Chinese family with diffuse oesophageal leiomyomatosis: A new COL4A5/COL4A6 deletion and a case of gonosomal mosaicism

Wei Liu, John K.L. Wong, Qiuming He, Emily H.M. Wong, Clara S.M. Tang, Ruizhong Zhang, Man ting So, Kenneth K.Y. Wong, John Nicholls, Stacey S. Cherny, Pak C. Sham, Paul K. Tam, Maria Mercè Garcia-Barcelo, Huimin Xia

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Diffuse oesophageal leiomyomatosis (DOL) is a rare disorder characterized by tumorous overgrowth of the muscular wall of the oesophagus. DOL is present in 5 % of Alport syndrome (AS) patients. AS is a rare hereditary disease that involves varying degrees of hearing impairment, ocular changes and progressive glomerulonephritis leading to renal failure. In DOL-AS patients, the genetic defect consists of a deletion involving the COL4A5 and COL4A6 genes on the X chromosome. Case presentation: We report a two-generation family (4 individuals; parents and two children, one male and one female) with two members (mother and son) affected with oesophageal leiomyomatosis. Signs of potential renal failure, which characterizes AS, were only apparent in the index patient (son) 2 years and three months after the initial diagnosis of DOL. Blood DNA from the four family members were submitted to exome sequencing and array genotyping to perform a genome wide screening for disease causal single nucleotide (SN) and copy number (CN) variations. Analyses revealed a new 40kb deletion encompassing from intron 2 of COL4A5 to intron 1 of COL4A6 at Xq22.3. The breakpoints were also identified. Possible confounding pathogenic exonic variants in genes known to be involved in other extracellular matrices disorders were also shared by the two affected individuals. Meticulous analysis of the maternal DNA revealed a case of gonosomal mosaicism. Conclusions: This is the first report of gonadosomal mosaicism associated to DOL-AS.

Original languageEnglish
Article number49
JournalBMC Medical Genetics
Volume16
Issue number1
DOIs
StatePublished - 16 Jul 2015
Externally publishedYes

Keywords

  • COL4A5
  • COL4A6
  • Copy number variation
  • Gonosomal mosaicism
  • Isolated diffuse oesophageal leiomyomatosis
  • Whole exome sequencing

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