Screening for multiple endocrine neoplasia type 2a with DNA-polymorphism analysis.

Multiple endocrine neoplasia type 2a has been shown to be genetically linked to a locus near the centromere of chromosome 10. The availability of polymorphic DNA probes for the region permits the use of restriction-fragment-length polymorphisms (RFLP) to identify carriers of the gene for this cancer syndrome. As part of a French national program, DNA probes were used in a genetic-linkage study of 130 members of 11 families of European and North African origin. In these families there was no recombination between the mutation causing multiple endocrine neoplasia type 2a and two of the three probes used. All 11 families were informative for at least one of the three markers, and linkage information was adequate to provide genetic counseling to 8 families. We found that RFLP analysis is much more useful in predicting the carrier state than conventional endocrine challenge, especially in younger people, but accuracy is maximal when both methods are employed. We conclude that genetic screening allows the identification of those who are at risk for multiple endocrine neoplasia type 2a at any age with a high level of certainty. After initial screening with DNA, tests for early neoplastic change may be directed toward those determined to be at high risk.