Key result
A de novo T1313M sodium channel mutation was identified in a patient with typical symptoms of paramyotonia congenita despite a negative family history.
Case Report (n=1)
Evaluation for paramyotonia congenita should be performed in patients with typical symptoms even if the family history is negative, as de novo mutations can occur.
Supports evaluation despite negative family history; extends SCN4A variant spectrum but leaves open generalizability from single case.
A Japanese man with a negative family history of paramyotonia congenita (PMC) was evaluated for symptoms of cold-induced weakness and stiffness. Exercise testing revealed findings characteristic of PMC, and a genetic analysis was therefore performed. A well-known sodium channel mutation for PMC (T1313M) was identified in the patient, but was absent in his biological parents. These data demonstrate the occurrence of a de novo mutation, suggesting that evaluation for PMC should be performed in patients with typical symptoms even if the family history is negative.
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Fukudome et al. (2003) conducted a case report in Paramyotonia congenita (n=1). De novo T1313M sodium channel mutation was evaluated on Presence of T1313M mutation. A de novo T1313M sodium channel mutation was identified in a patient with typical symptoms of paramyotonia congenita despite a negative family history.
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