Cell Current Biology 30: P3465-69. These alterations were found in a Neanderthal version of a gene, the
SCN9A gene, that encodes Nav1.7 voltage-gated sodium ion channel involved in nerve transmission in peripheral nerves and implicated in pain sensation. In modern humans, mutations in this gene causing a loss of function phenotype (inactivation of this gene) are associated with pain insensitivity and anosmia, while gain of function mutations (increased activity) are associated with idiopathic small-fiber neuropathy and increased sensitivity to pain.
The Neanderthal-specific alleles reported in this paper contained three amino acid variants (M932L, V991L, and D1908G) compared with the gene found in modern humans; alleles containing all three of these variant amino acids are not found in any living primate other than humans (