Smith-Lemli-Opitz Syndrome

Test Description:

Smith-Lemli-Opitz Syndrome (SLOS) is caused by impaired cholesterol synthesis and results in congenital abnormalities including microcephaly, dysmorphic features, cleft palate, polydactyly and syndactyly, gastrointestinal anomalies and genital abnormalities in males. Intellectual deficits and behavioral problems, including autistic features, self-harm behaviors and hyperactivity may be present. The severity of symptoms may vary, with many children diagnosed at a very early age but some diagnosed later in childhood or adolescence. SLOS is caused by mutations in the gene DHCR7. While approximately 1 in 45 Caucasians are carriers for a DHCR7 mutation, SLOS is a comparatively rare disease, which may be due to a higher frequency of embryo losses early in pregnancy. Testing for fourteen mutations in this gene (c.964-1G&gtC, p.W151*, p.M1V, p.V326L, p.T93M, p.R352Q, p.R352W, p.R404C, p.S169L, p.R242C, p.R242H, p.F302L, p.G410S, and p.E448K) is expected to identify over 95% of carriers in the Ashkenazi Jewish population, where the carrier frequency is approximately 1 in 41.

Full gene sequencing is available for reproductive partners of known mutation carriers. Prenatal diagnosis is also available. Prior to ordering prenatal testing, please contact our laboratory at 212-241-7518 to discuss.


1. Witsch-Baumgartner M, Fitzky BU, Ogorelkova M, Kraft HG, Moebius FF, Glossmann H, Seedorf U, Gillessen-Kaesbach G, Hoffmann GF, Clayton P, Kelley RI, Utermann G. Mutational spectrum in the Delta7-sterol reductase gene and genotype-phenotype correlation in 84 patients with Smith-Lemli-Opitz syndrome. Am J Hum Genet. 2000 Feb66(2):402-12.

Specimen Requirements


Two 5-10 mL tubes of anticoagulated blood in EDTA (lavender top) or two 5-10 mL tubes of anticoagulated blood in ACD (yellow top).


Chorionic Villi: 5-10 mg in conical tube with sterile saline OR transport media
Amniotic Fluid: 10 ml in conical tube
Cultured Cells: Two confluent T-25 flasks

Additionally, please send:

5-10 ml maternal blood in EDTA (lavender top) required to perform MCC studies on all prenatal samples and in case maternal confirmation studies are necessary
5-10 ml paternal blood in EDTA (lavender top) in case paternal confirmation studies are necessary

Ordering Information


Ship at room temperature

Turnaround Time:

10 – 14 days

CPT Codes:


Forms and Brochures

Carrier Screening Requisition and Consent [PDF]
Expanded Ashkenazi Jewish Carrier Screening Brochure [PDF]
Ashkenazi Jewish Carrier Screening Panel