Aberrant nuclear p53 expression predicts hemizygous 17p (TP53) deletion in chronic lymphocytic leukemia.

Hemizygous TP53 gene deletion is the most important adverse risk factor in chronic lymphocytic leukemia (CLL), but its relationship with p53 protein expression is unclear. We investigated 110 CLL cases and correlated nuclear p53 protein immunoreactivity with TP53 gene deletion status and other CLL-associated genetic risk factors. Fluorescence in situ hybridization detected hemizygous TP53 deletions in 15 cases (13.6%), whereas immunohistochemical analysis detected nuclear p53 protein expression in 14 (12.7%). All cases expressing nuclear p53 protein had hemizygous TP53 deletions. Hemizygous TP53 gene deletion and p53 protein expression were strongly correlated (P < .001). There was no association between p53 expression and del(13q), del(11q) or trisomy 12 in CLL cases. Our data indicate that nuclear p53 protein expression, detected by a widely available immunohistochemical method, is strongly associated with TP53 deletion and that p53 immunohistochemical analysis may be adopted as a rapid, robust diagnostic tool for risk stratification of CLL.