Human Genome Variation最新文献

Genes with multiple copies are likely to be maintained by stabilizing selection, which puts a bound to unlimited expansion of copy number. We designed a model in which copy number variation is generated by unequal recombination, which fits well with several genes surveyed in three human populations. Based on this theoretical model and computer simulations, we were interested in determining whether the gene copy number distribution in the derived European and Asian populations can be explained by a purely demographic scenario or whether shifts in the distribution are signatures of adaptation. Although the copy number distribution in most of the analyzed gene clusters can be explained by a bottleneck, such as in the out-of-Africa expansion of Homo sapiens 60-10 kyrs ago, we identified several candidate genes, such as AMY1A and PGA3, whose copy numbers are likely to differ among African, Asian, and European populations.

Loss-of-function germline variants of MLH1 cause Lynch syndrome. Here, we present the case of a 43-year-old male patient diagnosed with cecal and transverse colon adenocarcinomas. The characteristics of the case met the revised Bethesda guidelines, and the tumors demonstrated a high frequency of microsatellite instability. Genetic testing for mismatch repair genes (indicative of Lynch syndrome) revealed a novel heterozygous germline pathogenic variant, NM_000249.4:c.856A>T/NP_000240.1:p.(Lys286Ter), in MLH1.

Hereditary ataxias are classified by inheritance patterns into autosomal dominant, autosomal recessive, X-linked, and mitochondrial modes of inheritance. A large group of adult hereditary ataxias have autosomal dominant inheritance, and autosomal recessive cerebellar ataxias (ARCAs) are rare, with greater diversity in phenotypic and genotypic features. Therefore, comprehensive genetic testing is useful for identifying the genes responsible for ARCAs. We identified two novel pathogenic variants of the SQSTM1 and SYNE1 genes via whole-exome sequencing in patients with ARCAs.

We report a case of Wilson disease (WD) with dilated cardiomyopathy in which whole-genome sequencing (WGS) revealed the rare co-occurrence of two novel compound heterozygous ATP7B pathogenic variants (NM_001005918.3:c.2250del/p.N751Tfs*9 and c.3496C>T/p.L1166F) and a known FLNC pathogenic variant. Our results highlight the usefulness of WGS, even in the diagnosis of well-characterized genetic diseases such as WD.

Type 2 spinal muscular atrophy with lower extremity dominance (SMALED2) is caused by bicaudal D cargo adaptor 2 (BICD2) variants. However, the SMALED2 genotype and phenotype correlation have not been thoroughly characterized. We identified de novo heterozygous BICD2 missense variants in two fetuses with severe, prenatally diagnosed multiple arthrogryposis congenita. This report provides further insights into the genetics of this rare disease.

We report a case of severe Aicardi-Goutières syndrome caused by a novel homozygous RNASEH2B intronic variant, NC_000013.10(NM_024570.4):c.65-13G > A p.Glu22Valfs*5. The patient was born with pseudo-TORCH symptoms, including intracranial calcification, cataracts, and hepatosplenomegaly. Furthermore, the patient exhibited profound intellectual impairment and died at 14 months due to aspiration pneumonia accompanied by interstitial lung abnormalities. The severity of the patient's symptoms underscores the critical role of the C-terminal region of RNase H2B.

Tetrasomy X or 48,XXXX is a rare sex chromosome aneuploidy. The parental origin of tetrasomy X in a female patient with developmental delay was analyzed; all four X chromosomes were derived from the mother, and there were no paternally derived sex chromosomes. This finding indicates a rare incidental co-occurrence of maternal and paternal nondisjunction or polysomy rescue. The mechanism of 48,XXYY, which is related to developmental delay in males, was analyzed for comparison.

ApoA-I amyloidosis is an extremely rare form of systemic amyloidosis that commonly involves the heart, kidneys, and liver. ApoA-I amyloidosis is caused by amyloidogenic variants of APOA1 that are inherited in an autosomal dominant manner. Here, we report a 69-year-old man with sporadic cardiac amyloidosis who was born to consanguineous parents and carried a homozygous variant of p.Leu202Arg in APOA1.

Charcot-Marie-Tooth disease type 2Z is caused by MORC2 mutations and presents with axonal neuropathy. MORC2 mutations can also manifest as developmental delay, impaired growth, dysmorphic facies, and axonal neuropathy (DIGFAN). We report a patient exhibiting an intermediate phenotype between these diseases associated with a novel MORC2 variant. A literature review revealed that the genotype‒phenotype correlation in MORC2-related disorders is complex and that the same mutation can cause a variety of phenotypes.

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).