Table  2.   Three structurally related human genes with an anion transport function and mutations in distinct diseases


Gene Chromosomal Location Structural Information Site of Expression Transported Anions Disease Caused by Mutations Number of Known Mutations

CLD (DRA) 7q22-q31.1 21 exons, 764 aa Differentiated cells in ileal and colonic mucosa, prostate Sulfate, oxalate, chloride, others? CLD 20
PDS 7q22-q31.1 21 exons, 780 aa Thyroid, other? Not known Pendred syndrome 15
DTDST 5q32-q33.1 4 exons, 739 aa Many tissues, more in cartilage and ileum Sulfate, chloride, others? Diastrophic dysplasia, congenital achondrogenesis type IB, atelosteogenesis type II 14

aa, Amino acids; DRA, downregulated in adenoma gene; PDS, putative sulfate transporter gene; DTDST, diastrophic dysplasia gene.