Co-occurrence of CAPN3 homozygous mutation and CCTG expansion in the CNBP gene in a patient with muscular dystrophy

Abstract

Abstract Muscular dystrophy is a group of heterogeneous diseases that cause progressive muscle weakness and atrophy. Many types of muscular dystrophy is distinguished involving Duchenne/Becker, myotonic, limb-girdle, congenital, or facioscapulohumeral muscular dystrophies. Different molecular techniques, including next-generation sequencing (NGS) were performed to identify the genetic cause of Polish patient with limb–girdle muscle weakness and atrophy. Homozygous pathogenic mutation c.550delA, (p.Thr184ArgfsTer36) in the CAPN3 gene as well as a heterozygous expansion of a CCTG repeat of the CNBP gene in this patient had been identified. Segregation analysis showed both maternal and paternal heterozygous carriers for CAPN3 mutation, and a maternally inherited CNBP expansion. Here, we report on the first patient who carried both a homozygous mutation in the CAPN3 and CCTG expansion in the CNBP gene, suggesting the co-occurrence of recessive limb-girdle muscular dystrophy 1 and myotonic dystrophy 2 (DM2) in a single patient. In general, this phenomenon is considered as uncommon, although is possible and, therefore, should be taken into consideration in those populations with a relatively high prevalence of DM2.