Endoplasmic reticulum retention of xylosyltransferase 1 (XYLT1) mutants underlying Desbuquois dysplasia type II

Nesreen K. Al-Jezawi, Bassam R. Ali, Lihadh Al-Gazali

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

Desbuquois syndrome is a heterogeneous rare type of skeletal dysplasia with a prevalence of less than 1 in 1,000,000 individuals. It is characterized by short-limbed dwarfism, dysmorphic facial features, and severe joint laxity. Two types have been recognized depending on the presence of distinctive carpal and phalangeal features. Mutations in the calcium activated nucleotidase 1 (CANT1) have been found to be responsible for type I and lately, for the Kim type of Desbuquois dysplasia. In addition, a number of Desbuquois dysplasia type II patients have been attributed to mutations in xylosyltransferase 1, encoded by the XYLT1 gene, an enzyme that catalyzes the transfer of UDP-xylose (a marker of cartilage destruction) to serine residues of an acceptor protein, essential for the biosynthesis of proteoglycans. We report here a patient with features consistent with Desbuquois dysplasia II including short long bones, flat face, mild monkey wrench appearance of the femoral heads. Whole exome sequencing revealed a novel homozygous duplication of a single nucleotide in XYLT1 gene (c.2169dupA). This variant is predicted to result in a frame-shift and stop codon p.(Val724Serfs*10) within the xylosyltransferase catalytic domain. Immunoflourescence staining of HeLa cells transfected with mutated XYLT1 plasmids constructs of the current as well as the previously reported missense mutations (c.1441C>T, p.(Arg481Trp) and c.1792C>T, p.(Arg598Cys)), revealed aberrant subcellular localization of the enzyme compared to wild-type, suggesting endoplasmic reticulum retention of these mutants as the likely mechanism of disease.

Original languageEnglish
Pages (from-to)1773-1781
Number of pages9
JournalAmerican Journal of Medical Genetics, Part A
Volume173
Issue number7
DOIs
Publication statusPublished - Jul 2017

Keywords

  • Desbuquois dysplasia (DBQD)
  • XYLT1 (xylosyltransferase)
  • autosomal recessive
  • skeletal dysplasia

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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