Detection of Turner syndrome using X-chromosome inactivation specific differentially methylated CpG sites: A pilot study

Clin Chim Acta. 2017 May:468:174-179. doi: 10.1016/j.cca.2017.03.008. Epub 2017 Mar 8.

Abstract

Background: Early diagnosis of Turner syndrome (TS) may improve preventive measures and treatment. X-chromosome inactivation specific differentially methylated CpG sites (XIDMSs) that are high methylated in inactive X chromosomes (Xi) and unmethylated in active X chromosomes (Xa) may be potential makers for TS detection.

Methods: The candidate XIDMSs were screened from 9 male and 12 female DNA samples with normal karyotypes using the Illumina 450k array and validated by bisulfite sequencing PCR and pyrosequencing assay. X chromosome dosage was calculated according to the methylation level of multiple XIDMSs.

Results: Overall, 108 candidate XIDMSs were screened by the 450k array. Validations indicated that XIDMSs gathered and formed the X-chromosome inactivation specific differentially methylated regions (XIDMRs). Using 3 XIDMRs at SAT1, UXT and UTP14A loci, 36 TS, 22 normal female and 6 male samples were analyzed. Methylation levels of the 20 XIDMSs in the XIDMRs could distinguish between TS and normal female DNA samples, the X chromosome dosage was consistent with karyotyping data. Analyzing samples of 2 triple X syndrome and 3 Klinefelter syndrome patients suggested that this method could be used to detect X chromosome aneuploids other than TS.

Conclusions: XIDMSs are widely spread along the X chromosome and might be effective markers for detection of TS and other X chromosome aneuploids.

Keywords: DNA methylation; Turner syndrome; X chromosome aneuploids; X-chromosome inactivation.

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • CpG Islands / genetics*
  • DNA Methylation*
  • Female
  • High-Throughput Nucleotide Sequencing
  • Humans
  • Male
  • Pilot Projects
  • Sequence Analysis, DNA
  • Turner Syndrome / diagnosis*
  • Turner Syndrome / genetics*
  • X Chromosome Inactivation / genetics*