Genotype-phenotype correlations in L1 syndrome: a guide for genetic counselling and mutation analysis.

Objectives: To develop a comprehensive mutation analysis system with a high rate of detection, to develop a tool to predict the chance of detecting a mutation in the L1CAM gene, and to look for genotype-phenotype correlations in the X-linked recessive disorder, L1 syndrome.

Methods: DNA from 367 referred patients was analysed for mutations in the coding sequences of the gene. A subgroup of 100 patients was also investigated for mutations in regulatory sequences and for large duplications.

[Familial colorectal cancer].

The most frequent monogenic predisposition to CRC is hereditary non-polyposis colorectal cancer (HNPCC). Less frequent are syndromes with polyposis. In some families the occurrence of CRC indicates a familial risk of CRC without the diagnostic criteria for the above syndromes being fulfilled.