NEURAL-TUBE DEFECTS ALPHA-FETOPROTEIN/DOWNS-SYNDROME SCREENING/

Maternal serum screening for alpha-fetoprotein, initially as an indica tor of open neural tube defects and more recently combined with other pregnancy-specific markers as an indicator of Down's syndrome, is an e stablished part of prenatal testing. Recent work has focused on the ro le of folic acid in the primary prevention of neural tube defects and on the search for a genetic component in the aetiology of neural tube defects. Potential new markers of Down's syndrome have been identified in maternal serum and urine, Nuchal translucency measurements by ultr asound and the identification of appropriate maternal serum markers in the first trimester offer the prospect of screening earlier in pregna ncy.