The value of MLPA in Waardenburg syndrome

Genet Test. 2007 Summer;11(2):179-82. doi: 10.1089/gte.2006.0531.

Abstract

Waardenburg syndrome (WS) is an autosomal-dominant neurocristopathy characterized by sensorineural hearing loss, pigmentary abnormalities of the iris, hair, and skin, and is responsible for about 3% of congenital hearing loss. Point mutations in PAX3 have been identified in more than 90% of affected individuals with WS Type 1/WS Type 3. MITF point mutations have been identified in 10-15% of individuals affected with WS Type 2 (lacking dystopia canthorum). Multiplex ligation-dependent probe amplification (MLPA) is now a standard technology in the molecular genetics laboratory to detect copy number changes in targeted genes. We employed MLPA for PAX3 and MITF in a cohort of patients submitted with a diagnosis of WS1, 2 or 3 who were sequence negative for PAX3 and/or MITF. All coding exons of PAX3 and exons 1, 2, 3, and 10 of MITF were included in the MLPA assay. MLPA on 48 patients with WS 1 or 3 revealed 3 PAX3 whole gene deletions (2 WS1; 1 WS3), 2 PAX3 partial gene deletions [WS1, exon 1 and promoter (1st report); WS1, exons 5-9], and 1 partial MITF deletion ("WS1", exons 3-10) (6/48 approximately 12.5%). MLPA on 41 patients with WS2 and 20 patients submitted with a diagnosis of either WS1 or WS2 revealed no copy number changes. The detection of both partial and whole gene deletions of PAX3/MITF in this clinical cohort increases the mutation detection yield by at least 6% and supports integrating MLPA into clinical molecular testing primarily for patients with WS1 and 3.

MeSH terms

  • DNA / blood
  • DNA / genetics
  • DNA / isolation & purification
  • Female
  • Gene Amplification*
  • Gene Deletion
  • Humans
  • Male
  • Microphthalmia-Associated Transcription Factor / genetics*
  • Mutation
  • PAX3 Transcription Factor
  • Paired Box Transcription Factors / genetics*
  • Pedigree
  • Point Mutation
  • Polymerase Chain Reaction
  • Waardenburg Syndrome / genetics*

Substances

  • MITF protein, human
  • Microphthalmia-Associated Transcription Factor
  • PAX3 Transcription Factor
  • PAX3 protein, human
  • Paired Box Transcription Factors
  • DNA