Abstract
BackgroundCopy number variations (CNVs) can contribute to human phenotype, phenotypic diversity and disease susceptibility, while others may benign. In the current study, an attempt to investigate the pathogenicity of CNVs in chromosome Xp22.31 was explored.MethodsG-banding and SNP-array techniques were used to analyze chromosome karyotypes and CNVs in fetuses. Parents associate with five different pedigrees possessing high risk factors in pregnancy were considered with such parameters as advanced age, high risk of serological screening and ultrasound abnormalities.ResultsThe fetuses’ amniotic fluid karyotypes were 46, XX and those of their parents with the five pedigrees revealed no abnormalities. Here, we noticed a series of individuals with Xp22.31 duplications ranging from 534.6 kb to 1.6 Mb. It was detected through SNP array that the fetuses in Pedigree 1 and 2 had ~ 600 kb duplications in the Xp22.31 region of their X chromosomes which contained two OMIM genes, HDHD1 (OMIM: 306480) and part of STS (OMIM: 300747). The fetuses of Pedigrees 3, 4 and 5 had 1.6 Mb duplication in the same chromosome which contained four OMIM genes: HDHD1 (OMIM: 306480), STS (OMIM: 300747), PNPLA4 (OMIM: 300102) and VCX (OMIM: 300229). The duplications in the fetuses of Pedigrees 1 and 5 were inherited from the non-phenotypic parents. Pedigrees 3 and 4 refused to perform parental verification. Finally, four of the five pedigrees continue towards pregnancy with no abnormalities being observed during followed-ups.ConclusionOur study first showed duplications of Xp22.31 in Chinese population. Clinical and genetic investigation on five different pedigrees, we consider the duplication of these fragments as likely benign copy number variants (CNVs). We suggest that the duplications of Xp22.31 with recurrent duplication as a benign CNVs .
Highlights
Copy number variations (CNVs) can contribute to human phenotype, phenotypic diversity and disease susceptibility, while others may benign
Genomic instability is a feature of Xp22.31 region wherein deletions or mutations are associated with X-linked ichthyosis (OMIM 308100, XLI), a dermatologic disorder presenting with dry, scaly skin due to a deficiency of the enzyme steroid sulfatase (STS), usually arising from a mutation in the STS gene [2,3,4]
The SNP array detecting results demonstrated that the Pedigree 1 fetus had a 534.6 kb duplication in the Xp22.31 region of the X chromosome (ChrX: 6538, 033–7, 072, 640) (Figs. 1 and 2), containing two Online Mendelian inhertance in Man (OMIM) genes: HDHD1 (OMIM: 306480) and part of STS (OMIM: 300747) which crossed the first exon
Summary
Copy number variations (CNVs) can contribute to human phenotype, phenotypic diversity and disease susceptibility, while others may benign. The Xp22.31 segment of the human X chromosome short arm is a region of high instability with frequent rearrangement [1]. Genomic instability is a feature of Xp22.31 region wherein deletions or mutations are associated with X-linked ichthyosis (OMIM 308100, XLI), a dermatologic disorder presenting with dry, scaly skin due to a deficiency of the enzyme steroid sulfatase (STS), usually arising from a mutation in the STS gene [2,3,4]. Xp22.31 has been reported in the healthy general population and been described in individuals with pathological conditions [13]. The consequences of this repetitive region are still unclear. Four of the five pedigrees continued towards pregnancy, following which no obvious clinical abnormalities were observed
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