The Arg222Trp mutation in the SCN4A gene can cause an atypical phenotype of familial hypokalemic periodic paralysis characterized by severe respiratory insufficiency, incomplete penetrance in females, and unresponsiveness to acetazolamide.
May guide therapy selection in acetazolamide-refractory cases; leaves open broader applicability of SCN4A Arg222Trp findings.
Familial hypokalemic periodic paralysis is an autosomal-dominant channelopathy characterized by episodic muscle weakness with hypokalemia. The respiratory and cardiac muscles typically remain unaffected, but we report an atypical case of a family with hypokalemic periodic paralysis in which the affected members presented with frequent respiratory insufficiency during severe attacks. Molecular analysis revealed a heterozygous c.664 C>T transition in the sodium channel gene SCN4A, leading to an Arg222Trp mutation in the channel protein. The patients described here presented unusual clinical characteristics that included a severe respiratory phenotype, an incomplete penetrance in female carriers, and a different response to medications.
No takes yet. Share an insight, caveat, or question.
Park et al. (2010) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: