CACNA2D4 variants are associated with exertional heat stroke susceptibility
Exertional Heat Stroke (EHS) is a life-threatening disease defined by severe hyperthermia and sudden neurological dysfunction in healthy individuals exposed to intense physical exercise. As is the case with some forms of malignant hyperthermia, mutations in genes involved in skeletal muscle contraction could predispose some patients to EHS. However, the genetic basis of EHS remains poorly documented. Here we identify EHS-associated variants in the CACNA2D4 gene encoding the Cav Ca2+ channel subunit, 2{delta}4, and describe their impact in heterologous expression systems and a knock-in mutant mouse strain heterozygous for the S299R variant (S299R+/-). In transfected cells, each CACNA2D4 variant, including S299R, affected the trafficking and function of 2{delta}4 and its regulation of the Cav1.1 channel. S299R+/-mice showed EHS-like crisis with signs of rhabdomyolysis and an elevation in core body temperature when submitted to an intense exercise protocol. We show that a CACNA2D4 transcript is expressed in mouse skeletal muscle and that the presence of the S299R variant in 2{delta}4 induces a modification in the calcium flux triggered by muscle cell depolarization. Altogether, our data reveal an unexpected connection between CACNA2D4 gene variants and pathophysiological alterations in skeletal muscle Ca2+ signaling that may increase EHS susceptibility.