Prenatal diagnosis of Smith-Lemli-Opitz syndrome is possible by measurement of 7-dehydrocholesterol in amniotic fluid.
Amniocentesis was performed at 17.3 weeks in a pregnancy with severe intrauterine growth retardation. Cytogenetic studies on amniocytes were normal, 46,XX, and the pregnancy was continued. The diagnosis of Smith-Lemli-Opitz syndrome was suspected in the neonatal period and confirmed by the presence of 7-dehydrocholesterol (7-DHC) in the plasma (0.4 mmol/l, normal = not detectable) associated with a low total cholesterol concentration (0.4 mmol/l, normal = 2.56 +/- 0.23). Retrospective analysis of the amniotic fluid sample revealed an elevated level of 7-DHC (0.022 mmol/l; normal = undetectable). Therefore measurement of 7-DHC levels in amniotic fluid during the second trimester of pregnancy is useful for the prenatal diagnosis of Smith-Lemli-Opitz syndrome in families at risk and should be considered in cases of severe growth retardation of unknown aetiology for which amniotic fluid is available and in which a normal chromosomal pattern in amniocytes is present.
Dallaire
L
L
Service de Génétique Médicale, Hôpital Sainte-Justine, Montreal, Québec, Canada.
Mitchell
G
G
Giguère
R
R
Lefebvre
F
F
Melançon
S B
SB
Lambert
M
M
D000328:Adult; D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry*; D002784:Cholesterol / Q000097:blood; D002849:Chromatography, Gas; D003684:Dehydrocholesterols / Q000032:analysis* / Q000097:blood; D005260:Female; D005317:Fetal Growth Retardation / Q000209:etiology; D006801:Humans; D013058:Mass Spectrometry; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D019082:Smith-Lemli-Opitz Syndrome / Q000175:diagnosis* / Q000378:metabolism
D003684:Dehydrocholesterols; D002784:Cholesterol; C016705:7-dehydrocholesterol