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Abstract Background Maple syrup urine disease (MSUD) is a rare autosomal recessive metabolic disorder caused by variants in any of the following genes: BCKDHA, BCKDHB, and DBT gene. Previous reports have highlighted a variety of common causing genes and variants among different ethnic groups affected by MSUD. This study is the first to describe the molecular characteristics, potential common variants, clinical phenotypes, and treatment outcomes of 20 Thai MSUD patients before the implementation of expanded newborn screening in Thailand. Results A cross-sectional, multicenter study was conducted, including twenty Thai MSUD patients from 1997 to 2023. Most of the patients presented with classic neonatal onset (95%). The mortality rate was 20%, while global developmental delay was observed in 40% of the patients. Variants in the BCKDHB gene were detected in 85% (17/20) of the patients, while the BCKDHA gene accounted for 15% (3/20). The study identified the 11-kb deletion involving 5’UTR, exon 1, and intron 1 in the BCKDHB gene, from a position of g.80102385 to g.80113453 (NC_000006.12), accounting for 50% of all variants (20/40 alleles) in Thai MSUD patients. All patients with the 11-kb deletion in BCKDHB presented with the classic type. The gap-PCR for this common deletion was established in the study. Conclusion This study is the first to describe the clinical and molecular spectrum of Thai MSUD patients before the implementation of expanded NBS. The 11-kb deletion involving exon 1 in the BCKDHB emerges as the most common variant among Thai individuals with MSUD. Furthermore, the gap-PCR test for detecting the 11-kb exon 1 deletion status holds the potential for integration into stepwise molecular analysis following positive expanded newborn screening.

Abstract MRPS23 is a nuclear gene encoding a mitochondrial ribosomal protein. A patient with a mitochondrial disorder was found to carry a variant in MRPS23. More cases are necessary to establish MRPS23 as a mitochondrial disease gene. Of 5134 exomes performed in our center, we identified five independent patients who had similar clinical manifestations and were homozygous for the same germline variant c.119C>T; p.P40L in MRPS23. Detailed clinical findings, mitochondrial enzyme activity assays from cultured skin fibroblasts, PCR-Sanger-sequencing, and variant age estimation were performed. Their available family members were also studied. Eight members homozygous for the MRPS23 p.P40L were identified. All were from Hmong hilltribe. Seven presented with alteration of consciousness and recurrent vomiting, while the eighth who was a younger brother of a proband was found pre-symptomatically. Patients showed delayed growth and development, hearing impairment, hypoglycemia, lactic acidosis, and liver dysfunction. In vitro assays of cultured fibroblasts showed combined respiratory chain complex deficiency with low activities of complexes I and IV. PCR-Sanger-sequencing confirmed the variant, which was estimated to have occurred 1550 years ago. These results establish the MRPS23-associated mitochondrial disorder inherited in an autosomal recessive pattern and provide insight into its clinical and metabolic features.

Abstract Muscular dystrophies and congenital myopathies are heterogeneous groups of inherited muscular disorders. An accurate diagnosis is challenging due to their complex clinical presentations and genetic heterogeneity. This study aimed to determine the utilisation of exome sequencing (ES) for Thai paediatric patients with muscular disorders. Of 176 paediatric patients suspected of genetic/inherited myopathies, 133 patients received a molecular diagnosis after performing conventional investigations, single gene testing, and gene panels. The remaining 43 patients from 42 families could be classified into three groups: Group 1, MLPA-negative Duchenne muscular dystrophy (DMD) with 9 patients (9/43; 21%), Group 2, other muscular dystrophies (MD) with 18 patients (18/43; 42%) and Group 3, congenital myopathies (CM) with 16 patients (16/43; 37%). All underwent exome sequencing which could identify pathogenic variants in 8/9 (89%), 14/18 (78%), and 8/16 (50%), for each Group, respectively. Overall, the diagnostic yield of ES was 70% (30/43) and 36 pathogenic/likely pathogenic variants in 14 genes were identified. 18 variants have never been previously reported. Molecular diagnoses provided by ES changed management in 22/30 (73%) of the patients. Our study demonstrates the clinical utility and implications of ES in inherited myopathies.

Abstract The spectra of underlying genetic variants for various clinical entities including focal segmental glomerulosclerosis (FSGS) vary among different populations. Here we described the clinical and genetic characteristics of biopsy-proven FSGS patients in Thailand. Patients with FSGS pathology, without secondary causes, were included in our study. Clinical laboratory and pathological data were collected. Whole-exome sequencing (WES) was subsequently performed. 53 unrelated FSGS patients were recruited. 35 patients were adults (66.0%), and 51 patients were sporadic cases (96.2%). Clinical diagnosis before kidney biopsy was steroid-resistant nephrotic syndrome (SRNS) in 58.5%, and proteinuric chronic kidney disease in 32.1%. Using WES, disease-associated pathogenic/likely pathogenic (P/LP) variants could be identified in six patients including the two familial cases, making the P/LP detection rate of 11.3% (6/53). Of these six patients, two patients harbored novel variants with one in the COL4A4 gene and one in the MAFB gene. Four other patients carried previously reported variants in the CLCN5, LMX1B, and COL4A4 genes. Four of these patients (4/6) received immunosuppressive medications as a treatment for primary FSGS before genetic diagnosis. All four did not respond to the medications, emphasizing the importance of genetic testing to avoid unnecessary treatment. Notably, the mutation detection rates in adult and pediatric patients were almost identical, at 11.4% and 11.1%, respectively. In conclusion, the overall P/LP variant detection rate by WES in biopsy-proven FSGS patients was 11.3%. The most identified variants were in COL4A4. In addition, three novel variants associated with FSGS were detected.

Abstract Inborn errors of immunity are known to cause not only immunodeficiencies and allergies but also autoimmunity. Leukocyte immunoglobulin-like receptor B1 (LILRB1) is a receptor on leukocytes playing a role in regulating immune responses. No phenotypes have been reported to be caused by germline mutations in LILRB1. We aimed to identify the causative variant in a three-generation family with nine members suffering from one of the three autoimmune diseases—Graves’ disease, Hashimoto's thyroiditis, or systemic lupus erythematosus. Whole-genome linkage study revealed a locus on chromosome 19q13.4 with the maximum LOD score of 2.71. Whole-exome sequencing identified a heterozygous missense variant, c.479G > A (p. G160E) in LILRB1, located within the chromosomal-linked region, in all nine affected members. The variant has never been previously reported. Jurkat cells transfected with the mutant LILRB1, compared with those with the wild-type LILRB1, showed decreased phosphorylation of both LILRB1 and its downstream protein, SHP-1. Flow cytometry was used to study immunophenotype and revealed that LILRB1 was significantly lower on the surface of activated regulatory T lymphocytes (Treg) cells of patients. Single-cell RNA sequencing showed substantially increased M1-like monocytes in peripheral blood mononuclear cells of affected individuals. This study, for the first time, implicates LILRB1 as a new disease gene for autoimmunity.

A heterozygous nonsense variant in the TIGIT gene was identified in a patient in Thailand who had severe COVID-19, resulting in lower TIGIT expression in T cells. The patient’s T cells produced higher levels of cytokines upon stimulation. This mutation causes less-controlled immune responses, which might contribute to COVID-19 severity.

Abstract Background Gaucher disease (GD) is a rare lysosomal storage disorder, characterized by hepatosplenomegaly and pancytopenia, with or without neurologic involvement. The disorder is categorized into three phenotypes: GD type 1 or nonneuronopathic GD; GD type 2 or acute neuronopathic GD; and GD type 3 or chronic neuronopathic GD. The purposes of this study were to describe clinical characteristics of Thai GD in patients diagnosed and/or followed up during 2010–2018 and to perform re-genotyping including analysis of GBA recombinant alleles which had not been investigated in Thai patients before. Results There were 27 patients from seven medical centers, enrolled in the study. All the cases had pediatric onset. GD3 (44.5%) was the most common phenotype, followed by GD2 (40.7%) and GD1 (14.8%), with one case of neonatal GD. The median age of onset for GD1, GD2, and GD3 was 72, 4 and 12 months, respectively, suggesting relatively earlier onset of GD1 and GD3 in Thai patients. All patients with GD1 and most patients with GD3 received ERT. Four patients with GD3 had ERT followed by HSCT. Patients with GD3 who received no or late ERT showed unfavorable outcomes. We identified 14 variants including two novel (p.S384F and p.W533*) and 12 reported pathogenic variants: p.L483P, p.N409S, p.R159W, p.P305A, p.A175G, p.D448H, p.V414L, IVS2+1G>A, IVS6-1G>C, IVS7+1G>C, IVS9-3C>G, and Rec1a. The p.L483P was the most prevalent allele found in this study, at 66% (33/50 alleles), followed by IVS2+1G>A, Rec1a, and IVS6-1G>C. Twenty-four percent of patients were reassigned with validated genotypes, most of whom (4 of 6) were patients with GD2. The [p.S384F + p.W533*] being compounded with p.L483P, was found in the patient with neonatal GD, suggesting that the p.S384F could potentiate the deleterious effect of the p.W533*, and/or vice versa. Conclusions Neuronopathic GD was strikingly prevalent among Thai affected population. Homozygous p.L483P was the most common genotype identified in Thai patients. Recombinant allele Rec1a and splicing mutations were associated with GD2 and severe cases of GD3. Mutation spectrum could be useful for designing stepwise molecular analysis, genetic screenings in population, and new therapeutic research for neuronopathic GD.

Objective: To determine the clinicopathologic features and germline tumor protein p53 (TP53) mutation in children with adrenocortical carcinoma (ACC). Material and Methods: This was a retrospective study. From 2009 to 2018, children with ACC from King Chulalongkorn Memorial Hospital and Phramongkutklao Hospital were enrolled into the study. Clinical presentations and hormonal profiles were recorded. Mutation analyses of the TP53 gene were acquired using the next-generation-sequencing method which was performed for germline samples of all patients and the parents of those who tested positive. Result: Two males and six females with ACC were enrolled into this study. The median age at diagnosis was 25.5 months (range 10 to 67 months). All participants had virilization, either virilization only (n=3) or associated with Cushing (n=5). All participants had had surgery to completely remove all of the tumor and three participants had received adjuvant chemotherapy consisting of etoposide, doxorubicin, and cyclophosphamide. All participants had three different known mutations in the TP53 gene: c.1010G>A (p.R337H), c.916C>T (p.R306*) and c.743G>A (p.R248Q). Two of the three participants with TP53 mutations had pulmonary metastasis. One participant had wild-type TP53 and pulmonary recurrence occurred one year after diagnosis. The median follow-up time was 31 months (range 10 to 168 months. As of this writing, seven participants survived without evidence of recurrence. No second malignancy was found in all participants. One participant who had c.916C>T died of pulmonary metastasis 10 months after diagnosis. Conclusion: We successfully identified three different germline TP53 mutations in patients with ACC. Progression to pulmonary metastasis and recurrence were higher among participants with TP53 mutations. The treatment outcome of childhood ACC was good when surgery and adjuvant chemotherapy were used.

Genetic disorders have been shown to co-occur in individual patient. A Thai boy with features of osteogenesis imperfecta (OI) and combined pituitary hormone deficiency (CPHD) was identified. The causative mutations were investigated by whole exome and Sanger sequencing. Pathogenicity and pathomechanism of the variants were studied by luciferase assay. The proband was found to harbor a novel de novo heterozygous missense mutation, c.1531G > T (p.G511C), in COL1A2 leading to OI and a heterozygous missense variant, c.364C > T (p.R122W), in LHX4. The LHX4 p.R122W has never been reported to cause CPHD. The variant was predicted to be deleterious and found in the highly conserved LIM2 domain of LHX4. The luciferase assays revealed that the p.R122W was unable to activate POU1F1, GH1, and TSHB promoters, validating its pathogenic effect in CPHD. Moreover, the variant did not alter the function of wild-type LHX4, indicating its hypomorphic pathomechanism. In conclusion, the novel de novo heterozygous p.G511C mutation in COL1A2 and the heterozygous pathogenic p.R122W mutation in LHX4 were demonstrated in a patient with OI and CPHD. This study proposes that the mutations in two different genes should be sought in the patients with clinical features unable to be explained by a mutation in one gene. Keywords: Thyroxine, Bisphosphonate, Mutation, Insulin, Skeleton, Growth

Abstract Purpose Our meta-analysis of several ethnic groups (Japanese, Korean, Indian, Brazilian) revealed a significant genome-wide association between cold medicine-related SJS/TEN (CM-SJS/TEN) with severe ocular complications (SOC) and IKZF1 SNPs, suggesting that IKZF1 might be a potential marker for susceptibility to CM-SJS/TEN with SOC. In this study, we examined the association between CM-SJS/TEN with SOC and the IKZF1 SNPs in the Thai population. Methods 57 CM-SJS/TEN with SOC and 171 control samples were collected at Chulalongkorn University and Mahidol University. Genomic DNA samples were genotyped for the IKZF1 SNPs at Kyoto Prefectural University of Medicine in Japan using the TaqMan SNP genotyping assay. Results The four SNPs previously reported to be associated with CM-SJS/TEN with SOC in the Japanese were examined in the Thai samples. Although the number of Thai cases (n = 57) was small, a significant association between CM-SJS/TEN with SOC and IKZF1 SNPs which included rs4917014 (T vs G, OR = 2.9, p = 0.0012, Pc = 0.0049), rs4917129 (T vs C, OR = 2.8, p = 0.0026, Pc = 0.010) and rs10276619 (G vs A, OR = 1.8, p = 0.012, Pc = 0.048) was identified. Conclusion In addition to the Japanese, Korean and Indian populations, Thai cases with CM-SJS/TEN and SOC were significantly associated with IKZF1 SNPs. With our previous report of the critical role of IKZF1 in mucocutaneous inflammation, these results suggest that IKZF1 is important in the pathogenesis of CM-SJS/TEN with SOC.

Background: Genetic tests for primary immunodeficiency disorders (PIDs) are expensive, time-consuming, and not easily accessible in developing countries. Therefore, we studied the feasibility of a customized single nucleotide variant (SNV) microarray that we developed to detect disease-causing variants and copy number variation (CNV) in patients with PIDs for only 40 Euros.Methods: Probes were custom-designed to genotype 9,415 variants of 277 PID-related genes, and were added to the genome-wide Illumina Global Screening Array (GSA). Data analysis of GSA was performed using Illumina GenomeStudio 2.0, Biodiscovery Nexus 10.0, and R-3.4.4 software. Validation of genotype calling was performed by comparing the GSA with whole-genome sequencing (WGS) data of 56 non-PID controls. DNA samples of 95 clinically diagnosed PID patients, of which 60 patients (63%) had a genetically established diagnosis (by Next-Generation Sequencing (NGS) PID panels or Sanger sequencing), were analyzed to test the performance of the GSA. The additional SNVs detected by GSA were validated by Sanger sequencing.Results: Genotype calling of the customized array had an accuracy rate of 99.7%. The sensitivity for detecting rare PID variants was high (87%). The single sample replication in two runs was high (94.9%). The customized GSA was able to generate a genetic diagnosis in 37 out of 95 patients (39%). These 37 patients included 29 patients in whom the genetic variants were confirmed by conventional methods (26 patients by SNV and 3 by CNV analysis), while in 8 patients a new genetic diagnosis was established (6 patients by SNV and 2 patients suspected for leukemia by CNV analysis). Twenty-eight patients could not be detected due to the limited coverage of the custom probes. However, the diagnostic yield can potentially be increased when newly updated variants are added.Conclusion: Our robust customized GSA seems to be a promising first-line rapid screening tool for PIDs at an affordable price, which opens opportunities for low-cost genetic testing in developing countries. The technique is scalable, allows numerous new genetic variants to be added, and offers the potential for genetic testing not only in PIDs, but also in many other genetic diseases.

Abstract Background WNT1 mutations cause bone fragility as well as brain anomalies. There are some reported cases of WNT1 mutations with normal cognition. Genotype and phenotype correlation of WNT1 mutations has not been established. Case presentation Here we present two female siblings with osteogenesis imperfecta (OI) born to a consanguineous couple. Both sustained severe bone deformities. However, only the younger had severe brain anomalies resulting in an early death from pneumonia, while the older had normal intellectual development. Next generation sequencing showed a homozygous mutation, c.6delG, p.Leu3Serfs*36 in WNT1. To our knowledge, it is the most 5′ truncating mutation to date. Conclusion This report emphasizes the intrafamilial variability of brain anomalies found in this OI type and suggests that WNT1 may not be necessary for normal human cognitive development.

Abstract Background Alu elements are a group of repetitive elements that can influence gene expression through CpG residues and transcription factor binding. Altered gene expression and methylation profiles have been reported in various tissues and cell lines from individuals with autism spectrum disorder (ASD). However, the role of Alu elements in ASD remains unclear. We thus investigated whether Alu elements are associated with altered gene expression profiles in ASD. Methods We obtained five blood-based gene expression profiles from the Gene Expression Omnibus database and human Alu-inserted gene lists from the TranspoGene database. Differentially expressed genes (DEGs) in ASD were identified from each study and overlapped with the human Alu-inserted genes. The biological functions and networks of Alu-inserted DEGs were then predicted by Ingenuity Pathway Analysis (IPA). A combined bisulfite restriction analysis of lymphoblastoid cell lines (LCLs) derived from 36 ASD and 20 sex- and age-matched unaffected individuals was performed to assess the global DNA methylation levels within Alu elements, and the Alu expression levels were determined by quantitative RT-PCR. Results In ASD blood or blood-derived cells, 320 Alu-inserted genes were reproducibly differentially expressed. Biological function and pathway analysis showed that these genes were significantly associated with neurodevelopmental disorders and neurological functions involved in ASD etiology. Interestingly, estrogen receptor and androgen signaling pathways implicated in the sex bias of ASD, as well as IL-6 signaling and neuroinflammation signaling pathways, were also highlighted. Alu methylation was not significantly different between the ASD and sex- and age-matched control groups. However, significantly altered Alu methylation patterns were observed in ASD cases sub-grouped based on Autism Diagnostic Interview-Revised scores compared with matched controls. Quantitative RT-PCR analysis of Alu expression also showed significant differences between ASD subgroups. Interestingly, Alu expression was correlated with methylation status in one phenotypic ASD subgroup. Conclusion Alu methylation and expression were altered in LCLs from ASD subgroups. Our findings highlight the association of Alu elements with gene dysregulation in ASD blood samples and warrant further investigation. Moreover, the classification of ASD individuals into subgroups based on phenotypes may be beneficial and could provide insights into the still unknown etiology and the underlying mechanisms of ASD.

Abstract Background Hyperphenylalaninemia (HPA) can be classified into phenylketonuria (PKU) which is caused by mutations in the phenylalanine hydroxylase (PAH) gene, and BH4 deficiency caused by alterations in genes involved in tetrahydrobiopterin (BH4) biosynthesis pathway. Dietary restriction of phenylalanine is considered to be the main treatment of PKU to prevent irreversible intellectual disability. However, the same dietary intervention in BH4 deficiency patients is not as effective, as BH4 is also a cofactor in many neurotransmitter syntheses. Method We utilized next generation sequencing (NGS) technique to investigate four unrelated Thai patients with hyperphenylalaninemia. Result We successfully identified all eight mutant alleles in PKU or BH4-deficiency associated genes including three novel mutations, one in PAH and two in PTS, thus giving a definite diagnosis to these patients. Appropriate management can then be provided. Conclusion This study identified three novel mutations in either the PAH or PTS gene and supported the use of NGS as an alternative molecular genetic approach for definite diagnosis of hyperphenylalaninemia, thus leading to proper management of these patients in Thailand.

Two clones of human induced pluripotent stem cells (iPSCs) were generated from dermal fibroblasts isolated from a one-year-old Thai patient with X-linked osteogenesis imperfecta. The patient harbored a mutation, p.N459S, in the MBTPS2 gene. The cells were reprogrammed using an integration-free Sendai virus containing KLF4, c-MYC, OCT4 and SOX2. Both of the established iPSC lines (MDCUi001-A and MDCUi001-B) maintained normal karyotype, expressed pluripotent markers and differentiated into all three germ layers.

Osteogenesis imperfecta (OI) is genetically linked to autosomal dominant or autosomal recessive mutations. Here, Marini et al. describe two families with X-chromosome-linked OI with mutations in MBTPS2 that alter regulated intramembrane proteolysis and subsequent defects in collagen crosslinking and osteoblast function.

Cerebrospinal fluid flow is crucial for neurodevelopment and homeostasis of the ventricular system of the brain, with localized flow being established by the polarized beating of the ependymal cell (EC) cilia. Here, we report a homozygous one base-pair deletion, c.1193delT (p.Leu398Glnfs*2), in the Kinesin Family Member 6 (KIF6) gene in a child displaying neurodevelopmental defects and intellectual disability. To test the pathogenicity of this novel human KIF6 mutation we engineered an analogous C-terminal truncating mutation in mouse. These mutant mice display severe, postnatal-onset hydrocephalus. We generated a Kif6-LacZ transgenic mouse strain and report expression specifically and uniquely within the ependymal cells (ECs) of the brain, without labeling other multiciliated mouse tissues. Analysis of Kif6 mutant mice with scanning electron microscopy (SEM) and immunofluorescence (IF) revealed specific defects in the formation of EC cilia, without obvious effect of cilia of other multiciliated tissues. Dilation of the ventricular system and defects in the formation of EC cilia were also observed in adult kif6 mutant zebrafish. Finally, we report Kif6-GFP localization at the axoneme and basal bodies of multi-ciliated cells (MCCs) of the mucociliary Xenopus epidermis. Overall, this work describes the first clinically-defined KIF6 homozygous null mutation in human and defines KIF6 as a conserved mediator of neurological development with a specific role for EC ciliogenesis in vertebrates.

Background. Age, race, and analytic method influence levels of blood amino acids, of which reference intervals are required for the diagnosis and management of inherited metabolic disorders. Objectives. To establish age-specific reference intervals for blood amino acids in Thai pediatric population measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). Methods. A cross-sectional study of 277 healthy children from birth to 12 years was conducted. Anthropometric, clinical, and dietary information were recorded. Dried blood spots on a filtered paper were used for measurement by derivatized LC-MS/MS. Factors that might affect amino acids such as fasting time and dietary intake were analyzed using quantile regression analysis. Results. Levels of thirteen blood amino acids were reported as median and interval from 2.5th–97.5th percentiles. Compared with those of Caucasian, most blood amino acid levels of Thai children were higher. Compared with a previous study using HPLC in Thai children, many amino acid levels are different. Glycine, alanine, leucine/isoleucine, and glutamic acid sharply decreased after birth. Citrulline, arginine, and methionine stayed low from birth throughout childhood, whereas phenylalanine was at middle level and slightly increased during preadolescence. Conclusion. Reference intervals of age-specific blood amino acids using LC-MS/MS were established in the Thai pediatric population. They diverge from previous studies, substantiating the recommendation that, for the optimal clinical practice, age-specific reference intervals of amino acids should be designated for the particular population and analysis method.

BACKGROUND:The exact cause and mechanisms underlying the pathobiology of autism spectrum disorder (ASD) remain unclear. Dysregulation of long interspersed element-1 (LINE-1) has been reported in the brains of ASD-like mutant mice and ASD brain tissues. However, the role and methylation of LINE-1 in individuals with ASD remain unclear. In this study, we aimed to investigate whether LINE-1 insertion is associated with differentially expressed genes (DEGs) and to assess LINE-1 methylation in ASD. METHODS:To identify DEGs associated with LINE-1 in ASD, we reanalyzed previously published transcriptome profiles and overlapped them with the list of LINE-1-containing genes from the TranspoGene database. An Ingenuity Pathway Analysis (IPA) of DEGs associated with LINE-1 insertion was conducted. DNA methylation of LINE-1 was assessed via combined bisulfite restriction analysis (COBRA) of lymphoblastoid cell lines from ASD individuals and unaffected individuals, and the methylation levels were correlated with the expression levels of LINE-1 and two LINE-1-inserted DEGs, C1orf27 and ARMC8. RESULTS:We found that LINE-1 insertion was significantly associated with DEGs in ASD. The IPA showed that LINE-1-inserted DEGs were associated with ASD-related mechanisms, including sex hormone receptor signaling and axon guidance signaling. Moreover, we observed that the LINE-1 methylation level was significantly reduced in lymphoblastoid cell lines from ASD individuals with severe language impairment and was inversely correlated with the transcript level. The methylation level of LINE-1 was also correlated with the expression of the LINE-1-inserted DEG C1orf27 but not ARMC8. CONCLUSIONS:In ASD individuals with severe language impairment, LINE-1 methylation was reduced and correlated with the expression levels of LINE-1 and the LINE-1-inserted DEG C1orf27. Our findings highlight the association of LINE-1 with DEGs in ASD blood samples and warrant further investigation. The molecular mechanisms of LINE-1 and the effects of its methylation in ASD pathobiology deserve further study.

Abstract Osteogenesis imperfecta (OI) is genetically heterogeneous. Mutations in COL1A1 and COL1A2 are responsible for at least 90% of the cases, which are transmitted in an autosomal dominant manner or are de novo events. We identified a Thai boy with OI whose parents were first cousins. Because the proband was the product of a consanguineous marriage, we hypothesized that he might be homozygous for a mutation in a known gene causing a recessive form of OI. Using whole exome sequencing (WES), we did not find any pathogenic mutations in any known gene responsible for an autosomal recessive form of OI. Instead, we identified a COL1A1 frameshift mutation, c.1290delG (p.Gly431Valfs*110) in heterozygosis. By Sanger sequencing, the mutation was confirmed in the proband, and not detected in his parents, indicating that it was a de novo mutation. These findings had implication for genetic counseling. In conclusion, we expanded the mutational spectrum of COL1A1 and provided another example of a de novo pathogenic mutation in heterozygosis in a patient born to consanguineous parents.

Introduction. Maple syrup urine disease (MSUD) is an inborn error of branched chain amino acids (BCAAs) metabolism. We report an infant with MSUD who developed 2 episodes of cutaneous lesions as a result of isoleucine deficiency and zinc deficiency, respectively. Case Presentation. A 12-day-old male infant was presented with poor milk intake and lethargy. The diagnosis of MSUD was made based on clinical and biochemical data. Management and Outcome. Specific dietary restriction of BCAAs was given. Subsequently, natural protein was stopped as the patient developed hospital-acquired infections which resulted in an elevation of BCAAs. Acrodermatitis dysmetabolica developed and was confirmed to be from isoleucine deficiency. At the age of 6 months, the patient developed severe lethargy and was on natural protein exclusion for an extended period. Despite enteral supplementation of zinc sulfate, cutaneous manifestations due to zinc deficiency occurred. Discussion. Skin lesions in MSUD patients could arise from multiple causes. Nutritional deficiency including isoleucine and zinc deficiencies can occur and could complicate the treatment course as a result of malabsorption, even while on enteral supplementation. Parenteral nutrition should be considered and initiated accordingly. Clinical status, as well as BCAA levels, should be closely monitored in MSUD patients.

Congenital heart defects (CHD) occur in 40% of patients with trisomy 21, while the other 60% have a structurally normal heart. This suggests that the increased dosage of genes on chromosome 21 is a risk factor for abnormal heart development. Interaction of genes on chromosome 21 or their gene products with certain alleles of genes on other chromosomes could contribute to CHD. Here, we identified a pair of monozygotic twins with trisomy 21 but discordant for a ventricular septal defect and epilepsy. Twin-zygosity was confirmed by microsatellite genotyping. We hypothesized that some genetic differences from post-twinning mutations caused the discordant phenotypes. Thus, next generation sequencing (NGS) technologies were applied to sequence both whole genome and exome of their leukocytes. The post-analyses of the sequencing data revealed 21 putative discordant exonic variants between the twins from either genome or exome data. However, of the 15 variants chosen for validation with conventional Sanger sequencing, these candidate variants showed no differences in both twins. The fact that no discordant DNA variants were found suggests that sequence differences of DNA from leukocytes of monozygotic twins might be extremely rare. It also emphasizes the limitation of the current NGS technology in identifying causative genes for discordant phenotypes in monozygotic twins.