THE ROLE OF MOLECULAR-GENETICS IN THE PRENATAL-DIAGNOSIS OF RETINAL DYSTROPHIES

Inherited retinal dystrophies are important causes of incurable blindn ess in developed countries, Advances in molecular genetics promise sig nificant improvements in their management. Immediate benefits of prese nt knowledge are presymptomatic and prenatal diagnosis in selected cas es, To study the predictive power of these techniques a simulated gene tic risk estimation was undertaken in a cone-rod retinal dystrophy ped igree known to be linked to chromosome 19. Using data on five fully in formative, flanking DNA markers, phenotype was correctly assigned with only a 2% probability of error, If the two most closely linked marker s were found to be uninformative, this error probability remained unch anged, Using genetic risk calculations and direct mutation detection m any retinal dystrophies could now be identified by prenatal diagnosis.