Prenatal diagnosis and fetal therapy--what lies in future?

Abstract

Prenatal diagnosis has traditionally occurred between the 15th and 20th weeks of gestation. However, the capabilities of screening and diagnostic tools have advanced substantially over the past 10 years. Recent advances in the science of prenatal diagnosis allow for the evaluation of an affected embryo or an abnormal cell line prior to gestation within the womb via preimplantation diagnosis. The technique can be used for any genetic condition which can be detected with a chromosome-specific probe. At the current time, noninvasive second trimester maternal serum screening with either 2 or 3 serum analytes is associated with a 60-70% detection rate of Down syndrome. Although these particular serum markers are not useful during the first trimester, the fetoplacental secretory products-free beta-hCG and pregnancy-associated plasma protein-A (PAPP-A) appear to be meaningful clinically when measured between 8 and 13 weeks of gestation, yielding similar first trimester detection rates as the current second trimester screening programme. The addition of nuchal translucency measurements as an independent predictor of fetal aneuploidy may further increase the detection rate of Down syndrome to 80%. Open fetal surgery is now possible under highly selective circumstances in which the fetal condition is considered life-threatening and the prognosis is extremely poor. Surgical intervention may be appropriate for congenital cystic adenomatoid malformation, bronchopulmonary sequestration, congenital diaphragmatic hernia, and possibly for myelomeningocele.