Simpson-Golabi-Behmel syndrome: disproportionate fetal overgrowth and elevated maternal serum alpha-fetoprotein.

Simpson-Golabi-Behmel (SGB) syndrome is an X-linked condition with pre- and postnatal overgrowth, characteristic facies, and visceral and skeletal anomalies. We report an affected male who presented at 16 weeks' gestation with elevated maternal serum alpha-fetoprotein (MSAFP). Fetal measurements at 20 and 31 weeks' gestation were disproportionate, with marked macrosomia but a low head to abdominal circumference ratio and normal femur length. Fetal overgrowth with elevated MSAFP may prove to be useful markers for the prenatal diagnosis of SGB syndrome.