Human Genome Variation最新文献

Here, we report a novel PROS1 splicing mutation in a patient with type I protein S deficiency. Qualitative and quantitative analysis of pathogenic splicing variants at the mRNA level was performed by long-range PCR-based targeted DNA and RNA sequencing. A base substitution in the exon 4 splicing donor site activates a potential splicing donor site in intron 4, resulting in an in-frame insertion of 48 bases (16 amino acids).

Biallelic IGFALS variants lead to acid‒labile subunit (ALS) deficiency characterized by growth hormone resistance with or without delayed puberty. Here, we report a prepubertal boy with a homozygous 2-amino acid deletion within the fourth N-glycosylation motif (c.1103_1108del, p.N368_S370delinsT) associated with parental consanguinity. He showed short stature consistent with ALS deficiency. This case expands the mutation spectrum of IGFALS to include the elimination of only one N-glycosylation motif of ALS.

Gelatinous drop-like corneal dystrophy (GDLD) is a rare autosomal recessive eye disease. GDLD is characterized by the loss of barrier function in corneal epithelial cells (CECs) and amyloid deposition due to pathogenic variants in the TACSTD2 gene. Limbal stem cell transplantation (LSCT) has been suggested as an effective therapeutic alternative for patients with GDLD. However, despite LSCT, amyloid deposition recurs in some patients. The pathogenesis of recurrence is poorly studied. We present the case of a patient with GDLD. Genetic analysis revealed a homozygous deletion, NM_002353.3:c.653del, in the TACSTD2 gene. Functional analysis in a cell model system revealed the loss of the transmembrane domain and subcellular protein mislocalization. The patient with GDLD underwent direct allogeneic LSCT with epithelial debridement followed by deep anterior lamellar keratoplasty 10 months later due to amyloid deposition and deterioration of vision. Taken together, the results of transcriptome analysis and immunofluorescence staining of post-LSCT corneal sample with amyloid deposits obtained during keratoplasty demonstrated complete restoration of wild-type TACSTD2 expression, indicating that donor CECs replaced host CECs. Our study provides experimental evidence that amyloid deposition can recur after LSCT despite complete restoration of wild-type TACSTD2 expression.

Tandem nucleotide repeat (TNR) expansions, particularly the CNG nucleotide configuration, are associated with a variety of neurodegenerative disorders. In this study, we aimed to identify novel unstable CNG repeat loci associated with the neurogenetic disorder spinocerebellar ataxia (SCA). Using a computational approach, 15,069 CNG repeat loci in the coding and noncoding regions of the human genome were identified. Based on the feature selection criteria (repeat length >10 and functional location of repeats), we selected 52 repeats for further analysis and evaluated the repeat length variability in 100 control subjects. A subset of 19 CNG loci observed to be highly variable in control subjects was selected for subsequent analysis in 100 individuals with SCA. The genes with these highly variable repeats also exhibited higher gene expression levels in the brain according to the tissue expression dataset (GTEx). No pathogenic expansion events were identified in patient samples, which is a limitation given the size of the patient group examined; however, these loci contain potential risk alleles for expandability. Recent studies have implicated GLS, RAI1, GIPC1, MED15, EP400, MEF2A, and CNKSR2 in neurological diseases, with GLS, GIPC1, MED15, RAI1, and MEF2A sharing the same repeat loci reported in this study. This finding validates the approach of evaluating repeat loci in different populations and their possible implications for human pathologies.

Acid sphingomyelinase deficiency (ASMD) and Gaucher disease (GD) are lysosomal storage disorders associated with hepatosplenomegaly and thrombocytopenia. The incidences of ASMD and GD are known to be particularly high in the Ashkenazi Jewish population. Conversely, the number of reported patients with these diseases has been limited in Asian countries, including Japan. Here, we reviewed the allele frequencies of pathogenic variants causing ASMD and GD in the Japanese population and populations with various ancestry backgrounds using the Japanese Multi-Omics Reference Panel 54KJPN and the Genome Aggregation Database v4.0.0. The estimated carrier frequencies of ASMD- and GD-related variants were 1/180 and 1/154 in Japanese individuals, equivalent to disease occurrence frequencies of 1/128,191 and 1/94,791 individuals, respectively. These frequencies are much higher than previously expected. Our data also suggest that there are more patients with a milder form of ASMD and nonspecific clinical findings who have not yet been diagnosed.

The integration of structural variations (SVs) in statistical genetics provides an opportunity to understand the genetic factors influencing complex human traits and disease. Recent advances in long-read technology and variant calling methods for short reads have improved the accurate discovery and genotyping of SVs, enabling their use in expression quantitative trait loci (eQTL) analysis and genome-wide association studies (GWAS). Mobile elements are DNA sequences that insert themselves into various genome locations. Insertional polymorphisms of mobile elements between humans, called mobile element variations (MEVs), contribute to approximately 25% of human SVs. We recently developed a variant caller that can accurately identify and genotype MEVs from biobank-scale short-read whole-genome sequencing (WGS) datasets and integrate them into statistical genetics. The use of MEVs in eQTL analysis and GWAS has a minimal impact on the discovery of genome loci associated with gene expression and disease; most disease-associated haplotypes can be identified by single nucleotide variations (SNVs). On the other hand, it helps make hypotheses about causal variants or effector variants. Focusing on MEVs, we identified multiple MEVs that contribute to differential gene expression and one of them is a potential cause of skin disease, emphasizing the importance of the integration of MEVs in medical genetics. Here, I will provide an overview of MEVs, MEV calling from WGS, and the integration of MEVs in statistical genetics. Finally, I will discuss the unanswered questions about MEVs, such as rare variants.

Germline loss-of-function mutations in USP9X have been reported to cause a wide spectrum of congenital anomalies. Here, we report a Japanese girl with a novel heterozygous nonsense mutation in USP9X who exhibited intellectual disability with characteristic craniofacial abnormalities, including hypotelorism, brachycephaly, hypodontia, micrognathia, severe dental crowding, and an isolated submucous cleft palate. Our findings provide further evidence that disruptions in USP9X contribute to a broad range of congenital craniofacial abnormalities.

Neurofibromatosis type 1 (NF1) is an autosomal dominant nevus disease characterized by multiple manifestations, primarily café-au-lait macules and neurofibromas. Here, we present the case of an NF1 patient with 47,XYY mosaicism whose diagnosis was prompted by café-au-lait macules on the skin and mandibular neurofibromas. Targeted next-generation sequencing of the patient's blood sample revealed a novel frameshift mutation in NF1 (NM_000267.3:c.6832dupA:p.Thr2278Asnfs*8) that is considered a pathogenic variant.

A 3.5-Mb microdeletion in Xq22 was identified in a female patient with early-onset neurological disease trait (EONDT). The patient exhibited developmental delay but no hypomyelination despite PLP1 involvement in the deletion. However, the clinical features of the patient were consistent with those of TCEAL1 loss-of-function syndrome. The breakpoint junction was analyzed using long-read sequencing, and blunt-end fusion was confirmed.

Short- and long-read sequencing technologies are routinely used to detect DNA variants, including SNVs, indels, and structural variations (SVs). However, the differences in the quality and quantity of variants detected between short- and long-read data are not fully understood. In this study, we comprehensively evaluated the variant calling performance of short- and long-read-based SNV, indel, and SV detection algorithms (6 for SNVs, 12 for indels, and 13 for SVs) using a novel evaluation framework incorporating manual visual inspection. The results showed that indel-insertion calls greater than 10 bp were poorly detected by short-read-based detection algorithms compared to long-read-based algorithms; however, the recall and precision of SNV and indel-deletion detection were similar between short- and long-read data. The recall of SV detection with short-read-based algorithms was significantly lower in repetitive regions, especially for small- to intermediate-sized SVs, than that detected with long-read-based algorithms. In contrast, the recall and precision of SV detection in nonrepetitive regions were similar between short- and long-read data. These findings suggest the need for refined strategies, such as incorporating multiple variant detection algorithms, to generate a more complete set of variants using short-read data.