A novel FN1 variant associated with familial hematuria: TBMN?

An SCN1A gene missense variant in a Chinese Tujia ethnic family with genetic epilepsy with febrile seizures plus

Genetic epilepsy with febrile seizures plus (GEFSP) is a familial epileptic syndrome that is genetically heterogeneous and inherited in an autosomal dominant form in most cases. To date, at least seven genes have been reported to associate with GEFSP. This study aimed to identify the disease-causing variant in a Chinese Tujia ethnic family with GEFSP by using whole exome sequencing, Sanger sequencing, and in silico prediction. A heterozygous missense variant c.5725A>G (p.T1909A) was identified in the sodium voltage-gated channel alpha subunit 1 gene (SCN1A) coding region. The variant co-segregated with the GEFSP phenotype in this family, and it was predicted as disease-causing by multiple in silico programs, which was proposed as the genetic cause of GEFSP, further genetically diagnosed as GEFSP2. These findings expand the genetic and phenotypic spectrum of GEFSP and should contribute to genetic diagnoses, personalized therapies, and prognoses.

Identification of a de novo TSC2 variant in a Han-Chinese family with tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder with a variety of clinical findings. Variants in the TSC complex subunit 1 gene (TSC1) or the TSC complex subunit 2 gene (TSC2) are responsible for TSC.

METHODS

Physical examinations, computed tomography scans, and light microscopy analyses were performed on the TSC patient from a Han-Chinese pedigree. Whole-exome sequencing combined with Sanger sequencing were performed on the family members.

RESULTS

The TSC patient showed typical clinical features, including facial angiofibromas, gingival fibromas, a shagreen patch, hypomelanotic macules, ungual fibromas, subependymal nodules, multiple pulmonary cysts, and renal hamartomas. A de novo heterozygous c.5146delG (p.Ala1716Profs*110) variant in the TSC2 gene was identified in the TSC patient of the Han-Chinese family. To our knowledge, this is the first report of the TSC2 c.5146delG variant associated with TSC.

CONCLUSION

The study expanding the disease-causing variant spectrum, suggests that whole-exome sequencing combined with Sanger sequencing may be a method for TSC diagnosis and differential diagnosis, and may facilitate the development of genetic counseling and targeted gene therapy for this disease.

A Disease-Causing FRMD7 Variant in a Chinese Family with Infantile Nystagmus

In this report, we described a large Han-Chinese family which presents with various phenotypes from unaffected to manifested nystagmus in females. Infantile nystagmus (IN) is characterized by bilateral, involuntary, and periodic eyeball oscillation, occurring at birth or within the first 6 months. The most common inheritance pattern of IN is an X-linked form with incomplete penetrance among females, and the FERM domain containing 7 gene (FRMD7) is a main disease-causing gene. A combination of exome sequencing and Sanger sequencing, as well as detailed clinical examinations were performed on the Chinese IN family. An FRMD7 c.47T>C (p.Phe16Ser) variant was proposed as the disease-causing variant. Incomplete penetrance was found in females with the FRMD7 c.47T>C variant, and hemizygous male affected subjects presented more severe manifestations compared to heterozygous female affected subjects. These findings could enhance genetic counseling and antenatal diagnosis of IN.

Hemizygous F8 p.G201E mutation identified in a Chinese family with haemophilia A

BACKGROUND

Haemophilia A (HA), inherited via an X-linked recessive pattern, is the most common severe lifelong bleeding disorder caused by mutations in the coagulation factor VIII gene (F8). It has significant socio-economic effects due to its long course of disease and high cost of care. These impacts argue for a more accurate genetic diagnosis in an increasingly complex clinical environment.

METHODS

A three-generation Han-Chinese family with mild HA was recruited in the study. Exome sequencing was performed in the index case to detect potential disease-causing mutations, and Sanger sequencing was applied to verify the mutation in the family.

RESULTS

A hemizygous c.602G > A variant in the F8 gene, leading to a single amino acid substitution at codon 201 from glycine to glutamic acid (p.G201E) within the factor VIII (FVIII) A1 domain, was identified in the HA family. This mutation detected in the proband was found in his affected sibling, while it was absent in the unaffected family member and the two hundred ethnically-matched controls. The mutation affects an evolutionary conserved residue, which may impact the tertiary structure of FVIII.

CONCLUSION

The study findings should provide for more dependable and precise genetic counseling which may assist in perfecting family management.

Identification of a Novel Mutation in the ABCA4 Gene in a Chinese Family with Retinitis Pigmentosa Using Exome Sequencing

Retinitis pigmentosa (RP) is a group of hereditary, degenerative retinal disorders characterized by progressive retinal dysfunction, outer retina cell loss, and retinal tissue atrophy. It eventually leads to tunnel vision and legal or total blindness. Here, we aimed to reveal the causal gene and mutation contributing to the development of autosomal recessive RP (arRP) in a consanguineous family. A novel homozygous mutation, c.4845delT (p.K1616Rfs*46), in the ATP-binding cassette subfamily A member 4 gene (ABCA4) was identified. It may reduce ABCA4 protein activity, leading to progressive degeneration of both rod and cone photoreceptors. The study extends the arRP genotypic spectrum and confirms a genotype–phenotype relationship. The present study may also disclose some new clues for RP genetic causes and pathogenesis, as well as clinical and genetic diagnosis. The research findings may contribute to improvement in clinical care, therapy, genetic screening, and counseling.

Genetic analysis of the RIC3 gene in Han Chinese patients with Parkinson's disease

Parkinson's disease (PD) is the second-most common etiologically complex neurodegenerative disease. Genetic abnormalities are thought to play an important role in the development of PD. Recently, mutations in the resistance to inhibitors of cholinesterase 3 gene (RIC3) have been reported to cause autosomal-dominant PD in Indian population. To determine whether RIC3 gene coding variant(s) are associated with PD in Han Chinese population, the RIC3 gene coding region in 218 mainland Han Chinese patients with PD and the identified variants in 242 normal controls were examined using direct sequencing analysis. Four known single nucleotide variants (c.354C>A, p.L118L, rs10839976; c.389G>A, p.C130Y, rs55990541; c.403C>T, p.P135S, rs73411617; and c.1054G>A, p.D352N, rs11826236) were identified in the RIC3 gene coding region. No significant differences were observed in either genotypic or allelic distributions between the PD patients and the normal controls (all P>0.05) for these four variants. Haplotype analysis showed that the presence of haplotype A-G-C-G (rs10839976-rs55990541-rs73411617-rs11826236) was associated with a 0.764-fold decreased risk (P=0.049, OR=0.764, 95% CI=0.585-0.999) for PD, whereas the presence of haplotype C-A-C-A was associated with a 2.143-fold increased risk (P=0.039, OR=2.143, 95% CI=1.023-4.488) for PD. The findings indicate that four variants: rs10839976, rs55990541, rs73411617 and rs11826236 in the RIC3 gene coding region may play little or no role in the development of PD. Two RIC3 gene haplotypes of four variants: A-G-C-G, and C-A-C-A might relate to either protection against or increased susceptibility to PD in the Han Chinese population, respectively.

Novel CLCN7 mutation identified in a Han Chinese family with autosomal dominant osteopetrosis-2

Osteopetrosis is a heritable bone condition featuring increased bone density due to defective osteoclastic bone resorption. Exome sequencing and Sanger sequencing were conducted in Han Chinese family members, some of whom had typical osteopetrosis, and a novel missense variant c.2350A>T (p.R784W) in the chloride channel 7 gene (CLCN7) was identified. This variant cosegregated with the disorder in the family but was not observed in 800 controls. The data indicate that exome sequencing is a powerful and effective molecular diagnostic tool for detecting mutations in osteopetrosis, which is a genetically and clinically heterogeneous disorder. This discovery broadens the CLCN7 gene mutation spectrum and has important implications for clinical therapeutic regimen decisions, prognosis evaluations, and antenatal diagnoses.