Identification and characterization of two novel JARID1C mutations: Suggestion of an emerging genotype-phenotype correlation

Sinitdhorn Rujirabanjerd, John Nelson, Patrick S. Tarpey, Anna Hackett, Sarah Edkins, F. Lucy Raymond, Charles E. Schwartz, Gillian Turner, Shigeki Iwase, Yang Shi, P. Andrew Futreal, Michael R. Stratton, Jozef Gecz

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48 Citations (Scopus)

Abstract

Mental retardation (MR) is characterized by cognitive impairment with an IQ 70. Many of the major causes are genetically determined and the 30% male excess suggests that mutations in genes carried on the X chromosome are disproportionably represented. One such gene, jumonji AT-rich interactive domain 1C (JARID1C) on Xp11.2, has been identified in families with X-linked MR (XLMR), with 18 different mutations reported to date. As part of a systematic resequencing of 720 genes in 208 XLMR families of the International Genetic of Learning Disability (IGOLD) consortium, two novel nucleotide changes in the JARID1C coding region were identified, with the nucleotide changes segregating with the disease phenotype in the two families. The first mutation is a single-nucleotide insertion in exon 21 (c.3258-3259insC p.K1087fs 43) causing a frameshift and resulting in a premature termination codon (PTC). Such PTC-containing mRNAs are generally degraded by nonsense-mediated mRNA decay (NMD) surveillance, but our results show that this is not the case with this mutation. The other change is a single-nucleotide substitution in exon 12 (c.1160C>A) in a published family with nonsyndromic MR, MRX13. This change occurs in a highly conserved amino acid, with proline (P) being substituted by threonine (T) (p.P544T). Functional analysis shows that this amino-acid substitution compromises both tri-and didemethylase activity of the JARID1C protein. We conclude that the two novel changes impair JARID1C protein function and are disease-causing mutations in these families.

Original languageEnglish
Pages (from-to)330-335
Number of pages6
JournalEuropean Journal of Human Genetics
Volume18
Issue number3
DOIs
Publication statusPublished or Issued - Mar 2010
Externally publishedYes

Keywords

  • JARID1C
  • JmjC domain
  • Mutation analysis
  • X-linked mental retardation

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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