130 KB OF DNA-SEQUENCE REVEALS 2 NEW GENES AND A REGIONAL DUPLICATIONDISTAL TO THE HUMAN IDURONATE-2-SULFATE SULFATASE LOCUS

Deficiency of IDS activity results in Hunter Syndrome [mucopolysacchar idosis type II], a fatal X-linked recessive disorder. We report charac terization of 28 cosmids around the IDS locus in Xq28. Four overlappin g cosmids have been sequenced in their entirety generating a 130-kb co ntig. These studies show the fine structure of the IDS gene and identi fy an IDS pseudogene-like structure located 20 kb distal to the active gene. Two novel genes have also been identified in this sequence, and one of these genes is also locally duplicated. Both homologs are expr essed, and a number of alternative transcript products have been chara cterized. The presence of a highly conserved pseudogene-like structure within a larger duplicated region close to the IDS gene has significa nt implications for the study of mutations at this locus.