Physical mapping of the human ATX1 homologue (HAH1) to the critical regionof the 5q-syndrome within 5q32, and immediately adjacent to the SPARC gene

The 5q- syndrome is a myelodysplastic syndrome with the 5q deletion as the sole karyotypic abnormality. The human ATX1 homologue (HAH1), encodes a cop per-binding protein with a role in antioxidant defence. We have mapped this gene to the 3 Mb critical region of gene loss of the 5q- syndrome within 5 q32, flanked by the genes for ADRB2 and IL12B, using gene dosage analysis. Fine physical mapping of the HAH1 gene within this genomic interval was the n performed by screening YAC and BAC contigs spanning the critical region o f the 5q- syndrome using PCR amplification. The HAH1 gene maps immediately adjacent to the SPARC gene at 5q32, and is flanked by the genetic markers D 5S1838 and D5S1419. The HAH1 gene is expressed in haematological tissues an d plays a role in antioxidant defence. Antioxidant levels are low in most c ancers and the importance of antioxidant enzymes in cancer genesis is well recognised. Genomic localisation, function and expression would suggest tha t the HAH1 gene represents a candidate gene for the 5q-syndrome,