Novel BICD2 mutation in a Japanese family with autosomal dominant lower extremity-predominant spinal muscular atrophy-2

Mieko Yoshioka, Naoya Morisada, Daisaku Toyoshima, Hajime Yoshimura, Hisahide Nishio, Kazumoto Iijima, Yasuhiro Takeshima, Tomoko Uehara, Kenjiro Kosaki

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4 Citations (Scopus)

Abstract

Introduction: The most common form of spinal muscular atrophy (SMA) is a recessive disorder caused by SMN1 mutations in 5q13, whereas the genetic etiologies of non-5q SMA are very heterogenous and largely remain to be elucidated. We present a father and son with atrophy and weakness of the lower leg muscles since infancy. Genetic studies in this family revealed a novel BICD2 mutation causing autosomal dominant lower extremity-predominant SMA type 2. Patients: The proband was the father, aged 30, and the son was aged 3. Both of them were born uneventfully to nonconsanguineous parents. While the father first walked at the age of 19 months, the son was unable to walk at age 3 years. In both, knee and ankle reflexes were absent and sensation was intact. Serum creatine kinase levels were normal. The son showed congenital arthrogryposis and underwent orthopedic corrections for talipes calcaneovalgus. Investigation of the father at the age of 5 years revealed normal results on nerve conduction studies and sural nerve biopsy. Electromyography showed chronic neurogenic change, and muscle biopsy showed features suggestive of denervation. The father was diagnosed clinically with a sporadic distal SMA. Follow-up studies showed very slow progression. Investigations and results: Next-generation and Sanger sequencing revealed a deleterious mutation in BICD2: c.1667A>G, p.Tyr556Cys, in this family. Discussion: BICD2 is a cytoplasmic conserved motor-adaptor protein involved in anterograde and retrograde transport along the microtubules. Next-generation sequencing will further clarify the genetic basis of non-5q SMA.

Original languageEnglish
JournalBrain and Development
DOIs
Publication statusAccepted/In press - 2017 Jan 1

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Keywords

  • Autosomal dominant lower extremity-predominant spinal muscular atrophy type 2
  • BICD2 mutation
  • Motor-adaptor protein
  • Next-generation sequencing
  • Non-5q spinal muscular atrophy
  • SMN1 in 5q13
  • Spinal muscular atrophy

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Developmental Neuroscience
  • Clinical Neurology

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