Difficulties in recognizing families with Hereditary Non-polyposis Colorectal Carcinoma. Presentation of 4 families with proven mutation.

INTRODUCTION: Hereditary Non-polyposis Colorectal Carcinoma is the most frequent genetic disease leading to colon and other malignancies. Recognizing the condition requires extensive family history going back several generations focusing particularly on the types of tumors occurring in the family at different age groups. METHODS: In families who met the Amsterdam and Bethesda Criteria, the removed tumor tissue was first examined by immunohistochemistry and microsatellite instability analysis. Subsequently DNA sequencing was performed to detect an underlying Mismatch Repair Gene mutation and multiple ligation dependent probe amplification was applied for recognizing large deletions in Mismatch Repair Genes. RESULTS: In the investigated families 3 pathogen mutations, 1 large deletion and 2 cases of polymorphism were found. There is considerable difference between the families in terms of the types of malignancies and the age in which those appeared. CONCLUSION: Recognizing families with Hereditary Non-polyposis Colorectal Carcinoma presents great difficulties because of the variety of phenotypes in presentation. Special attention should be paid to small families and those who present with cancer of other than colon origin. Practicing physicians should be made aware of the fact that this disease may have atypical presentations. Follow up of families who have already been screened may be difficult for social, economical or religious reasons.

Synergistic interaction of ABCB1 and ABCG2 polymorphisms predicts the prevalence of toxic encephalopathy during anticancer chemotherapy.

Polymorphisms of the ABCB1 (MDR1) and ABCG2 (BCRP) genes were reported to alter the expression and function of these drug transporters. Both proteins are present at the main pharmacokinetic barriers including the blood-brain barrier. Data from 291 children with acute lymphoblastic leukaemia were analysed in this retrospective study. ABCB1 3435T>C, 2677G>T/A, 1236C>T and ABCG2 421C>A, 34G>A genotypes were determined. Encephalopathy episodes were more frequent among those with ABCB1 3435TT genotype than in the 3435CC/CT group (odds ratio (OR) 3.5; P=0.03). Patients with the ABCG2 421A allele tended to have more complications than wild type homozygotes (OR=2.0; P=0.25). The rate of the adverse effect was similar in those harbouring no or only one of the predisposing genotypes, that is, either ABCB1 3435TT or ABCG2 421AA/AC. However, significantly more children suffered encephalopathy in the group with both predisposing genotypes (OR=12.3; P=0.005). In conclusion, these variations exert synergistic effect in predisposing patients to toxic neurological complications of chemotherapy.