A plethora of human diseases are associated with mutations in the genes encoding human SLC26 transporters, including chondrodysplasias with varying severity in SLC26A2 (~50 mutations, 27 point mutations), congenital chloride-losing diarrhea in SLC26A3 (~70 mutations, 31 point mutations) and Pendred Syndrome or deafness autosomal recessive type 4 in SLC26A4 (~500 mutations, 203 point mutations).
Special interest has focused on four members of the SLC26 family that are associated with distinct recessive diseases: (i) Mutations in SLC26A2 lead to four different chondrodysplasias (diastrophic dysplasia, atelosteogenesis type II, achondrogenesis type IB and multiple epiphyseal dysplasia); (ii) SLC26A3 is associated with congenital chloride diarrhea; (iii) SLC26A4 is associated with Pendred syndrome and non-syndromic deafness, DFNB4; and (iv) SLC26A5 is defective in non-syndromic hearing impairment.
Genomic sequencing of a BAC clone H_RG364P16 revealed the presence of another, highly homologous gene 3' of the CLD gene, with a similar genomic structure, recently identified as the Pendred syndrome gene (PDS).