CAPN3 mRNA processing alteration caused by splicing mutation associated with novel genomic rearrangement of Alu elements

J Hum Genet. 2012 Feb;57(2):92-100. doi: 10.1038/jhg.2011.129. Epub 2011 Dec 8.

Abstract

Recessive mutations of CAPN3 gene are reported to be responsible for limb girdle muscular dystrophy type 2A (LGMD2A). In all, 15-25% of intronic nucleotide changes identified in this gene were investigated by in silico analysis, but occasionally supported by experimental data or reported in some cases as a polymorphism. We report here genetic and transcriptional analyses in three Tunisian patients belonging to the same consanguineous family sharing the same mutation c.1194-9 A>G and Alu repeats insertion in intron 7 of CAPN3 gene. Reverse transcriptase-PCR experiments performed on total RNA from the patient's muscle biopsy showed retention of the eight last nucleotides of intron 9 in the CAPN3 transcript lacking the first seven exons. Our results provide evidence regarding the potential involvement of Alu elements in aberrant processing of pre-mRNA owing to the disruption of pre-existing intronic splicing regulatory elements. We also demonstrated variable mRNA alternative splicing among tissues and between LGMD2A patients. A deep intronic variation and rearrangement have been reported in the literature as causing genetic diseases in humans. However, this is the first report on a potential pathogenic CAPN3 gene mutation resulting from an Alu insertion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Alternative Splicing*
  • Alu Elements
  • Base Sequence
  • Calpain / genetics*
  • Calpain / metabolism
  • Case-Control Studies
  • Child
  • Consanguinity
  • Female
  • Humans
  • Molecular Sequence Data
  • Muscle Proteins / genetics*
  • Muscle Proteins / metabolism
  • Muscular Dystrophies, Limb-Girdle / genetics*
  • Mutagenesis, Insertional
  • Point Mutation*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism*
  • Sequence Analysis, DNA
  • Young Adult

Substances

  • Muscle Proteins
  • RNA, Messenger
  • CAPN3 protein, human
  • Calpain