A clinical and genetic database for management of familial adenomatous polyposis.

Cachon-Gonzalez et al (7 Med Genet 1991;28:681-5) describe their experience with four linked DNA markers (x227, Cl ip 1, YN5.48, and ECB27) flanking the familial adenomatous polyposis (FAP) locus. They conclude that "lod scores are sufficiently high to allow the use of these probes in presymptomatic diagnosis". In the absence of large bowel adenomas or extracolonic manifestations of the FAP gene, a Bayesian approach to risk assessment, incorporating age of onset and DNA data, may guide clinical screening policy. We have developed a computerised regional register for FAP (called 'MegaBASE/FAP') which facilitates both risk assessment and coordination of screening examinations for the extended families of index patients. The core of the register software is the pedigree and this can be viewed on screen and printed out for use in the clinic. The main database contains information relating to administrative, screening, surgical, pathological, and genetic aspects of patient management, and this can be viewed and edited either on a text based screen or directly on the pedigree. From the genotypes stored on each family member, input files for the LINKAGE' programs can be written automatically within the database, which also contains a built in age of onset curve specified as 20 liability classes. The time consuming and error prone manual creation of LINKAGE files is thereby avoided, making risk evaluation both simpler and more reliable. Cachon-Gonzalez et al have suggested that closely linked markers might now be usefully incorporated in the modern management of FAP. By integrating clinical and genetic information our database has facilitated this development for families with FAP in our region.