Esterase D assay in Brazilian retinoblastoma families.

The gene related to retinoblastoma (Rb gene) can be considered a model human tumor suppressor gene and was assigned to band 13q14, together with the esterase D (ESD) gene. We studied the ESD activity and phenotype in 40 retinoblastoma patients, 50 unaffected relatives, and 85 nonrelated healthy control individuals. ESD activity from patients is significantly different from that of relatives and control individuals, but there was no significant difference between ESD activity from unaffected relatives and control individuals. Twelve and one-half percent of patients and 4.2% of unaffected relatives with ESD1 phenotype showed a low ESD level. The results showed the importance of ESD studies in all retinoblastoma patients and their relatives.