THE GIST SCORE - RANKING GLAUCOMA FOR GENETIC-STUDIES

The 'GIST' score was developed to facilitate linkage analysis of adult -onset primary open angle glaucoma (POAG) pedigrees in the Glaucoma In heritance Study of Tasmania (GIST). Previous genetic linkage studies o n juvenile open angle glaucoma pedigrees have relied upon an analysis of definitely affected individuals using the 'single best diagnosis' c onvention. Studies of adult-onset POAG have been complicated by limite d numbers of unequivocally affected members identified even in very la rge pedigrees due to the later onset of the disease. Many members of t he pedigree may have equivocal clinical features or are too young to s how signs of the disease. The 'GIST score' is a numeric value between zero and one where zero is clinical certainty of absence of the diseas e and one is the definitive diagnosis of POAG. The score is developed by assigning relative weighting to key clinical features which results in a 'pedigee probability' of the diagnosis being present or absent i n a member of a pedigree. Ranking of borderline and unaffected glaucom a subjects allows the laboratory more flexibility in the use of the me mbers of the pedigree for linkage analysis. The score is not intended to have clinical usefulness in management of glaucoma.