rs1815739
rs1815739 is the ACTN3 R577X variant, a C>T nonsense mutation in exon 16 that converts an arginine codon to a premature stop codon at position 577. The X (T) allele abolishes production of functional alpha-actinin-3, a structural protein found only in fast-twitch (type II) muscle fibers, so XX homozygotes make none of the protein while RR homozygotes make it normally. This underlies its widely studied association with power/sprint versus endurance muscle-fiber tendencies.
Traits rs1815739 reads
Gene
Reference databases
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