Chronic lymphocytic leukemia is infrequent in Mexican mestizos.

Chronic lymphocytic leukemia (CLL) is the most frequent leukemia in adults living in Western countries, and accounts for approximately 30% of adult leukemias. In a 15-year period in a single institution, we identified 19 patients with CLL in a group of 211 adults with leukemia (9% of adult leukemias). Of these 19 CLL patients, 8 had a Caucasian phenotype, 4 were born outside the country, and only 11 were Mexican mestizos. On the other hand, in a multicenter experience involving 1968 Mexican adults with leukemia, CLL represented 6.6% of the cases, a figure significantly lower than that reported in Caucasians (P < 0.01). CLL is the least frequent type of leukemia in Mexican mestizos, and this low prevalence may stem from the genetic origin of this racial group. The data also suggest a genetic predisposition of Caucasians to suffer from this disease.