SLC16A2 and Intellectual disability: Causative mutations in the SLC16A2 (solute carrier family 16, member 2) gene on Xq13.8 have now been identified in more than 170 males from 90 families and some heterozygote carrriers,39,40 and probably also accounts for a proportion of adult males with unresolved X-linked intellectual disability.21SLC16A2 belongs to the 14 members of the SLC16 family of genes41 and encodes the MCT8 protein.