Mitochondrial dysfunction in hyperkalemic periodic paralysis: A case report and literature review

Hyperkalemic periodic paralysis is a rare autosomal dominant disorder of sodium channels in skeletal muscles caused by pathogenic variants in the SCN4A gene. Emerging evidence suggests an association between this disorder and mitochondrial dysfunction, observed in mice. To our knowledge, there are still no reported cases demonstrating this link in humans.

We presented a case of hyperkalemic periodic paralysis caused by a heterozygous, de novo, and rare variant, NM_000334.4: c.2078T > C (p.Ile693Thr) in the SCN4A gene, reported for the first time in the Arab region. Our patient experienced intermittent episodes of weakness most frequently in the morning, with sudden onset of limb paralysis and inability to walk. She also exhibited facial myotonia with difficulty opening her mouth and eyelids. She was treated with preventive recommendations to avoid triggers and is now clinically stable. Additionally, the patient presented with mitochondrial dysfunction reported for the first time with hyperkalemic periodic paralysis.

This study is the first clinical report of mitochondrial respiratory chain enzymes dysfunction in a patient with hyperkalemic periodic paralysis caused by a rare variant, c.2078T > C (p.Ile693Thr), in the SCN4A gene.