Smith-Lemli-Opitz syndrome (SLOS) is a multiple congenital anomalies/mental retardation (MCA/MR) syndrome. It is a rare autosomal recessive disorder of cholesterol metabolism where in the conversion of 7 dehydrocholesterol (7-DHC) into cholesterol is disrupted leading to excessive accumulations of 7- DHC, 8-DHC and cholesterol deficiency. Mutations in the DHCR7 gene are responsible for SLOS. Spontaneous abortion, congenital heart diseases, death due to multiorgan failure in 1st week, failure to thrive, vomiting, constipation, hearing and visual loss may be present. Diagnosis is based on clinical and biochemical profile like low cholesterol and absent LDL cholesterol, karyotype and Ultrasound abdomen.

Cholesterol replacement forms the cornerstone in medical management and coexisting surgical condition may need appropriate evaluation and intervention.

Prenatal diagnosis by fetal ultrasound may revel multiple congenital anomalies, increased 7-DHC and mutation analysis in amniotic fluid or chorionic venous sampling, decrease maternal serum unconjugated estriol or other marker for triple test with normal karyotype. The unique presence of equine estriols in the maternal urine during pregnancy of a fetus affected by SLOS, potentially allows noninvasive prenatal screening for SLOS.

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Last updated on: 1-07-2008 Vol 5 Issue 7 Art # 28

Advance Access on: 15-08-2007

Vaghela PC, Gohel N, Mehta S. Smith- Lemli Opitz Syndrome. Pediatric Oncall [serial online] 2008 [cited 2008 July 1];5. Art # 28. Available from:
http://www.pediatriconcall.com/fordoctor/viewersChoice/opitz_syndrome.asp

Advance Access: 15th August 2007