Background- SCN4A encodes the α-subunit of the skeletal muscle voltage-gated sodium channel (Na v 1.4). Several mutations, both in gain of function and loss of function, have been well described with various conditions including paramyotonia congenita, myotonia, periodic paralysis, congenital myasthenic syndromes, and congenital myopathies.1 There have been associations of the SCN4A gene and recurrent rhabdomyolysis; including one case report; however, recurrent rhabdomyolysis and paramyotonia congenita have not been described together .2-3 We present the case of a woman with both paramyotonia and recurrent rhabdomyolysis who was found to have two variants of uncertain significance in the SCN4A gene, at least one of which is likely pathological and associated with her presentation.
Case presentation- A 38-year-old woman presented with history of recurrent rhabdomyolysis following mild-to-moderate exercise beginning at the age of 28. She also had easy cramping and muscle stiffness early in exercise and with cold. Two variants in the SCNA4A genes were identified, one that is seemingly significant for both causes, c.2149 G>A (p.Val717Met).
Conclusion- The number of gene variants in SCN4A are vast, one possible rarely identified variant is now described in association with both recurrent rhabdomyolysis and paramyotonia congenita.