Journal of Human Genetics最新文献

Biallelic loss of function variants in ESAM (endothelial cell adhesion molecule) have recently been reported in 14 individuals (9 families) presenting with prenatal intracranial hemorrhage. Here, we describe four patients from two unrelated families in whom three of them presented with variable onset encephalopathy and seizures while one only displayed profound delay without seizures. Brain MRI showed variable onset intracranial hemorrhage that evolved to hydrocephalus in 3 patients, whereas hemosiderin deposits, white matter volume loss, and porencephalic cysts were noted in one patient. Unlike the majority of described cases, the youngest brother of the first family did not show microcephaly and failure to thrive. Exome sequencing identified two novel homozygous ESAM variants. A splice variant (c.731-2A>G) was identified in one family which was confirmed by investigating the patient's mRNA to result in exon skipping and early protein truncation. In addition, a missense variant (c.561G>C; p.Trp187Cys) was identified in the other family, which is the first disease causing missense variant to be described in patients with ESAM deficient phenotype. In addition, a maternally inherited pathogenic MC4R variant (c.811T>C; p.Cys271 Arg) was also identified in the youngest brother of the first family. Variants in the MC4R gene are associated with a non-syndromic form of obesity that could explain the unusual macrocephaly and obesity. Our work establishes ESAM as a tight junction gene that can present with variable neuroradiological and clinical phenotypes when mutated. Moreover, it refines the phenotype of this ultrarare syndrome and extends the number and type of variants described to date.

FBXW7 (F-box and WD-repeat domain-containing 7) is a tumor suppressor gene, and its germline variants have been causally linked to Wilms tumors. Furthermore, germline variants of FBXW7 have also been implicated in a neurodevelopmental syndrome. However, little is known regarding the occurrence of Wilms tumor in patients with FBXW7-related neurodevelopmental syndrome. We identified a novel constitutional pathogenic variant of FBXW7 in a patient with intellectual disability, who also developed Wilms tumor. The variant was derived from his apparently normal mother, and was also detected in his sister who exhibited developmental delay. Furthermore, we detected a somatic nonsense variant on the paternal allele of FBXW7 in the tumor DNA. These results suggest that the development of Wilms tumor along with FBXW7-related neurodevelopmental syndrome follows the two-hit model, which needs to be validated to establish appropriate follow-up management and tumor surveillance.

CEP55 encodes centrosomal protein 55 kDa, which plays a crucial role in mitosis, particularly cytokinesis. Biallelic CEP55 variants cause MARCH syndrome (multinucleated neurons, anhydramnios, renal dysplasia, cerebellar hypoplasia and hydranencephaly). Here, we describe a Japanese family with two affected siblings harboring novel compound heterozygous CEP55 variants, NM_001127182: c.[1357 C > T];[1358 G > A] p.[(Arg453Cys)];[(Arg453His)]. Both presented clinically with typical lethal MARCH syndrome. Although a combination of missense and nonsense variants has been reported previously, this is the first report of biallelic missense CEP55 variants. These variants biallelically affected the same amino acid, Arg453, in the last 40 amino acids of CEP55. These residues are functionally important for CEP55 localization to the midbody during cell division, and may be associated with severe clinical outcomes. More cases of pathogenic CEP55 variants are needed to establish the genotype-phenotype correlation.

Mainland Japanese have been recognized as having dual ancestry, originating from indigenous Jomon people and immigrants from continental East Eurasia. Although migration from the continent to the Japanese Archipelago continued from the Yayoi to the Kofun period, our understanding of these immigrants, particularly their origins, remains insufficient due to the lack of high-quality genome samples from the Yayoi period, complicating predictions about the admixture process. To address this, we sequenced the whole nuclear genome of a Yayoi individual from the Doigahama site in Yamaguchi prefecture, Japan. A comprehensive population genetic analysis of the Doigahama Yayoi individual, along with ancient and modern populations in East Asia and Northeastern Eurasia, revealed that the Doigahama Yayoi individual, similar to Kofun individuals and modern Mainland Japanese, had three distinct genetic ancestries: Jomon-related, East Asian-related, and Northeastern Siberian-related. Among non-Japanese populations, the Korean population, possessing both East Asian-related and Northeastern Siberian-related ancestries, exhibited the highest degree of genetic similarity to the Doigahama Yayoi individual. The analysis of admixture modeling for Yayoi individuals, Kofun individuals, and modern Japanese respectively supported a two-way admixture model assuming Jomon-related and Korean-related ancestries. These results suggest that between the Yayoi and Kofun periods, the majority of immigrants to the Japanese Archipelago originated primarily from the Korean Peninsula.

Serotonin-transporter-linked polymorphic region (5-HTTLPR), a variable number of tandem repeats in the promoter region of serotonin transporter gene, is classified into short (S) and long (L) alleles. Initial case-control association studies claiming the risks of the S allele in depression and anxiety were not completely supported by recent studies. However, most studies, especially those on East Asian populations, have overlooked the complexity of 5-HTTLPR, which involves multiple different alleles with distinct functional properties. To address this issue, distinguishing multiple 5-HTTLPR alleles is essential. Here, using the 5-HTTLPR genotypes previously determined by exhaustive Sanger sequencing of approximately 1,500 Japanese subjects and their comprehensive SNP data, we constructed a method for 5-HTTLPR genotype imputation. We identified 28 tag SNPs for the imputation of four major 5-HTTLPR alleles, which collectively account for 97.6% of 5-HTTLPR alleles in the Japanese population. Our imputation method, achieved an accuracy of 0.872 in cross-validation, will contribute to association analysis of 5-HTTLPR in the Japanese subjects.

TXNDC15 encodes thioredoxin domain-containing protein 15, a protein disulfide isomerase that plays a role in ciliogenesis. Biallelic TXNDC15 variants have been reported in six individuals of Meckel syndrome (MKS) with perinatal lethal phenotypes, but have not been reported in patients with Joubert syndrome (JS). Here, we describe a 1-year-old female patient with compound heterozygous TXNDC15 variants demonstrating cerebellar vermis hypoplasia with the molar tooth sign, mild holoprosencephaly, and cortical abnormalities. She had severe developmental delay and epilepsy. Her clinical features were similar to those of JS, but distinctive forebrain abnormalities were also noted including mild holoprosencephaly and cortical abnormalities, which have been reported in a severe form of ciliopathy. Biallelic TXNDC15 variants manifest as overlapping phenotypes of JS and MKS, including the molar tooth sign, cortical dysgenesis, and mild holoprosencephaly. This report supports the hypothesis that JS and MKS are spectrum ciliopathy disorders with overlapping causative genes and hypomorphic TXNDC15 variants might contribute to JS.

We surveyed the status of the secondary finding (SF) disclosure in comprehensive genome profiling (CGP) in 2020. The situation has changed: increase in the number of hospitals that provide CGP, an update to the Comprehensive Tumor Genomic Profiling: Materials for Review of Secondary Findings (CTGPMRSF), and the addition of a liquid biopsy test, FoundationOne^® Liquid CDx (F1L). Moreover, the actual situation was unclear because the 2020 survey did not include all designated and cooperative hospitals. Herein, we conducted a questionnaire survey of all designated-core, designated, and cooperative hospitals to identify the current status and challenges concerning SF in the CGP in 2022. A total of 82.1% of the hospitals responded and 77.7% of the response was from cooperative hospitals. Approximately 80% of the hospitals used CTGPMRSF. SF disclosure, confirmatory test implementation, and SF confirmation rates were 12.4%, 31.6%, and 46.6% for FoundationOne^® CDx (F1CDx), respectively, and 6.8%, 31.8%, and 70.7% for F1L, respectively. The implementation rate of the confirmatory test was substantially higher in hospitals with genetic experts and in hospitals that could conduct confirmatory tests on the same day. Our survey provides insight into how SF is handled in Japan. The percentage of cases leading to confirmatory tests has gradually increased, although challenges such as insurance coverage limitations and varied understanding of SF among patients and healthcare providers persist. With the increasing use of whole-genome analysis, our findings will provide valuable insights into establishing an effective SF disclosure system.

Mutations in IBA57 disrupt iron-sulfur clusters maturation, causing a rare mitochondrial disease. Clinical manifestations vary from neonatal lethality to childhood-onset spastic paraparesis, yet the ethnic heterogeneity and natural history remain unclear, necessitating further exploration. This study aimed to delineate the genotype-phenotype correlation of IBA57 mutations by analyzing diverse clinical presentations. We report 11 Chinese patients and include literature-reported cases, totaling 61 patients enrolled for analysis. Clinical, neuroimaging, genetic, and disease progression information were collected. Among these, 46 presented as multiple mitochondrial dysfunctions syndrome 3 (MMDS3), with 58.7% originating from Chinese population. Based on disease course, we propose three clinical subtypes: neonatal, infant and childhood subtypes. Neonatal cases universally displayed hypotonia and respiratory distress at presentation, deceased within three months. Most infancy and childhood cases exhibited developmental regression and impaired motor function. Cavitating leukoencephalopathy was a typical neuroimaging finding in MMDS3 patients. The c.286 T > C mutation was reported in 85.2% of Chinese patients. A significantly lower mortality rate was observed compared to the non-Chinese group (P = 0.002), with a survival rate exceeding 90% at 5 years, indicating a relatively stable disease progression. Fifteen cases from three families manifested the spastic paraplegia 74 phenotype, demonstrating normal development before onset, with common clinical manifestations including spastic paraplegia (14/15), visual impairment (10/13), and peripheral neuropathy (9/13). In conclusion, this study indicates a hotspot mutation in Chinese and analyses the disease progression with different clinical subtypes.

Wilson's disease (WD) is a rare metabolic disorder caused by variations in the ATP7B gene. It usually manifests hepatic, neurologic, and psychiatric symptoms due to excessive copper accumulation. The prevalence of WD and its common variants differ across populations. This study aimed to examine these aspects of WD within the Thai population, where information has been limited. We reviewed ClinVar and the Wilson Disease Mutation Database, organizing variants classified as pathogenic or likely pathogenic in one or both databases as "relaxed" and "strict" lists. Allele frequencies were estimated from genotyping array data (Asian Screening Array: ASA; Illumina Corp, CA) of 6291 Thai subjects, which also underwent genotype imputation. The prevalence of WD in the Thai population was estimated assuming Hardy-Weinberg Equilibrium. The strict list yielded a prevalence of 1/24,128 (carrier frequency=1/78), while the relaxed list yielded a prevalence of 1/9971 (carrier frequency=1/50). The most common WD variants in Thai subjects were c.2333 G > T, c.3443 T > C, and c.813 C > A from the strict list, and c.3316 G > A and c.2605 G > A from the relaxed list. The ASA chip covered approximately 59 and 24% of WD variants from the strict and relaxed lists, respectively. Based on the estimated prevalence, a carrier screening program for WD is not currently required in Thailand. However, as genotyping services become more affordable and accessible, such a program would facilitate early identification, treatment, and prevention of WD.