higher than expected percentage of adult patients with ALXDRD. Furthermore, substitution of Arginine, the most frequently altered residue among the 550 predominantly missense causative GFAP variants collected, were mostly de novo and more prevalent in early-onset forms of ALXDRD. The effect of defective splicing in modifying the impact of GFAP variants on the age of onset of ALXDRD was also postulated after evaluating the distribution of the corresponding deleterious predictive values. In conclusion, not only previously unrecognized genotype-phenotype correlations were revealed in ALXDRD, but also subtle mechanisms could explain the variable manifestations of the ALXDRD clinical phenotype. [ABSTRACT FROM AUTHOR]

The current genetic diagnostic workup of congenital cataract (CC) is mainly based on NGS panels, whereas exome sequencing (ES) has occasionally been employed. In this multicentre study, we investigated by ES the detection yield, mutational spectrum and genotype–phenotype correlations in a CC cohort recruited between 2020 and mid‐2022. The cohort consisted of 67 affected individuals from 51 unrelated families and included both non‐syndromic (75%) and syndromic (25%) phenotypes, with extra‐CC ocular/visual features present in both groups (48% and 76%, respectively). The functional effect of variants was predicted by 3D modelling and hydropathy properties changes. Variant clustering was used for the in‐depth assessment of genotype–phenotype correlations. A diagnostic (pathogenic or likely pathogenic) variant was identified in 19 out of 51 probands/families (~37%). In a further 14 probands/families a candidate variant was identified: in 12 families a VUS was detected, of which 9 were considered plausibly pathogenic (i.e., 4 or 5 points according to ACMG criteria), while in 2 probands ES identified a single variant in an autosomal recessive gene associated with CC. Eighteen probands/families, manifesting primarily non‐syndromic CC (15/18, 83%), remained unsolved. The identified variants (8 P, 12 LP, 10 VUS‐PP, and 5 VUS), half of which were unreported in the literature, affected five functional categories of genes involved in transcription/splicing, lens formation/homeostasis (i.e., crystallin genes), membrane signalling, cell–cell interaction, and immune response. A phenotype‐specific variant clustering was observed in four genes (KIF1A, MAF, PAX6, SPTAN1), whereas variable expressivity and potential phenotypic expansion in two (BCOR, NHS) and five genes (CWC27, KIF1A, IFIH1, PAX6, SPTAN1), respectively. Finally, ES allowed to detect variants in six genes not commonly included in commercial CC panels. These findings broaden the genotype–phenotype correlations in one of the largest CC cohorts tested by ES, providing novel insights into the underlying pathogenetic mechanisms and emphasising the power of ES as first‐tier test. [ABSTRACT FROM AUTHOR]

Missense mutations in cardiac myosin binding protein C (cMyBP-C) are known to cause hypertrophic cardiomyopathy (HCM). The W792R mutation in the C6 domain of cMyBP-C causes severe, early onset HCM in humans, yet its impact on the function of cMyBP-C and the mechanism through which it causes disease remain unknown. To fully characterize the effect of the W792R mutation on cardiac morphology and function in vivo, we generated a murine knock-in model. We crossed heterozygous W792RWR mice to produce homozygous mutant W792RRR, heterozygous W792RWR , and control W792RWW mice. W792RRR mice present with cardiac hypertrophy, myofibrillar disarray and fibrosis by postnatal day 10 (PND10), and do not survive past PND21. Full-length cMyBP-C is present at similar levels in W792RWW, W792RWR and W792RRR mice and is properly incorporated into the sarcomere. Heterozygous W792RWR mice displayed normal heart morphology and contractility. Permeabilized myocardium from PND10 W792RRR mice showed increased Ca2+ sensitivity, accelerated cross-bridge cycling kinetics, decreased cooperativity in the activation of force, and increased expression of hypertrophy-related genes. In silico modeling suggests that the W792R mutation destabilizes the fold of the C6 domain and increases torsion in the C5-C7 region, possibly impacting regulatory interactions of cMyBP-C with myosin and actin. Based on the data presented here, we propose a model in which mutant W792R cMyBP-C preferentially forms Ca2+ sensitizing interactions with actin, rather than inhibitory interactions with myosin. The W792R-cMyBP-C mouse model provides mechanistic insights into the pathology of this mutation and may provide a mechanism by which other central domain missense mutations in cMyBP-C may alter contractility, leading to HCM. [Display omitted] • Mutations in cardiac myosin binding protein C (cMyBP-C) are a leading cause of hypertrophic cardiomyopathy. • The W792R mutation in the central C6 domain of cMyBP-C leads to severe disease in humans through unknown mechanisms. • Mutant W792R cMyBP-C is stably expressed and is appropriately localized within the sarcomere of W792R knock-in mice. • Homozygous W792R leads to a severe, early onset heart failure phenotype that is not compatible with life. • The W792R mutation is predicted to disrupt the orientation of C6 and its neighboring domains, altering cMyBP-C function. [ABSTRACT FROM AUTHOR]

Background: This case report explores the relationship between genetics and phenotypic variability in autosomal dominant vitreoretinochoroidopathy (ADVIRC). The study focuses on a case presenting a novel mutation in the BEST1 gene and its phenotype in the case's relatives, shedding light on the structural and functional intricacies underlying this rare ophthalmologic disorder. Case Presentation: A 33-year-old female presented for consultation with a history of bilateral retinal damage accompanied by a complaint of decreased visual acuity, progressive visual field deficit, and night blindness over the past year. Ophthalmic examination revealed a distinctive phenotype, including fibrillar vitreous, pigmented cells, and atrophic hyperpigmented retina in the periphery which was suggestive of a diagnosis of ADVIRC. Genetic testing revealed a heterozygous c.1101–1 G>T variant in BEST1, a novel splice site mutation. Functional analysis confirmed its impact on pre-mRNA splicing, resulting in an in-frame deletion (p(Ser367_Asn579del)). Family investigation revealed varying degrees of ophthalmologic impairment in the patient's mother and half-sister, both carrying the same mutation. Conclusions: This case report provides the first clinical description of the c.1101–1 G>T mutation in the BEST1 gene associated with ADVIRC. The presence of intrafamilial variability, as evidenced by the differing clinical features observed in the index case and her half-sister, suggests the potential involvement of mechanisms influencing phenotype expression. Abbreviation: ADVIRC : autosomal dominant vitreoretinochoroidopathy; RNA : ribonucleic acid; RPE : retinal pigment epithelium. [ABSTRACT FROM AUTHOR]

Biallelic variants of steroidogenic acute regulatory protein (STAR/STARD1) may cause primary adrenal insufficiency and 46,XY disorder of sex development. STAR plays a pivotal role in transporting cholesterol into mitochondria where cholesterol serves as an essential substrate for initiating steroid biosynthesis by its conversion to pregnenolone. Generally, loss-of-function mutations of STAR cause the classic form of lipoid congenital adrenal hyperplasia (LCAH) where steroidogenesis of the adrenal cortex and the gonads is severely affected. By contrast, partial activity of STAR causes a less severe phenotype, the non-classic LCAH, which is characterized by later onset and initial manifestation with isolated adrenal insufficiency only. Disease-causing STAR variants are very rare. Numerous variants of all types have been described worldwide. Prevailing variants have been reported from Japan and Korea and in some population clusters where STAR is more common. Genotype–phenotype correlation is pretty good for STAR variants. While the exact mechanisms of cholesterol transport into mitochondria for steroidogenesis are still under investigation, the important role of STAR in this process is evident by inactivating STAR variants causing LCAH. The mechanism of disease with STAR deficiency is best described by a two-hit model: the first hit relates to impaired cholesterol import into mitochondria and thus lack of substrate for all steroid hormone biosynthesis; the second hit then relates to massive cytoplasmic lipid overload (evidenced by typically enlarged and fatty adrenal glands) leading to cell death and organ destruction. This review summarizes phenotype and genotype characteristics of human STAR variants found through the ClinVar database. [ABSTRACT FROM AUTHOR]

Background: Congenital disorders of glycosylation (CDG) are a group of neurometabolic diseases that result from genetic defects in the glycosylation of proteins and/or lipids. Multiple pathogenic genes contribute to the varying reported phenotypes of individuals with CDG‐1 syndromes, most of which are inherited as autosomal recessive traits, although X‐linked inheritance has also been reported. Pathogenic variants in the asparagine‐linked glycosylation 13 homolog (ALG13) gene have been implicated in the aetiology of developmental and epileptic encephalopathy (DEE) 36 (OMIM:*300776, DEE36). The NM_001099922.3:c.320A>G; p.(Asn107Ser) variant is the most frequently described pathogenic variant in ALG13, with 59 females and 2 males with this variant reported to date. Methods: We report on a male with a de novo, hemizygous variant in ALG13: c.320A>G; p.(Asn107Ser), whose phenotype resembles that of two previously reported males with the same variant. Results: All three males have a de novo mutation, infantile spasms, DEE, drug‐resistant epilepsy, intellectual disability, dysmorphic findings, recurrent infections, skeletal anomalies, brain abnormalities and a movement disorder: a phenotype not consistently reported in males with other pathogenic variants in ALG13. Conclusion: The similarity of phenotype in the three males with the c.320A>G variant in ALG13, suggests a possible genotype–phenotype correlation. [ABSTRACT FROM AUTHOR]

Background. Biotin is a water-soluble vitamin that plays a key role in carboxylation. The formation of free biotin is impaired in biotinidase deficiency (BD), resulting in impaired biotin-dependent carboxylase functions. Based on the percentage of residual serum enzyme activity, BD is classified as partial and profound. Methods. Retrospective data including gender, age, parental consanguinity, family history, biotinidase activity analyses, type of deficiency (partial-profound), physical examination, treatment, and genotypes were evaluated in patients diagnosed with biotinidase deficiency in a single center in the eastern region of Türkiye. Patients whose biotinidase enzyme activity was below 30% with biallelic variants in the BTD gene were diagnosed as BD. Results. A total of 302 patients were included in the study. Parental consanguinity was present in 135 (44.7%) of them. Two hundred eighty-six (94.7%) were diagnosed by neonatal screening, 14 (4.6%) by family screening and two (0.06%) by clinical symptoms. Ninety-two (30.5%) of the patients were followed-up with profound deficiency and 210 (69.5%) with partial deficiency. A total of 306 variants were detected. Twenty different variants (3 novel - 3 rare) and 31 different genotypes were detected. The 3 most frequently detected variants were c.410G>A (p.Arg137His; 47.3%), c.1270G>C (p.Asp424His; 29.7%), and c.38_44delGCGGCTGinsTCC (p.Cys13Phefs*36; 15.3%). The 3 most frequently identified genotypes were c.410G>A (p.Arg137His) / c.1270G>C (p.Asp424His) compound heterozygous (32.4%), c.410G>A (p.Arg137His) homozygous (24.8%), and c.38_44delGCGGCTGinsTCC (p.Cys13Phefs*36) / c.1270G>C (p.Asp424His) compound heterozygous (12.2%). Patients with c.410G>A (p.Arg137His) homozygous variant, c.38_44delGCGGCTGinsTCC (p.Cys13Phefs*36) homozygous variant and c.38_44delGCGGCTGinsTCC (p.Cys13Phefs*36) / c.410G>A (p.Arg137His) compound heterozygous variant were statistically significantly associated with profound deficiency. Compound heterozygosity of c.410G>A (p.Arg137His) / c.1270G>C (p.Asp424His) variants were significantly associated with partial deficiency. Conclusions. The association between the BTD genotype and biochemical phenotype is not always consistent. Our study provides valuable data by adding variants with genotype-phenotype correlations to the literature and three novel variants, which can provide significant guidance in clinical follow-up. [ABSTRACT FROM AUTHOR]

The autosomal dominant Okur–Chung neurodevelopmental syndrome (OCNDS: OMIM #617062) is a rare neurodevelopmental disorder first described in 2016. Features include developmental delay (DD), intellectual disability (ID), behavioral problems, hypotonia, language deficits, congenital heart abnormalities, and non‐specific dysmorphic facial features. OCNDS is caused by heterozygous pathogenic variants in CSNK2A1 (OMIM *115440; NM_177559.3). To date, 160 patients have been diagnosed worldwide. The number will likely increase due to the growing use of exome sequencing (ES) and genome sequencing (GS). Here, we describe a novel OCNDS patient carrying a CSNK2A1 variant (NM_177559.3:c.140G>A; NP_808227.1:p.Arg47Gln). Phenotypically, he presented with DD, ID, generalized hypotonia, speech delay, short stature, microcephaly, and dysmorphic features such as low‐set ears, hypertelorism, thin upper lip, and a round face. The patient showed several signs not yet described that may extend the phenotypic spectrum of OCNDS. These include prenatal bilateral clubfeet, exotropia, and peg lateral incisors. However, unlike the majority of descriptions, he did not present sleep disturbance, seizures or gait difficulties. A literature review shows phenotypic heterogeneity for OCNDS, whether these patients have the same variant or not. This case report is an opportunity to refine the phenotype of this syndrome and raise the question of the genotype–phenotype correlation. [ABSTRACT FROM AUTHOR]

The phenotypes associated with MED12 pathogenic variants are diverse. Male patients usually have missense variants, but the effects of base substitutions on mRNA splicing have not been investigated. Here, we report a Japanese brother with intellectual disability, characteristic facial appearance with blepharophimosis, cleft palate, Fallot tetralogy, vesicoureteral reflux, and deafness. A known missense pathogenic variant was detected in MED12, NM_005120.3:c.887G>A p.(Arg296Gln), and X‐linked Ohdo syndrome was diagnosed in combination with their phenotype. mRNA splicing of MED12 was evaluated qualitatively and quantitatively using long‐range PCR‐based targeted RNA sequencing (reverse transcribed long amplicon sequencing), and it was shown that this missense variant simultaneously causes aberrant splicing of the 42‐bp in‐frame deletion in exon 7, r.847_888del, which accounts for approximately 30% of the mRNAs in both siblings. The X chromosome inactivation study showed that the X chromosome carrying the mutant allele was 100% inactivated in the carrier mothers. mRNA level analysis is essential for the accurate interpretation of the effects of variants. In this case, the MED12 protein function may be reduced by more than just an amino acid substitution, resulting in the patients with the most severe phenotype of MED12‐related syndrome in males. [ABSTRACT FROM AUTHOR]

ObjectiveNetherton syndrome (NS) is a rare hereditary dermatosis, and the correlation between genotype and phenotype in this disease warrants further investigation. This study aimed to explore the genotype-phenotype correlation in NS.MethodsWe collect cases from our clinic and relevant literature. After rigorous screening, we included 162 patients with NS-associated symptoms and SPINK5 mutations. We characterized the distribution and mutation types of allele variants. Logistic regression was employed to analyze the correlation between the location of these variants and phenotypes. Additionally, the association between the homozygous condition of variants and death during infancy was analyzed using the Chi-square test.ResultsAmong 162 patients, we identified 324 allele variants, comprising 75 different mutations. Of these, 73 patients carried heterozygous variants, while 89 patients had homozygous variants. We observed that patients with variants or homozygous variants located in the 5′ half of the gene were more likely to experience failure to thrive (P < 0.05). Similarly, variants or homozygous variants located outside DomainR-5 were also associated with an increased risk of failure to thrive (P < 0.05). Furthermore, variants in domain regions were significantly correlated with the presence of ichthyosis linearis circumflexa (P < 0.01). Patients with homozygous fatal variants (c.153delT, c.1431-12G>A, c.1111C>T, c. 1887 + 1G>A, and c. 995delT) had a higher likelihood of mortality during infancy (P < 0.001).ConclusionOur study provides valuable insights into the genotype-phenotype correlation in Netherton syndrome, enhancing our understanding of the disease and potentially informing the development of future therapeutic approaches.

Familial Mediterranean Fever (FMF) is a hereditary autoinflammatory disorder, particularly present in the Mediterranean populations, and associated with pathogenic variants in the MEFV gene. This study aims to investigate the distribution of MEFV variants in a large cohort of Lebanese patients, and to explore the genotype-phenotype correlation among affected individuals. A retrospective analysis was conducted on 3,167 patients referred for MEFV sequencing at the Medical Genetics and Genomics Center(CGGM) at Saint-Joseph University of Beirut-Lebanon, from 2006 to 2023. Sanger sequencing was used to detect MEFV variants, focusing initially on hot-spot exons. Among the 3,167 patients, 46.73% (N = 1,480) carried at least one MEFV variant. The most common variants detected were M694V and V726A, both found in 28.98% of cases, followed by E148Q(27.83%) and M694I(13.98%). Moreover, Shiites and Sunni Muslims, and individuals from South and North Lebanon exhibited the highest frequency of variants. Interestingly, family history was found to be significantly higher in patients having two MEFV variants than those with one variant (p = 0.0026). The most commonly reported symptoms were fever(78%), abdominal pain(88%), joint pain(65%), and thoracic pain(46%). The genotype-phenotype correlation analysis revealed a more severe phenotype in patients carrying the M694V or V726A mutations compared to those with the homozygous E148Q genotype. This study, the largest in Lebanon, highlights the high prevalence of MEFV variants, particularly M694V and V726A, in FMF patients. Our data provide valuable insights into the genetic landscape of FMF in Lebanon and emphasize the importance of early genetic screening for a better disease management and genetic counselling.

IntroductionInfantile hypotonia with psychomotor retardation and characteristic facies-1 (IHPRF1, MIM#615419) is a rare, birth onset, autosomal recessive disorder caused by homozygous or compound heterozygous truncating variants in NALCN gene (MIM#611549) resulting in a loss-of-function effect.MethodsWe enrolled a new IHPRF1 patients’ cohort in the framework of an international multicentric collaboration study. Using specialized in silico pathogenicity predictors and ad hoc structural analyses, we assessed the mechanistic consequences of the deleterious variants retrieved on NALCN structure and function.ResultsTo date 38 different NALCN variants have been retrieved from 33 different families, 26 from unrelated and 22 from related patients. We report on five new IHPRF1 patients from four different families, harboring four newly identified and one previously retrieved variant that exhibited a markedly significant functional impact, thereby compromising the functionality of the protein complex.DiscussionBy widening the functional spectrum of biallelic variants affecting the NALCN gene, this article broadens the IHPRF1 syndrome’s genotype-phenotype correlation and gives new insight into its pathogenic mechanism, diagnosis, and clinical management.

Abstract The neuronal ceroid lipofuscinosis type 2 (CLN2) is a heterogeneous group of neurodegenerative lysosomal storage disorders caused by autosomal recessive inheritance of two pathogenic variants in trans in the TPP1 gene. Classical late‐infantile CLN2 disease has a very well‐defined natural history. However, a small number of patients with TPP1 enzyme deficiency present a later onset or protracted disease course within this group there are phenotypic variants. Our work aimed to identify pathological variants in the TPP1 gene that conditioned the development of CLN2 disease in Ukrainian patients, to compare these variants with those found in patients from other European and non‐European regions, and to make genotype–phenotype associations for this disease. The phenotypes and genotypes of the 48 CLN2‐affected individuals belonging to 43 families were profiled through clinical data collection, enzyme analysis, and genotyping. In most patients, genotype and phenotype correlation are in keeping with the data of previous studies. The clinical signs of the disease in patients with new, previously undescribed variants, allowed us to augment existing data about genotype–phenotype correlations for CLN2 disease. The combination of genotype and clinical form of the disease demonstrated that predicting the type and clinical course of the disease based on genotype is very complicated. The data we obtained supplements existing information on genotype–phenotypic correlations in this rare disease, which, in turn, lays the foundation for a personalized approach to the management of this disease.