LOSS OF HETEROZYGOSITY AND HOMOZYGOUS DELETIONS ON 9P21-22 IN MELANOMA

Recent studies have implicated chromosome 9p21-22 as a location for a gene involved in cutaneous melanoma (CM). Deletion mapping in 35 match ed tumour-constitutional DNA pairs from metastatic melanomas (includin g one melanoma cell line) and one dysplastic naevus has been performed using six short tandem repeat polymorphic (STRP) markers (D9S157-D9S1 62-LFNA-D9S171-D9S126-D9S104) which span approximately 19 cM across th e 9p21-22 region. Both heterozygous and homozygous deletions were obse rved across the region in melanomas from both sporadic and familial ca ses. Overall 57% (20/35) of the samples displayed some form of loss. A deletion map identifies two areas of common loss either side of the i nterferon gene cluster. Familial CM has previously been shown to link to the more proximal of these regions. The deleted region distal to IF NA has not been previously described in melanoma. The results imply th e involvement of more than one tumour suppressor gene on 9p in CM.