Prenatal diagnosis of single gene disorders in northern Finland.

Prenatal diagnosis of single gene disorders is challenging because of the multidisciplinary diagnostic approach and the genetic counselling needed. Out of 3100 pregnancies of northern Finnish women studied for early detection of congenital defects or genetic disease, 110 were at risk for and 15 were unexpectedly found to carry a fetus with a single gene disorder. Seven of the 21 diseases studied were typically representative of inherited diseases in northern Finland. The diagnostic approaches used included fetal ultrasonography, analysis of the components of the amniotic fluid, fetal enzyme analysis, fetal karyotyping for the fragile X syndrome, and fetal DNA analysis. Altogether, 50 pregnancies were found to be affected; 11 of these were continued because the diagnosis was too late for termination, and seven because the parents wanted it. Prenatal diagnosis of severe hereditary disease can be enhanced by improving the detection of pregnancies at risk, and by developing methods for earlier fetal diagnosis.