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Introduction: Developmental and epileptic encephalopathy 9 (DEE9) is caused by pathogenic variants in the PCDH19 gene. The clinical features include early-onset seizures that are often provoked by fever and display clustered seizures, mild to profound intellectual disability, autistic traits, and behavioral disturbances. DEE9 is characterized by an unusual X-linked pattern where heterozygous females or rarely mosaic hemizygous males are affected, but hemizygous males and homozygous females are asymptomatic. In recent years, an increasing number of female and male patients with PCDH19-related epilepsy and symptoms have been reported. Methods: Here, we report two additional female patients with DEE9 who are siblings. After analyzing karyotype testing results, whole-exome sequencing (WES) was performed for the proband. Then, Sanger sequencing was carried out for proband, her affected sister, and parents. Results: Sequencing results revealed that our two patients had a heterozygous frameshift variant (NM_001184880.2: c.1091delC, p.P364Rfs*4) in the PCDH19 gene. We also reviewed previously reported cases with this mutation in detail. Conclusion: This is the first report of germline mosaicism in the PCDH19 gene in the Iranian population and expanded the phenotypic spectrum of DEE9. Genetic testing has become an effective way of determining the diagnosis. Parental germline mosaicism should be considered when providing genetic counseling for X-linked/autosomal dominant disorders. This report also emphasizes the importance of considering prenatal diagnosis (PND) in such cases. [ABSTRACT FROM AUTHOR]

Background: Brain–lung–thyroid syndrome (BLTS) is caused by NKX2-1 haploinsufficiency, resulting in chorea/choreoathetosis, respiratory problems, and hypothyroidism. Genes interacting with NKX2-1 mutants influence its phenotypic variability. We report a novel NKX2-1 missense variant and the modifier function of TAZ/WWTR1 in BLTS. Methods: A child with BLTS underwent next-generation sequencing panel testing for thyroid disorders. His family was genotyped for NKX2-1 variants and screened for germline mosaicism. Mutant NKX2-1 was generated, and transactivation assays were performed on three NKX2-1 target gene promoters. DNA binding capacity and protein–protein interaction were analyzed. Results: The patient had severe BLTS and carried a novel missense variant c.632A>G (p.N211S) in NKX2-1, which failed to bind to specific DNA promoters, reducing their transactivation. TAZ cotransfection did not significantly increase transcription of these genes, although the variant retained its ability to bind to TAZ. Conclusions: We identify a novel pathogenic NKX2-1 variant that causes severe BLTS and is inherited through germline mosaicism. The mutant lacks DNA-binding capacity, impairing transactivation and suggesting that NKX2-1 binding to DNA is essential for TAZ-mediated transcriptional rescue. [ABSTRACT FROM AUTHOR]

Objective: Facioscapulohumeral muscular dystrophy type 1 (FSHD1) is one of the most common forms of autosomal-dominant muscular dystrophies characterized by variable disease penetrance due to shortened D4Z4 repeat units on 4q35. Themolecular diagnosis of FSHD1 is usuallymade by Southern blotting, which is complex, time-consuming, and lacks clinical practicality. Therefore, in this study, optical genome mapping (OGM) is employed for the genetic diagnosis of FSHD1. Furthermore, epigenetic heterogeneity is determined from methylation analysis. Methods: Genomic DNA samples from four members of the same family were subjected to whole-exome sequencing. OGM was used to identify structural variations in D4Z4, while sodium bisulfite sequencing helped identify the methylation levels of CpG sites in a region located distally to the D4Z4 array. A multidisciplinary team collected the clinical data, and comprehensive family analyses aided in the assessment of phenotypes and genotypes. Results: Whole-exome sequencing did not reveal variants related to clinical phenotypes in the patients. OGM showed that the proband was a compound heterozygote for the 4qA allele with four and eight D4Z4 repeat units, whereas the affected younger brother had only one 4qA allele with four D4Z4 repeat units. Both the proband and her younger brother were found to display asymmetric weakness predominantly involving the facial, shoulder girdle, and upper arm muscles, whereas the younger brother had more severe clinical symptoms. The proband's father, who was found to be normal after a neurological examination, also carried the 4qA allele with eight D4Z4 repeat units. The unaffected mother exhibited 49 D4Z4 repeat units of the 4qA allele and a minor mosaic pattern with four D4Z4 repeat units of the 4qA allele. Consequently, the presence of the 4qA allele in the four D4Z4 repeat units strongly pointed to the occurrence of maternal germline mosaicism. The CpG6 methylation levels were lower in symptomatic patients compared to those in the asymptomatic parents. The older sister had lower clinical scores and ACSS and higher CpG6 methylation levels than that of her younger brother. Conclusions: In this study, two siblings with FSHD1 with phenotypically normal parents were identified by OGM. Our findings suggest that the 4qA allele of four D4Z4 repeats was inherited through maternal germline mosaicism. The clinical phenotype heterogeneity is influenced by the CpG6 methylation levels. The results of this study greatly aid in the molecular diagnosis of FSHD1 and in also understanding the clinical phenotypic variability underlying the disease. [ABSTRACT FROM AUTHOR]

Sporadic hemophilia A (HA) enables the persistence of HA in the population. F8 gene inversion originates mainly in male germ cells during meiosis. To date, no studies have shown the origin and timing of HA sporadic noninversion variants (NIVs); herein, we assume that HA-sporadic NIVs are generated as a de novo variant. Of the 125 registered families with HA, 22 were eligible for inclusion. We conducted a linkage analysis using F8 gene markers and amplification refractory mutation system–quantitative polymerase chain reaction to confirm the origin of the sporadic NIVs (~0% mutant cells) or the presence of a mosaic variant, which requires further confirmation of the origin in the parent. Nine mothers, four maternal grandmothers, and six maternal grandfathers were confirmed to be the origin of sporadic NIVs, which most likely occurred in the zygote within the first few cell divisions and in single sperm cells, respectively. Three mothers had mosaic variants, which most likely occurred early in postzygotic embryogenesis. All maternal grandparents were free from sporadic NIV. In conclusion, F8 NIVs in sporadic HA were found to be caused primarily by de novo variants. Our studies are essential for understanding the genetic pathogenesis of HA and improving current genetic counseling. [ABSTRACT FROM AUTHOR]

Abstract Background Preimplantation genetic testing (PGT) for monogenic disorders (PGT-M) for germline mosaicism was previously highly dependent on polymerase chain reaction (PCR)-based directed mutation detection combined with linkage analysis of short tandem repeats (STRs). However, the number of STRs is usually limited. In addition, designing suitable probes and optimizing the reaction conditions for multiplex PCR are time-consuming and laborious. Here, we evaluated the effectiveness of next generation sequencing (NGS)-based haplotype linkage analysis in PGT of germline mosaicism. Methods PGT-M with NGS-based haplotype linkage analysis was performed for two families with maternal germline mosaicism for an X-linked Duchenne muscular dystrophy (DMD) mutation (del exon 45–50) or an autosomal TSC1 mutation (c.2074C > T). Trophectoderm biopsy and multiple displacement amplification (MDA) were performed for a total of nine blastocysts. NGS and Sanger sequencing were performed in genomic DNA of family members and embryonic MDA products to detect DMD deletion and TSC1 mutation, respectively. Single nucleotide polymorphism (SNP) sites closely linked to pathogenic mutations were detected with NGS and served in haplotype linkage analysis. NGS-based aneuploidy screening was performed for all embryos to reduce the risk of pregnancy loss. Results All nine blastocytes showed conclusive PGT results. Each family underwent one or two frozen-thawed embryo transfer cycles to obtain a clinical pregnancy, and the prenatal diagnosis showed that the fetus was genotypically normal and euploid for both families. Conclusions NGS-SNP could effectively realize PGT for germline mosaicism. Compared with PCR-based methods, the NGS-SNP method with increased polymorphic informative markers can achieve a greater diagnostic accuracy. Further studies are warranted to verify the effectiveness of NGS-based PGT of germline mosaicism cases in the absence of surviving offsprings.

Background: KIF2A‐related tubulinopathy (MIM: #615411) is a very rare disorder that was clinically characterized as microcephaly, epilepsy, motor developmental disorder (MDD), and various malformations of cortical development, but intellectual disability (ID) or global developmental delay (GDD) was rarely reported in the patients. Methods: Quad whole‐exome sequencing (WES) was performed on the proband, the older brother, and their parents. Sanger sequencing was used to verify the candidate gene variant. Results: The proband, a 23‐month‐old boy, was previously diagnosed with GDD, and his brother, aged nine years, had ID; both were born to a healthy couple. Quad‐WES detected a novel heterozygous KIF2A variant, c.1318G>A (p.G440R), in both the brothers but not in the parents. In‐silico analysis revealed that the variants G440R and G318R (which were previously reported in the only reported patient with GDD) lead to markedly enlarged side chains and hinder ATP's emplacement in the NBD pocket. Conclusions: The type of KIF2A variants that sterically hinder ATP emplacing in KIF2A NBD pocket may be associated with the intellectual disability phenotype; however, further studies are needed. Findings in this case also suggest a rare parental germline mosaicism of KIF2A G440R. [ABSTRACT FROM AUTHOR]

Abstract Background KIF2A‐related tubulinopathy (MIM: #615411) is a very rare disorder that was clinically characterized as microcephaly, epilepsy, motor developmental disorder (MDD), and various malformations of cortical development, but intellectual disability (ID) or global developmental delay (GDD) was rarely reported in the patients. Methods Quad whole‐exome sequencing (WES) was performed on the proband, the older brother, and their parents. Sanger sequencing was used to verify the candidate gene variant. Results The proband, a 23‐month‐old boy, was previously diagnosed with GDD, and his brother, aged nine years, had ID; both were born to a healthy couple. Quad‐WES detected a novel heterozygous KIF2A variant, c.1318G>A (p.G440R), in both the brothers but not in the parents. In‐silico analysis revealed that the variants G440R and G318R (which were previously reported in the only reported patient with GDD) lead to markedly enlarged side chains and hinder ATP's emplacement in the NBD pocket. Conclusions The type of KIF2A variants that sterically hinder ATP emplacing in KIF2A NBD pocket may be associated with the intellectual disability phenotype; however, further studies are needed. Findings in this case also suggest a rare parental germline mosaicism of KIF2A G440R.

Background: Preimplantation genetic testing (PGT) for monogenic disorders (PGT-M) for germline mosaicism was previously highly dependent on polymerase chain reaction (PCR)-based directed mutation detection combined with linkage analysis of short tandem repeats (STRs). However, the number of STRs is usually limited. In addition, designing suitable probes and optimizing the reaction conditions for multiplex PCR are time-consuming and laborious. Here, we evaluated the effectiveness of next generation sequencing (NGS)-based haplotype linkage analysis in PGT of germline mosaicism. Methods: PGT-M with NGS-based haplotype linkage analysis was performed for two families with maternal germline mosaicism for an X-linked Duchenne muscular dystrophy (DMD) mutation (del exon 45–50) or an autosomal TSC1 mutation (c.2074C > T). Trophectoderm biopsy and multiple displacement amplification (MDA) were performed for a total of nine blastocysts. NGS and Sanger sequencing were performed in genomic DNA of family members and embryonic MDA products to detect DMD deletion and TSC1 mutation, respectively. Single nucleotide polymorphism (SNP) sites closely linked to pathogenic mutations were detected with NGS and served in haplotype linkage analysis. NGS-based aneuploidy screening was performed for all embryos to reduce the risk of pregnancy loss. Results: All nine blastocytes showed conclusive PGT results. Each family underwent one or two frozen-thawed embryo transfer cycles to obtain a clinical pregnancy, and the prenatal diagnosis showed that the fetus was genotypically normal and euploid for both families. Conclusions: NGS-SNP could effectively realize PGT for germline mosaicism. Compared with PCR-based methods, the NGS-SNP method with increased polymorphic informative markers can achieve a greater diagnostic accuracy. Further studies are warranted to verify the effectiveness of NGS-based PGT of germline mosaicism cases in the absence of surviving offsprings. [ABSTRACT FROM AUTHOR]

Pediatric cardiomyopathies (CM) are rare and challenging to diagnose due to the complex and mixed phenotypes. With the advent of next-generation sequencing (NGS), variants in several genes associated with CM have been identified, such as Troponin C (TnC), encoded by the TNNC1 gene. De novo variants in TNNC1 have been associated with different types of CM, including dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). The American College of Medical Genetics and Genomics recently added TNNC1 to their recommended list of genes for reporting secondary findings. In this study, we report a de novo variant, c.100G > C (p.Gly34Arg) in the TNNC1 gene identified in three siblings with a diagnosis of severe DCM causing infant death for one of the siblings and stillbirth in the other two pregnancies. The identification of the same de novo variant in all affected siblings is suggestive of germline mosaicism in this family. [ABSTRACT FROM AUTHOR]

Sporadic hemophilia A (HA) enables the persistence of HA in the population. F8 gene inversion originates mainly in male germ cells during meiosis. To date, no studies have shown the origin and timing of HA sporadic noninversion variants (NIVs); herein, we assume that HA-sporadic NIVs are generated as a de novo variant. Of the 125 registered families with HA, 22 were eligible for inclusion. We conducted a linkage analysis using F8 gene markers and amplification refractory mutation system–quantitative polymerase chain reaction to confirm the origin of the sporadic NIVs (~0% mutant cells) or the presence of a mosaic variant, which requires further confirmation of the origin in the parent. Nine mothers, four maternal grandmothers, and six maternal grandfathers were confirmed to be the origin of sporadic NIVs, which most likely occurred in the zygote within the first few cell divisions and in single sperm cells, respectively. Three mothers had mosaic variants, which most likely occurred early in postzygotic embryogenesis. All maternal grandparents were free from sporadic NIV. In conclusion, F8 NIVs in sporadic HA were found to be caused primarily by de novo variants. Our studies are essential for understanding the genetic pathogenesis of HA and improving current genetic counseling.

Congenital hyperinsulinism is the most common cause of persistent hypoglycemia in early infancy. Mutations in the gene for heterozygous hepatocyte nuclear transcription factor 4-alpha (HNF4A) account for approximately 5% of cases and are inherited in an autosomal dominant fashion or arise as de novo mutations. This case describes a unique presentation of parental gonadal, or germline, mosaicism as the suspected inheritance pattern for siblings with congenital hyperinsulinism caused by HNF4A mutations. Two siblings presented with hypoglycemia in the first hours of life and were subsequently confirmed to have hyperinsulinism. In each patient, glycemic control was achieved at relatively low doses of diazoxide. Both siblings tested positive for the same HNF4A mutation, whereas the parents tested negative for HNF4A mutations. Gonadal, or germline, mosaicism became the presumed leading diagnosis, given 2 unaffected parents with 2 children with congenital hyperinsulinism. The older sibling demonstrated additional clinical features of liver disease and renal Fanconi syndrome, both of which are associated with HNF4A mutations. Genetic testing plays an important role in the diagnosis and management of congenital hyperinsulinism. HNF4A mutations may arise by a range of mechanisms, including gonadal, or germline, mosaicism. HNF4A mutations have phenotypic variance that may affect multiple organ systems at any age. [ABSTRACT FROM AUTHOR]

Malan syndrome is an autosomal dominant disorder caused by pathogenic variants in NFIX with less than 100 cases reported thus far. NFIX is important for stem cell proliferation, quiescence, and differentiation during development and its protein plays a role in replication, signal transduction, and transcription. As a result of pathogenic variants, symptoms of Malan syndrome include overgrowth, intellectual disability, speech delay, and dysmorphic features. Currently, the recurrence risk for this disorder is indicated at less than 1%, standard for de novo autosomal dominant disorders. Herein, we report an additional set of sisters with the same novel pathogenic variant in NFIX and clinical features consistent with Malan syndrome providing evidence of germline mosaicism. Considering the rarity of this condition in conjunction with three previous reports of germline mosaicism, it is worthwhile to investigate and re-evaluate the proper recurrence risk for this condition. This discovery would be paramount for family planning and genetic counseling practices in families with affected individuals. [ABSTRACT FROM AUTHOR]

Background: Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) results from haploinsufficiency of the mesenchymal transcription factor FOXF1 gene. To date, only one case of an ACDMPV‐causative CNV deletion inherited from a very‐low level somatic mosaic mother has been reported. Methods: Clinical, histopathological, and molecular studies, including whole genome sequencing, chromosomal microarray analysis, qPCR, and Sanger sequencing, followed by in vitro fertilization (IVF) with preimplantation genetic testing (PGT) were used to study a family with a deceased neonate with ACDMPV. Results: A pathogenic CNV deletion of the lung‐specific FOXF1 enhancer in the proband was found to be inherited from an unaffected mother, 36% mosaic for this deletion in her peripheral blood cells. The qPCR analyses of saliva, buccal cells, urine, nail, and hair samples revealed 19%, 18%, 15%, 19%, and 27% variant allele fraction, respectively, indicating a high recurrence risk. Grandparental studies revealed that the deletion arose on the mother's paternal chromosome 16. PGT studies revealed 44% embryos with the deletion, reflecting high‐level germline mosaicism. Conclusion: Our data further demonstrate the importance of parental testing in ACDMPV families and reproductive usefulness of IVF with PGT in families with high‐level parental gonosomal mosaicism. [ABSTRACT FROM AUTHOR]

Classical Ehlers–Danlos syndrome (cEDS) is a rare inherited autosomal dominant connective tissue disorder with core clinical features including skin hyperextensibility, abnormal scarring, and generalized joint hypermobility. Classical EDS is predominantly caused by small pathogenic variants in the genes COL5A1 and COL5A2 and occasionally by a COL1A1 point mutation p.(Arg312Cys), while gross deletions or duplications are uncommon. Gonosomal mosaicism is thought to be exceedingly rare with only two cases reported in the literature. We report a child with cEDS due to a rare gross deletion of exons 2–65 in the COL5A1 gene, inherited from an unaffected mosaic father. The level of mosaicism in the father was approximately 43% in leucocyte cells and 30% in DNA extracted from skin. Our results expand the allelic spectrum of cEDS variants and suggest that parental mosaicism needs to be considered in patients with suspected cEDS, given its implication for genetic counseling. Classical Ehlers–Danlos syndrome is typically caused by point mutations and small insertion/deletions. We report a case of a large multi‐exon deletion, inherited from an unaffected father who was mosaic for the deletion, with a relatively high level of mosaicism. Gonosomal mosaicism should be considered when discussing recurrence risks in families. [ABSTRACT FROM AUTHOR]

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by severe developmental delay or intellectual disability caused by either disruption of the maternal UBE3A gene or deletion in the maternal 15q11-q13. Diagnosis of AS in two siblings with normal four-generation history was confirmed through a staged genetic evaluation, G-banding karyotype, Fluorescence in situ Hybridization analysis, and methylation pattern in 15q11-q13. Despite detecting impaired methylation patterns in the region of interest, distinguishing the imprinting defects from uniparental disomy (UPD) was not feasible since we did not have access to the parents' sample. However, regarding the low risk of AS recurrence within families with UPD in the literature and the healthy family history, mosaicism of cryptic imprinting center deletion in the mother's germline should be the most probable cause of AS recurrence in our cases. [ABSTRACT FROM AUTHOR]

Malan syndrome is an autosomal dominant disorder caused by pathogenic variants in NFIX with less than 100 cases reported thus far. NFIX is important for stem cell proliferation, quiescence, and differentiation during development and its protein plays a role in replication, signal transduction, and transcription. As a result of pathogenic variants, symptoms of Malan syndrome include overgrowth, intellectual disability, speech delay, and dysmorphic features. Currently, the recurrence risk for this disorder is indicated at less than 1%, standard for de novo autosomal dominant disorders. Herein, we report an additional set of sisters with the same novel pathogenic variant in NFIX and clinical features consistent with Malan syndrome providing evidence of germline mosaicism. Considering the rarity of this condition in conjunction with three previous reports of germline mosaicism, it is worthwhile to investigate and re-evaluate the proper recurrence risk for this condition. This discovery would be paramount for family planning and genetic counseling practices in families with affected individuals.

Abstract Background Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) results from haploinsufficiency of the mesenchymal transcription factor FOXF1 gene. To date, only one case of an ACDMPV‐causative CNV deletion inherited from a very‐low level somatic mosaic mother has been reported. Methods Clinical, histopathological, and molecular studies, including whole genome sequencing, chromosomal microarray analysis, qPCR, and Sanger sequencing, followed by in vitro fertilization (IVF) with preimplantation genetic testing (PGT) were used to study a family with a deceased neonate with ACDMPV. Results A pathogenic CNV deletion of the lung‐specific FOXF1 enhancer in the proband was found to be inherited from an unaffected mother, 36% mosaic for this deletion in her peripheral blood cells. The qPCR analyses of saliva, buccal cells, urine, nail, and hair samples revealed 19%, 18%, 15%, 19%, and 27% variant allele fraction, respectively, indicating a high recurrence risk. Grandparental studies revealed that the deletion arose on the mother's paternal chromosome 16. PGT studies revealed 44% embryos with the deletion, reflecting high‐level germline mosaicism. Conclusion Our data further demonstrate the importance of parental testing in ACDMPV families and reproductive usefulness of IVF with PGT in families with high‐level parental gonosomal mosaicism.

Abstract Classical Ehlers–Danlos syndrome (cEDS) is a rare inherited autosomal dominant connective tissue disorder with core clinical features including skin hyperextensibility, abnormal scarring, and generalized joint hypermobility. Classical EDS is predominantly caused by small pathogenic variants in the genes COL5A1 and COL5A2 and occasionally by a COL1A1 point mutation p.(Arg312Cys), while gross deletions or duplications are uncommon. Gonosomal mosaicism is thought to be exceedingly rare with only two cases reported in the literature. We report a child with cEDS due to a rare gross deletion of exons 2–65 in the COL5A1 gene, inherited from an unaffected mosaic father. The level of mosaicism in the father was approximately 43% in leucocyte cells and 30% in DNA extracted from skin. Our results expand the allelic spectrum of cEDS variants and suggest that parental mosaicism needs to be considered in patients with suspected cEDS, given its implication for genetic counseling.

Background: De novo variants are a common cause to rare intellectual disability syndromes, associated with low recurrence risk. However, when such variants occur pre‐zygotically in parental germ cells, the recurrence risk might be higher. Still, the recurrence risk estimates are mainly based on empirical data and the prevalence of germline mosaicism is often unknown. Methods: To establish the prevalence of mosaicism in parents of children with intellectual disability syndromes caused by de novo variants, we performed droplet digital PCR on DNA extracted from blood (43 trios), and sperm (31 fathers). Results: We detected low‐level mosaicism in sperm‐derived DNA but not in blood in the father of a child with Kleefstra syndrome caused by an EHMT1 variant. Additionally, we found a higher level of paternal mosaicism in sperm compared to blood in the father of a child with Gillespie syndrome caused by an ITPR1 variant. Conclusion: By employing droplet digital PCR, we detected paternal germline mosaicism in two intellectual disability syndromes. In both cases, the mosaicism level was higher in sperm than blood, indicating that analysis of blood alone may underestimate germline mosaicism. Therefore, sperm analysis can be clinically useful to establish the recurrence risk for parents and improve genetic counselling. [ABSTRACT FROM AUTHOR]

Abstract Background De novo variants are a common cause to rare intellectual disability syndromes, associated with low recurrence risk. However, when such variants occur pre‐zygotically in parental germ cells, the recurrence risk might be higher. Still, the recurrence risk estimates are mainly based on empirical data and the prevalence of germline mosaicism is often unknown. Methods To establish the prevalence of mosaicism in parents of children with intellectual disability syndromes caused by de novo variants, we performed droplet digital PCR on DNA extracted from blood (43 trios), and sperm (31 fathers). Results We detected low‐level mosaicism in sperm‐derived DNA but not in blood in the father of a child with Kleefstra syndrome caused by an EHMT1 variant. Additionally, we found a higher level of paternal mosaicism in sperm compared to blood in the father of a child with Gillespie syndrome caused by an ITPR1 variant. Conclusion By employing droplet digital PCR, we detected paternal germline mosaicism in two intellectual disability syndromes. In both cases, the mosaicism level was higher in sperm than blood, indicating that analysis of blood alone may underestimate germline mosaicism. Therefore, sperm analysis can be clinically useful to establish the recurrence risk for parents and improve genetic counselling.

BackgroundAlport syndrome is a hereditary glomerulopathy featured by haematuria, proteinuria, and progressive renal failure. X-linked Alport syndrome (XLAS) due to COL4A5 disease-causing variants is the most common form. In the case of XLAS resulting from 10–18% presumed de novo COL4A5 disease-causing variants, there are only a few studies for mosaicism in the probands or parents. Very low-level (A in COL4A5 (NM_033380) intron 28, whereas this disease-causing variant was not detected in genomic DNA extracted from peripheral blood leukocytes in the woman using Sanger sequencing. She had multiple normal urine test results, and continuous linear immunofluorescence staining of α2 (IV) and α5 (IV) chains of skin tissue. Sanger sequencing demonstrated that COL4A5 disease-causing variant c. 2245-1G>A was not detected in her genomic DNAs isolated from urine sediments, saliva, and hair roots. Using ddPCR, the wild-type and mutant-type (c.2245-1G>A) COL4A5 was identified in the female's genomic DNAs isolated from peripheral blood, saliva, and urine sediments. The mutant allelic fractions in these tissues were 0.26% (peripheral blood), 0.73% (saliva), and 1.39% (urine), respectively.ConclusionsGermline and very low-level somatic mosaicism for a COL4A5 splicing variant was detected in an asymptomatic female, which highlights that parental mosaicism should be excluded when a COL4A5 presumed de novo disease-causing variant is detected.

Introduction: Complex cortical dysplasia with other brain malformations-7 (a.k.a. polymicrogyria) caused by mutations in TUBB2B gene is a clinically heterogeneous condition. Case report: We report two siblings with polymicrogyria. Brain MRI showed polymicrogyria, small brainstem, thin corpus callosum and fused basal ganglia. Karyotypes and chromosomal microarray analysis were normal. By whole exome sequencing, there were a de novo variant of c.728C > T (p.P243L) in both siblings and a common single nucleotide polymorphism (SNP) (c.718C > T) in both siblings and the mother. Seminal DNA analysis obtained from father was normal. Conclusion: Maternal germline mosaicism was considered because the sequencing result of the father's sperm was normal, two siblings had the same disease, and both patients and mother had the same SNP. [ABSTRACT FROM AUTHOR]

Alexander disease is a leukodystrophy caused by heterozygous mutations of GFAP gene. Recurrence in siblings from healthy parents provides a confirmation to the transmission of variants through germinal mosaicism. With the use of DNA isolated from peripheral blood, next-generation sequencing (NGS) of GFAP locus was performed with deep coverage (≥500×) in 11 probands and their parents (trios) with probands heterozygous for apparently de novo GFAP mutations. Indeed, one parent had somatic mosaicism, estimated in the range of 8.9%–16%, for the mutant allele transmitted to the affected sibling. Parental germline mosaicism deserves attention, as it is critical in assessing the risk of recurrence in families with Alexander disease. [ABSTRACT FROM AUTHOR]

Résumé Contexte La mise en évidence d’une mosaïque germinale est. un événement rare mais probablement sous-estimé du fait de l’accès limité aux cellules germinales. Les variations génomiques caractéristiques de ce phénomène peuvent être des single nucleotide polymorphismes (SNPs), des copy number variations (CNVs) ou des aneuploïdies. Dans le cas des CNVs, les délétions sont plus fréquentes dans la lignée germinale paternelle tandis que les duplications sont plus fréquemment d’origine maternelle. Le risque de mosaïcisme germinal augmente avec l’âge paternel de part une augmentation du risque de SNPs associée à la division constante des cellules germinales pendant toute la vie d’un homme. Nous rapportons ici un cas de mosaïque germinale chez un donneur de spermatozoïdes ayant entraîné la survenue d’une grossesse pathologique. Résultats Les paillettes d’un même donneur de spermatozoïdes ont été attribuées à sept couples receveurs permettant l’obtention de quatre grossesses évolutives. Pour l’une d’entre elle, l’échographie du deuxième trimestre a permis d’identifier chez le fœtus des pieds bots associés à un retard de croissance intra utérin. L’analyse par hybridation génomique comparative (CGH)-array après amniocentèse a révélé une délétion de 4 MB dans la région 7q32.1q33. Les caryotypes sanguins et les analyses par CGH-array étaient normaux chez la mère et le donneur. Cependant les profils de microsatellites ont montré une origine paternelle du chromosome délété. Une analyse par fluorescent in situ hybridization (FISH) des spermatozoïdes du donneur a révélé la présence de la même délétion dans 12% des spermatozoïdes étudiés. Etant donné le risque de retard mental associé à des remaniements chromosomiques dans cette même région, le couple a préféré interrompre la grossesse. Une amniocentèse a été réalisée pour les autres grossesse en cours et n’a retrouvé aucune anomalie. Conclusions Plusieurs cas de mosaïques germinales ont été rapportés mais leur fréquence réelle reste probablement sous-estimée. En effet, un mosaïcisme germinal ne peut être détecté par les techniques de cytogénétique conventionnelle sur sang. Ce cas illustre la nécessité d’un suivi en temps réel des grossesses obtenues par don de spermatozoïdes étant donné que la survenue d’une grossesse pathologique peut avoir un retentissement sur les autres grossesses issues du même donneur.

Abstract Background Monosomy 1p36 is the most common terminal deletion syndrome with an autosomal dominant pattern of inheritance. This syndrome is defined by an extremely wide spectrum of characteristics; however, developmental delay and intellectual disability of various degree are present in all patients and about the 90% of patients have a severe intellectual disability. Dental agenesis or other dental anomalies have not been described in previous reports. Case presentation We report the case of two little sisters born from healthy and non-consanguineous parents, presenting with dental anomalies and one of them with epilepsy, dilated cardiomyopathy with left-ventricular non-compaction, strabismus, history of poor growth, hypotonia and mild language delay. Patients were evaluated in several departments (genetic, child neuropsychiatric, cardiology, odontostomatology, ophthalmology, otorhinolaryngology) of Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy. They underwent investigations such as electrocardiogram, echocardiogram, dental orthopantomography X-Ray and Computed Tomography, electroencephalograms, abdomen ultrasound, blood tests, IQ tests, genetic analysis. They both have an Intelligence Quotient greater than 70 and a negative neurologic exam. Each sister carries the same 1p36 deletion of about 2.3 Mb. Genetic analysis of the parents’ blood samples (Single Nucleotide Polymorphism- array, karyotype and Fluorescent In Situ Hybridization) did not reveal any deletion, translocation or inversion and confirmed the paternity. A third sib of the probands does not carry the 1p36 deletion or other quantitative alterations. Conclusion This report describes a new trait linked to monosomy 1p36, namely a mild intellectual outcome associated with significant dental anomalies. Our finding suggests that 1p36 deletion syndrome may present with a mild cognitive impairment or even with a normal intellectual development: this is very important for the genetic counselling, especially in a prenatal setting. Moreover, we report the third study with recurrent 1p36 deletion syndrome in two siblings, likely due to germline mosaicism. Finally, we believe that the dental anomalies should be investigated in 1p36 deletion syndrome and that the spectrum of the condition could be broader than we assume.

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are the most common inherited neuromuscular diseases. Following the identification of a pathogenic causative variant in the DMD gene of a proband, potential carriers can be informed of their risk of having offspring with the disease. Germline mosaicism is a variant that is confined to the gonads that can be transmitted to offspring and is usually reported when a non-carrier of a DMD pathogenic variant has two or more offspring carrying the variant in question. On average, one third of cases are the result of a de novo variant, and as DMD and BMD are prone to germline mosaicism, its inclusion in genetic counseling is mandatory. In this retrospective cohort study, we presented clinical data from an unpublished DMD/BMD cohort of 332 families with incidence of germline mosaicism in families with de novo transmission of 8.1%. This is also the first systematic literature review searching PubMed to provide an accurate assessment of the current literature on germline mosaicism in DMD and BMD, including 17 case reports and 20 original studies. The incidence of documented germline mosaicism in de novo event families ranged from 6.0 to 40%, with a mean of 8.3%. The estimated recurrence risk for mothers of a patient with a proven de novo causal variant ranged from 4.3 to 11%, with a mean of 5.8% for a male fetus. By providing an up-to-date and comprehensive overview of the literature, this review aims to improve our understanding of germline mosaicism in DMD and to promote the development of effective strategies and reliable data for occurrence risk assessment in genetic counseling of de novo event families., (© 2024 The Author(s). Journal of Genetic Counseling published by Wiley Periodicals LLC on behalf of National Society of Genetic Counselors.)

Background: Nicolaides–Baraitser syndrome (NCBRS) is a severe neurodevelopmental disorder with multiple abnormalities. To date, all pathogenic variants in SMARCA2 causing NCBRS are de novo and most are missense variants located in the ATPase domain of SMARCA2 protein. Methods: In this study, a familial trio whole‐exome sequencing was performed on the proband presenting with intellectual disability, early‐onset epilepsy, and autistic features. A novel missense variant c.553C>G (p.Gln185Glu) in SMARCA2 was identified, which is located in the QLQ domain. The same variant was subsequently also found in the mother's ongoing pregnancy. Samples from accessible tissues such as saliva and sperm other than blood were collected from the parents, and the detection of the target variant was performed by amplicon‐based deep sequencing. Results: Low‐level mosaicism of the target variant c.553C>G (p.Gln185Glu) was detected in the father's sperm with allele fraction of 2.8% by amplicon‐based deep sequencing, which was not detected in either parents' blood or saliva specimens. Heterozygosity of this variant was confirmed in the proband. Conclusion: This is the first report of paternal germline mosaicism for a SMARCA2 disease‐causing variant. In addition, the missense variant c.553C>G (p.Gln185Glu) in the QLQ domain causes mainly neurological and developmental phenotypes with unremarkable characteristic facial features and limb abnormalities. Our findings expand the phenotypic spectrum and mode of genetic transmission associated with the SMARCA2 variants. [ABSTRACT FROM AUTHOR]

Abstract Background Nicolaides–Baraitser syndrome (NCBRS) is a severe neurodevelopmental disorder with multiple abnormalities. To date, all pathogenic variants in SMARCA2 causing NCBRS are de novo and most are missense variants located in the ATPase domain of SMARCA2 protein. Methods In this study, a familial trio whole‐exome sequencing was performed on the proband presenting with intellectual disability, early‐onset epilepsy, and autistic features. A novel missense variant c.553C>G (p.Gln185Glu) in SMARCA2 was identified, which is located in the QLQ domain. The same variant was subsequently also found in the mother's ongoing pregnancy. Samples from accessible tissues such as saliva and sperm other than blood were collected from the parents, and the detection of the target variant was performed by amplicon‐based deep sequencing. Results Low‐level mosaicism of the target variant c.553C>G (p.Gln185Glu) was detected in the father's sperm with allele fraction of 2.8% by amplicon‐based deep sequencing, which was not detected in either parents’ blood or saliva specimens. Heterozygosity of this variant was confirmed in the proband. Conclusion This is the first report of paternal germline mosaicism for a SMARCA2 disease‐causing variant. In addition, the missense variant c.553C>G (p.Gln185Glu) in the QLQ domain causes mainly neurological and developmental phenotypes with unremarkable characteristic facial features and limb abnormalities. Our findings expand the phenotypic spectrum and mode of genetic transmission associated with the SMARCA2 variants.

Germline mosaicism should be suspected when the same de novo mutations are identified in a second pregnancy with asymptomatic parents. Our study aims to find a feasible approach to reveal the existence of germline mosaicism. Multiplex Ligation-dependent Probe Amplification was performed on a Duchenne muscular dystrophy affected pedigree to detect deletion mutations. Then gap-polymerase chain reaction was performed to amplify the breakpoints junction sequence. Droplet digital polymerase chain reaction was utilized to identify the mutation frequencies in healthy parents. The same deletion in the exon 51 of the dystrophin gene, which was 50,035 bp in size, was detected in the proband and the fetus but not in their parents. Droplet digital polymerase chain reaction analysis of peripheral blood samples revealed mutant alleles of 3.53% in maternal blood cells. We here report a case of maternal low-level mosaicism confirmed by droplet digital polymerase chain reaction in peripheral blood samples, which reveals the existence of germline mosaicism. Gap-polymerase chain reaction combined with droplet digital polymerase chain reaction provide insights into the detection of germline mosaicism.

Germline mosaicism should be suspected when the same de novo mutations are identified in a second pregnancy with asymptomatic parents. Our study aims to find a feasible approach to reveal the existence of germline mosaicism. Multiplex Ligation-dependent Probe Amplification was performed on a Duchenne muscular dystrophy affected pedigree to detect deletion mutations. Then gap-polymerase chain reaction was performed to amplify the breakpoints junction sequence. Droplet digital polymerase chain reaction was utilized to identify the mutation frequencies in healthy parents. The same deletion in the exon 51 of the dystrophin gene, which was 50,035 bp in size, was detected in the proband and the fetus but not in their parents. Droplet digital polymerase chain reaction analysis of peripheral blood samples revealed mutant alleles of 3.53% in maternal blood cells. We here report a case of maternal low-level mosaicism confirmed by droplet digital polymerase chain reaction in peripheral blood samples, which reveals the existence of germline mosaicism. Gap-polymerase chain reaction combined with droplet digital polymerase chain reaction provide insights into the detection of germline mosaicism. [ABSTRACT FROM AUTHOR]

Familial Rubinstein-Taybi syndrome (RSTS) with recurrent RSTS siblings and apparently unaffected parents is rare; such cases might result from parental somatic and/or germline mosaicism. Parental low-level (T (p.Gln1079*) in CREBBP in the siblings via trio whole-exome sequencing. High-depth next-generation sequencing (NGS) for the parents revealed a low-level (T (p.Gln1079*) non-sense variant did not trigger nonsense-mediated mRNA decay to reduce CREBBP mRNA levels. Transcriptome analysis revealed 151 downregulated mRNAs and 132 upregulated mRNAs between the patients and normal individuals. This study emphasizes that high-depth NGS using multiple specimens might be applied for a family with an affected sibling caused by an apparent CREBBP DNV to identify potential low-level parental mosaicism and provide an assessment of recurrence risk.

Familial Rubinstein-Taybi syndrome (RSTS) with recurrent RSTS siblings and apparently unaffected parents is rare; such cases might result from parental somatic and/or germline mosaicism. Parental low-level (<10%) germline mosaicism in the CREBBP-associated RSTS family has not been reported. Here, we present our studies of a Chinese family with two RSTS siblings and apparently unaffected parents. We detected the apparent de novo variant (DNV) c.3235C>T (p.Gln1079*) in CREBBP in the siblings via trio whole-exome sequencing. High-depth next-generation sequencing (NGS) for the parents revealed a low-level (<10%) mosaic variant in both the peripheral blood (3.64%) and buccal mucosa (1.94%) of the unaffected mother, indicating maternal somatic and germline mosaicism. Peripheral blood RNA-sequencing analysis for the patients and normal individuals indicated that the c.3235C>T (p.Gln1079*) non-sense variant did not trigger nonsense-mediated mRNA decay to reduce CREBBP mRNA levels. Transcriptome analysis revealed 151 downregulated mRNAs and 132 upregulated mRNAs between the patients and normal individuals. This study emphasizes that high-depth NGS using multiple specimens might be applied for a family with an affected sibling caused by an apparent CREBBP DNV to identify potential low-level parental mosaicism and provide an assessment of recurrence risk. [ABSTRACT FROM AUTHOR]

Treacher Collins syndrome (TCS) is a rare congenital craniofacial disorder, typically inherited as an autosomal dominant condition. Here, we report on a family in which germline mosaicism for TCS was likely present. The proband was diagnosed with TCS based on the typical clinical features and a pathogenic variant TCOF1 (c.4369&#95;4373delAAGAA, p.K1457Efs*12). The mutation was not detected in his parents' peripheral blood DNA samples, suggesting a de novo mutation had occurred in the proband. However, a year later, the proband's mother became pregnant, and the amniotic fluid puncture revealed that the fetus carried the same mutation as the proband. Prenatal ultrasound also indicated a maxillofacial dysplasia with unilateral microtia. The mother then disclosed a previous birth history in which a baby had died of respiratory distress shortly after birth, displaying a TCS-like phenotype. Around the same time, the proband's father was diagnosed with mild bilateral conductive hearing loss. Based on array data, we concluded that the father may have had germline mosaicism for TCOF1 mutation. Our findings highlight the importance of considering germline mosaicism in sporadic de novo TCOF1 mutations when providing genetic consulting, and prenatal diagnosis is important when the proband's parents become pregnant again., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

KIF1A is a molecular motor for membrane‐bound cargo important to the development and survival of sensory neurons. KIF1A dysfunction has been associated with several Mendelian disorders with a spectrum of overlapping phenotypes, ranging from spastic paraplegia to intellectual disability. We present a novel pathogenic in‐frame deletion in the KIF1A molecular motor domain inherited by two affected siblings from an unaffected mother with apparent germline mosaicism. We identified eight additional cases with heterozygous, pathogenic KIF1A variants ascertained from a local data lake. Our data provide evidence for the expansion of KIF1A‐associated phenotypes to include hip subluxation and dystonia as well as phenotypes observed in only a single case: gelastic cataplexy, coxa valga, and double collecting system. We review the literature and suggest that KIF1A dysfunction is better understood as a single neuromuscular disorder with variable involvement of other organ systems than a set of discrete disorders converging at a single locus. [ABSTRACT FROM AUTHOR]

Abstract Background Prezygotic de novo mutations may be inherited from parents with germline mosaicism and are often overlooked when the resulting phenotype affects only one child. We aimed to identify paternal germline mosaicism in an index family and provide a strategy to determine germline mosaicism.‘ Methods Whole‐exome sequencing was performed on an Alport syndrome‐affected child. Variants were validated using Sanger sequencing in the pedigree analysis. An apparent de novo mutation was tested by next‐generation sequencing (NGS) following chromosome microdissection of the mutant region (MicroSeq) to clarify its homologous chromosome source. Mosaic mutation in sperm samples was detected using targeted next‐generation sequencing (TNGS). Self‐prepared mosaic DNA samples of the 3% and 0.1% mutant fractions were used to evaluate the TNGS detection sensitivity. Results Two novel heterozygous variants, maternally inherited c.1322delT (p.Ile441Thrfs*17) and the de novo mutation c.2939T>A (p.Leu980Ter), in the COL4A3 gene were discovered in the propositus. MicroSeq identified c.2939T>A in the paternal chromosome, which was in trans with c.1322delT. The frequency of c.2937A was 2.65% in the father's sperm sample. We also showed that a 500X depth coverage may detect a mosaic mutation with an allele frequency as low as 2%–3% using TNGS. Conclusion MicroSeq is a valuable tool to identify the allele source of de novo mutations in a single patient. TNGS can be used to assess the mosaic ratios of known sites. We provided a systematic algorithm to detect germinal mosaicism in a single patient. This algorithm may have implications for genetic and reproductive counseling on germline mosaicism.

Background: Prezygotic de novo mutations may be inherited from parents with germline mosaicism and are often overlooked when the resulting phenotype affects only one child. We aimed to identify paternal germline mosaicism in an index family and provide a strategy to determine germline mosaicism.' Methods: Whole‐exome sequencing was performed on an Alport syndrome‐affected child. Variants were validated using Sanger sequencing in the pedigree analysis. An apparent de novo mutation was tested by next‐generation sequencing (NGS) following chromosome microdissection of the mutant region (MicroSeq) to clarify its homologous chromosome source. Mosaic mutation in sperm samples was detected using targeted next‐generation sequencing (TNGS). Self‐prepared mosaic DNA samples of the 3% and 0.1% mutant fractions were used to evaluate the TNGS detection sensitivity. Results: Two novel heterozygous variants, maternally inherited c.1322delT (p.Ile441Thrfs*17) and the de novo mutation c.2939T>A (p.Leu980Ter), in the COL4A3 gene were discovered in the propositus. MicroSeq identified c.2939T>A in the paternal chromosome, which was in trans with c.1322delT. The frequency of c.2937A was 2.65% in the father's sperm sample. We also showed that a 500X depth coverage may detect a mosaic mutation with an allele frequency as low as 2%–3% using TNGS. Conclusion: MicroSeq is a valuable tool to identify the allele source of de novo mutations in a single patient. TNGS can be used to assess the mosaic ratios of known sites. We provided a systematic algorithm to detect germinal mosaicism in a single patient. This algorithm may have implications for genetic and reproductive counseling on germline mosaicism. [ABSTRACT FROM AUTHOR]

Background: Monosomy 1p36 is the most common terminal deletion syndrome with an autosomal dominant pattern of inheritance. This syndrome is defined by an extremely wide spectrum of characteristics; however, developmental delay and intellectual disability of various degree are present in all patients and about the 90% of patients have a severe intellectual disability. Dental agenesis or other dental anomalies have not been described in previous reports.Case Presentation: We report the case of two little sisters born from healthy and non-consanguineous parents, presenting with dental anomalies and one of them with epilepsy, dilated cardiomyopathy with left-ventricular non-compaction, strabismus, history of poor growth, hypotonia and mild language delay. Patients were evaluated in several departments (genetic, child neuropsychiatric, cardiology, odontostomatology, ophthalmology, otorhinolaryngology) of Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy. They underwent investigations such as electrocardiogram, echocardiogram, dental orthopantomography X-Ray and Computed Tomography, electroencephalograms, abdomen ultrasound, blood tests, IQ tests, genetic analysis. They both have an Intelligence Quotient greater than 70 and a negative neurologic exam. Each sister carries the same 1p36 deletion of about 2.3 Mb. Genetic analysis of the parents' blood samples (Single Nucleotide Polymorphism- array, karyotype and Fluorescent In Situ Hybridization) did not reveal any deletion, translocation or inversion and confirmed the paternity. A third sib of the probands does not carry the 1p36 deletion or other quantitative alterations.Conclusion: This report describes a new trait linked to monosomy 1p36, namely a mild intellectual outcome associated with significant dental anomalies. Our finding suggests that 1p36 deletion syndrome may present with a mild cognitive impairment or even with a normal intellectual development: this is very important for the genetic counselling, especially in a prenatal setting. Moreover, we report the third study with recurrent 1p36 deletion syndrome in two siblings, likely due to germline mosaicism. Finally, we believe that the dental anomalies should be investigated in 1p36 deletion syndrome and that the spectrum of the condition could be broader than we assume. [ABSTRACT FROM AUTHOR]

Approximately 70% of patients with haemophilia exhibit a clear inheritance pattern, while for the remaining 30%, patients are the first to be diagnosed in their family and are considered sporadic cases. In such a setting, the determination of carrier status and the risk estimation of disease transmission to another child are major challenges for genetic counselling. Large studies have suggested that genetic testing reveals 70% of sporadic patients' mothers are carriers. In the remaining 30%, in some apparently non‐carrier mothers, the pathogenic variant can be detected as low somatic and gonosomal mosaicism. The significance of mosaic pathogenic variants has thus far been underestimated, since conventional Sanger sequencing and other technology are not sufficiently sensitive. The study of various tissue samples and recent extra‐sensitive molecular methods have now made it easier to detect both single‐nucleotide variants (SNVs) and copy‐number variants (CNVs), at a mosaic level in parents, and to predict the probability of disease recurrence. This review seeks to examine various kinds of mosaicism in haemophilia, including the mechanisms by which they arise and the risk of passing these variants on to the next generation. In addition, we focus on the selection of cell tissues and methods to detect these mosaic variants in the haemophilia setting. Taking into account the high rate of mosaicism in mothers of sporadic cases, we propose a diagnostic flow chart that could facilitate better evaluation of the risk of transmitting haemophilia in genetic and prenatal counselling. [ABSTRACT FROM AUTHOR]

The COL2A1 gene encodes the alpha‐1 chain of procollagen type 2. Pathogenic variants in the COL2A1 gene are associated with several different types of skeletal dysplasia collectively known as type 2 collagenopathies. Type 2 collagenopathies have an autosomal dominant inheritance. Some germline or somatogonadal mosaicism cases have been reported. We investigated whether somatogonadal mosaicism occurred in a family with two children suspected of type 2 collagenopathies or related diseases. First, we detected a pathogenic variant in the COL2A1 gene in the two affected children by whole exome sequencing (WES). Next, we performed targeted deep sequencing to their parents without the variant by WES. A low level of COL2A1 mosaicism was revealed in the mother's tissues. We concluded that the mother had somatogonadal mosaicism with the COL2A1 mutation arose in the epiblast, and that the intrafamilial recurrence rate of the disease by the somatogonadal mosaicism was higher than by the germline mosaicism. This report suggests that parental low‐level mosaicism should be evaluated in those parents with children carrying de novo germline mutations and the targeted deep sequencing is useful to detect them. [ABSTRACT FROM AUTHOR]

The present study aimed to determine the genetic status of manifesting carriers (MCs) of Duchenne muscular dystrophy (DMD)/Becker muscular dystrophy (BMD) and asymptomatic carriers with a family history of DMD/BMD, and identify potential simple and reliable methods for screening dystrophinopathy carriers. Clinical data from probable carriers and MCs were collected and analyzed. MCs underwent multiplex ligation-dependent probe amplification (MLPA) for dystrophin gene exons combined with muscle disease panel test based on a next-generation sequencing (NGS) platform. In addition, the status of probable carriers was determined by MLPA or Sanger sequencing, according to the mutations of probands. A total of 154 female were enrolled, among which 78 cases were found to be carriers, including 4 MCs and 74 asymptomatic female carriers. The 4 MCs exhibited duplication mutations. Among the 74 asymptomatic carriers, 41.89% harbored deletion mutations, including 2 cases with suspected germline mosaicism and no mutation in the dystrophin gene, while 44.59% harbored point mutations in exons and only 10 cases (13.51%) carried duplication mutations. The area under the receiver operating characteristic (ROC) curve of creatine kinase (CK) was 0.822, with a sensitivity of 65.38% and specificity of 92.1%. In addition, DMD was positively correlated with the CK, alanine transaminase and aspartate transaminase levels of the carriers. MLPA for exons of the dystrophin gene, along with NGS and Sanger sequencing, was effective for the diagnosis of MCs and for determining the status of probable carriers. The ROC curve analysis also demonstrated that CK level was an excellent predictor for distinguishing DMD/BMD carriers. [ABSTRACT FROM AUTHOR]

Abstract Jacobsen syndrome refers to a congenital anomaly caused by deletion at 11q23.3-qter. We here describe two siblings with the same 11q23.3-qter deletion. Both parents were healthy with a normal karyotype. Cytogenetic microarray analysis revealed no mosaicism in either parent but the mother showed uniparental disomy encompassing the deleted region found in the two siblings. The pattern of X chromosome inactivation was almost completely skewed in the mother. These data suggested that the mother was a carrier of the 11q23.3-qter deletion but that this had been rescued by disomy formation during early embryogenesis except for her germinal cells. [ABSTRACT FROM AUTHOR]