Homozygous Deletions of p l 6 / M T S l Gene Are Frequent But Mutations Are Infrequent in Childhood T - cell Acute Lymphoblastic Leukemia

Fifty-six primary childhood T-cell acute lymphoblastic leukemia (T-ALL) samples and 17 T-ALL cell lines were examined for mutations and homozygous deletions of the p l6 /MTSl gene using polymerase chain reaction single-strand conformation polymorphism and Southern blot analysis. Homozygous deletions were found in 22 primary samples (39%) and in 10 cell lines (59%). In contrast, mutations including small deletions and/or insertions were identified in only 4 primary samples (7%) and in 2 cell lines (12%). Mutations included one nonsense mutation at codon 72. one missense