A symptomatic male carrier of Duchenne muscular dystrophy with Klinefelter's syndrome mimicking Becker muscular dystrophy

Neuromuscul Disord. 2021 Jul;31(7):666-672. doi: 10.1016/j.nmd.2021.04.006. Epub 2021 Apr 27.

Abstract

Duchenne and Becker muscular dystrophy (DMD/BMD) are commonly inherited muscle disorders. We report a 31-year-old male who had muscle symptoms with left-right differences and intellectual disability. He was diagnosed with BMD at age 15 primarily based on muscle biopsy findings. A few years later, DMD gene analysis revealed that he was a heterozygous carrier of a normal copy of the gene and a mutated copy with an exon 45-54 deletion, which is expected to result in an out-of-frame mutation. A karyotype analysis was compatible with XXY Klinefelter's syndrome. The analysis of X-chromosome inactivation (XCI) using his skeletal muscle sample revealed a skewed XCI pattern. This is the first reported case of a symptomatic male carrier of DMD caused by skewed XCI in Klinefelter's syndrome with a genetically proven heterozygous mutation of the DMD gene. The skewed XCI pattern could also explain the left-right differences in skeletal muscle symptoms observed in this patient.

Keywords: Becker muscular dystrophy; Duchenne muscular dystrophy; Klinefelter's syndrome; Symptomatic carrier.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biopsy
  • Diagnosis, Differential
  • Dystrophin / genetics
  • Exons
  • Frameshift Mutation
  • Gene Deletion
  • Heterozygote
  • Humans
  • Intellectual Disability / genetics
  • Klinefelter Syndrome / diagnosis*
  • Male
  • Muscle, Skeletal / pathology
  • Muscular Dystrophy, Duchenne / diagnosis*
  • Mutation
  • Pedigree
  • Phenotype

Substances

  • Dystrophin