CONFIRMATION OF CHROMOSOME-9P LINKAGE IN FAMILIAL MELANOMA

Malignant melanoma occurs as a familial cancer in 5%-10% of cases wher e it segregates in a manner consistent with autosomal dominant inherit ance. Evidence from cytogenetics, fine-mapping studies of deletions in melanomas, and recent linkage studies supports the location of a huma n melanoma predisposition gene on the short arm of chromosome 9. We ha ve carried out linkage analysis using the 9p markers IFNA and D9S126 i n 26 Australian melanoma kindreds. Multipoint analysis gave a peak lod score of 4.43, 15 cM centromeric to D9S126, although a lod score of 4 .13 was also found 15 cM telomeric of IFNA. These data confirm the exi stence of a melanoma susceptibility gene on 9p and indicate that this locus most probably lies outside of the IFNA-D9S126 interval. No signi ficant heterogeneity was found between families, when either pairwise or multipoint data were analyzed using HOMOG.