Thomsen or Becker myotonia? A novel autosomal recessive nonsense mutation in the CLCN1 gene associated with a mild phenotype

We describe a large Brazilian consanguineous kindred with 3 clinically affected patients with a Thomsen myotonia phenotype. They carry a novel homozygous nonsense mutation in the CLCN1 gene (K248X). None of the 6 heterozygote carriers show any sign of myotonia on clinical evaluation or electromyography. These findings confirm the autosomal recessive inheritance of the novel mutation in this family, as well as the occurrence of phenotypic variability in the autosomal recessive forms of myotonia. Muscle Nerve, 2012

Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, Centro de Pesquisa, Inovacao e Difusao (FAPESP-CEPID)

Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, Centro de Pesquisa, Inovacao e Difusao (FAPESPCEPID)

Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)

Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)

Instituto Nacional de Ciencia e Tecnologia (INCT)

Instituto Nacional de Ciencia e Tecnologia (INCT)

FINEP

FINEP

Associacao Brasileira de Distrofia Muscular (ABDIM)

Associacao Brasileira de Distrofia Muscular (ABDIM)