Identification, molecular characterization and segregation analysis of a variant DMPK pre-mutation allele in a three-generation Italian family

Luana Fontana, Massimo Santoro, Maria Rosaria D'Apice, Francesca Peluso, Giulia Gori, Amelia Morrone, Giuseppe Novelli, Laura Dosa, Annalisa Botta

Research output: Contribution to journalArticlepeer-review

Abstract

DM1 is an autosomal dominant multisystemic disease caused by an unstable CTG repeat expansion in the 3'-untranslated region (UTR) of the DMPK gene. The complex variant DMPK expanded the alleles containing CAG, CCG, CTC and/or GGC interruptions repetition sequences have been reported in 3-8% of DM1 patients. To date, very few information is available about the frequency and clinical consequences of pre-mutated DMPK variant allele. In this study, we describe a three-generation Italian family showing the segregation of an interrupted DMPK allele within the premutation range. TP-PCR with primers complementary to CCG repetitions and direct sequencing allow us to identify a hetero-triplet (CTG)6(CCGCTG)15(CTG)5 repeat structure. The haplotype analysis demonstrated that this variant allele is associated with the European founder DM1 haplotype. The pyrosequencing analysis of the CpG islands contained in the flanking regions of the CTG array, did not show the presence of a cis effect of the CCG interruptions on the methylation profile of the DM1 locus. The analysis of both meiotic transmissions, one maternal and one paternal, revealed the intrafamilial stability of the DM1 premutation among relatives. Our findings further support the hypothesis of a stabilizing effect of CCG interruptions on the mutational dynamics of the DM1 locus, also in intermediate DMPK alleles.

Original languageEnglish
Pages (from-to)13-18
Number of pages6
JournalActa Myologica
Volume39
Issue number1
DOIs
Publication statusPublished - Jan 1 2020

Keywords

  • DMPK variant alleles
  • Methylation
  • Premutation
  • TP-PCR analysis

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

Fingerprint

Dive into the research topics of 'Identification, molecular characterization and segregation analysis of a variant DMPK pre-mutation allele in a three-generation Italian family'. Together they form a unique fingerprint.

Cite this