Genetic study of phenylketonuria

Among four hundred and eighty mentally retarded patients referred to the Human Genetics clinic, Medical Research Institute, Alexandria University, Egypt; twelve cases were found to have pku, ten cases had classical pku and 2 cases atypical pku. Genetic studies of those patients and their families revealed segregation of autosomal gene(s) that are responsible for the development of the disorder with a recurrence risk of 0.283 +/- (1.96)(0.066). The high average inbreeding Coefficient indicated the important role played by consanguinity. Heterozygote detection is very important to normal sibs of affected patients to provide proper genetic counseling. Dietary management of the young infants in the first three months showed normal growth and development. Behavioral improvement was observed in cases who were treated late despite the fact that they were mentally retarded. Dietary control should be continued for a long life time to obtain good outcome in both sexes and to prevent the risk of fetal damage during child-bearing age in females.