Mutational Analyses on X-linked Adrenoleukodystrophy Reveal a Novel Cryptic Splicing and Three Missense Mutations in the ABCD1 Gene

Pediatr Neurol. 2013 Sep;49(3):185-90. doi: 10.1016/j.pediatrneurol.2013.04.021. Epub 2013 Jul 5.

Abstract

Background: X-linked adrenoleukodystrophy is caused by a defective peroxisomal membrane transporter, ABCD1, responsible for transporting very-long-chain fatty acid substrate into peroxisomes for degradation. The main biochemical defect, which is also one of the major diagnostic hallmarks, of X-linked adrenoleukodystrophy is the accumulation of saturated very-long-chain fatty acids in all tissues and body fluids.

Methods: Direct and reverse-transcribed polymerase chain reactions followed by DNA sequencing-based mutational analyses were performed on one Taiwanese and three Malaysian X-linked adrenoleukodystrophy families.

Results: A novel splicing donor site mutation (c.1272+1g>a) was identified in a Taiwanese X-linked adrenoleukodystrophy patient, resulting in a deletion of 121 bp and a premature stop codon (p.Val425fs*92) in messenger-RNA transcript. This deletion is caused by the activation of a cryptic splicing donor site in exon 4 of the ABCD1 gene, which is consistent with the prediction by several online algorithms. In addition, three previously described missense mutations (c.965T>C, c.1978C>T, and c.2006A>G), leading to aberrant ABCD1 of p.Leu322Pro, p.Arg660Trp, and p.His669Arg, were also identified in Malaysian probands.

Conclusions: This is the first report to unveil unequivocally that cryptic splicing-induced aberrant messenger-RNA carrying an internal frameshift deletion results from an intronic mutation in the ABCD1 gene. Furthermore, a polymorphism in intron 9 (c.1992-32c/t; refSNP: rs4898368) of the ABCD1 gene was commonly observed in both Taiwanese and Malaysian populations.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily D, Member 1
  • ATP-Binding Cassette Transporters / genetics*
  • Adrenoleukodystrophy / genetics*
  • DNA Mutational Analysis
  • Exons / genetics
  • Female
  • Genetic Predisposition to Disease / genetics*
  • Humans
  • Magnetic Resonance Imaging
  • Malaysia
  • Male
  • Mutation, Missense / genetics*
  • Numerical Analysis, Computer-Assisted
  • Sequence Deletion*
  • Taiwan

Substances

  • ABCD1 protein, human
  • ATP Binding Cassette Transporter, Subfamily D, Member 1
  • ATP-Binding Cassette Transporters