Human Genome Variation最新文献

Alport syndrome is a hereditary disorder characterized by renal impairment, hearing loss, and ocular symptoms and is caused by COL4A3, COL4A4, and COL4A5 mutations. Here, we report the case of 3-year-old boy with isolated hematuria detected in routine preventative urinary screening conducted in 3-year-old children. He carried a novel variant, NM_033380.3:c. 1032 + 1 G > A, which caused a splicing abnormality in COL4A5. He was diagnosed with X-linked Alport syndrome.

Dystonia (DYT) is a heterogeneous neurological disorder, and there are many types of DYT depending on the responsible genes. DYT11 is an autosomal dominant DYT caused by functional variants in the SGCE gene. We examined a Japanese patient with myoclonic dystonia. By using exome analysis, we identified a rare variant in the SGCE gene, NM_003919.3: c.304C > T [Arg102*], in this patient. Therefore, this patient has been molecularly diagnosed with DYT11. By Sanger sequencing, we confirmed that this variant was paternally inherited in this patient. By allele-specific PCR, we confirmed that the maternally inherited normal allele of SGCE was silenced, and only the paternally inherited variant allele was expressed in this patient. Despite the pathogenicity, identical variants have been recurrently reported in eight independent families from different ethnicities, suggesting recurrent mutations at this mutational hotspot in SGCE.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a hereditary cardiomyopathy that results in fatal arrhythmias and heart failure. Herein, we report a Japanese patient with ARVC whose parents were blood relatives. Genetic testing identified a homozygous rare variant, c.1592T > G (p.Phe531Cys), of DSG2 that is presumed to be a founder variant among East Asians. Genetic counseling sessions with precise risk assessment and appropriate follow-up programs were provided to the patient and family members.

A heterozygous mutation in GRID2 that causes SCAR18 was first reported in an Algerian family with autosomal dominant cerebellar ataxia (ADCA). We identified the second ADCA family with a heterozygous GRID2 mutation. The Algerian family had cognitive impairment and hearing loss associated with cerebellar ataxia. However, the Japanese family presented here showed pure cerebellar ataxia. Therefore, we should also screen for the GRID2 mutation in ADCA families with pure cerebellar ataxia.

Coffin-Siris syndrome (CSS) is a congenital disorder that is characterized by an absent/hypoplastic fifth distal phalanx, psychomotor developmental delay, and coarse facial features. One of the causative genes, ARID1B (AT-rich interactive domain-containing protein 1B), encodes components of the BAF chromatin remodeling complexes. Here, we report a case of a 3-year 8-month-old male with a novel nonsense variant (NM_001374820.1:c.4282C > T, p.(Gln1428*)) in the ARID1B gene, which was identified with whole-exome sequencing. He showed clinical symptoms of cleft soft palate, distinctive facial features (flat nasal bridge, thick eyebrows, and long eyelashes), right cryptorchidism, and hypertrichosis that partially overlapped with CSS. One of the most characteristic features of CSS is absent/hypoplastic fifth distal phalanx. He showed no obvious clinical finding in the lengths of his fingers or in the formation of his fingernails. However, radiographic analyses of the metacarpophalangeal bones revealed shortening of all the distal phalanges and fifth middle phalanges, suggesting brachydactyly. We performed mRNA analyses and revealed that both nonsense-mediated decay and nonsense-associated altered splicing were simultaneously caused by the c.4282C > T nonsense variant. The proband's clinical manifestations fit the previously reported criteria of disease for CSS or intellectual disability with ARID1B variant. Altogether, we suggest that c.4282C > T is a pathogenic variant that causes this clinical phenotype.

Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) is a rare renal cancer. A 75-year-old Japanese female presented with gross hematuria. Computed tomography revealed two tumors in the left kidney, which were resected. Immunohistochemistry indicated negative staining for the B subunit of SDH (SDHB) in the resected specimen, leading to a final diagnosis of SDHB-deficient RCC. Genetic testing for SDHB showed a RCC germline variant in exon 6 (NM_003000.3:c.642 G > C) that was previously reported but associated with a novel phenotype (i.e., RCC). Twenty-six years prior, her daughter, who was 25 years old at the time, had undergone radical nephrectomy for a pathologic diagnosis of renal oncocytoma of the right kidney; SDHB immunostaining of her daughter's tumor was also negative retrospectively. We confirmed that her daughter carried the germline variant in SDHB exon 6, similar to the patient. The patient had no evidence of disease progression at 15 months after surgery.

A 2-day-old neonate presented with seizures, multiple intracranial hemorrhages, and bilateral congenital cataracts. Targeted next-generation sequencing of the collagen type IV alpha 1 chain (COL4A1) gene revealed a heterozygous de novo missense variant (NM_001845.6:c.2291G>A/p.Gly764Asp). This missense variant adds to the compendium of COL4A1 variants and is associated with a COL4A1-related disorder.

Here, we report a Japanese patient with Simpson-Golabi-Behmel syndrome involving a de novo 240-kb deletion including a part of GPC3. The patient showed pre- and postnatal macrosomia associated with coarse face, macrocephaly, supernumerary nipples, and cryptorchidism and characteristically presented with precocious puberty, mostly evaluated as advanced pubertal age of 15 years at the chronological age of 11.5 years.

We describe a case of Cockayne syndrome without photosensitivity in a Vietnamese family. This lack of photosensitivity prevented the establishment of a confirmed medical clinical diagnosis for 16 years. Whole-exome sequencing (WES) identified a novel missense variant combined with a known nonsense variant in the ERCC6 gene, NM_000124.4: c.[2839C>T;2936A>G], p.[R947*;K979R]. This case emphasizes the importance of WES in investigating the etiology of a disease when patients do not present the complete clinical phenotypes of Cockayne syndrome.