Hypokalaemic periodic paralysis due to the CACNA1S R1239H mutation in a large African family

Hypokalaemic periodic paralysis (HypoKPP) is a skeletal muscle channelopathy caused by mutations in calcium (CACNA1S) and sodium (SCN4A) channel subunits. A small number of causative mutations have been found in European and Asian patients, but not in African patients yet. We have identified a large Beninese family in which HypoKPP segregated over five generations and was caused by the CACNA1S R1239H mutation. We report on the clinical and histopathological spectrum of the disorder in this family. A later age at onset (15.8 ± 8.8 years), and particular triggering factors due to specific African life conditions seem to be characteristic of our observation.