A REFINED LOCALIZATION OF 2 DELETED REGIONS IN CHROMOSOME 6Q ASSOCIATED WITH SALIVARY-GLAND CARCINOMAS

Deletions within chromosome 6 (6q25 to 6qter) are the most consistent structural change observed in salivary gland carcinomas, To better def ine the location of these deletions we investigated loss of heterozygo sity (LOH) for 23 polymorphic markers within 19 salivary gland carcino mas covering several histological subtypes, LOH was observed in 47% of tumors, confirming previous reports that such losses are frequent and occur in almost all histological subtypes of tumors, The highest freq uency of LOH was found at, or distal to, D6S437, Seven tumors had alle lic losses for D6S297 and/or D6S37, A second peak of loss was also obs erved at D6S262 and D6S32, In some tumors we observed LOH in one or th e other of these two regions, In other tumors we observed loss of both regions with retention of intervening loci, These data suggest that t wo small deletions commonly occur, one between D6S262 and D6S32 (estim ated to cover less than 1.5 Mb) and another between D6S297 and D6S446 (estimated to cover similar to 2 Mb), These results extend previous st udies by sublocalizing the regions of LOH and suggest that inactivatio n of one or more tumor suppressor genes located in these regions may b e an important step in salivary gland carcinogenesis.