Smith-Lemli-Opitz Syndrome

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessively inherited multiple malformation syndrome due to an inborn error cholesterol synthesis – insufficiency of enzyme 7-dehydroxycholesterol reductase. The syndrome is characterized by intrauterine and also postnatal growth retardation, moderate to severe mental retardation, malformations in many organ systems (cardiovascular, urogenital, gastrointestinal and central nervous systems). The patients have a characteristic appearance: ptosis, polydactyly, syndactyly of the II and III toes on both feet.

The incidence of SLOS is 1:20,000-70,000. SLOS is associated with mutations in the DHCR7 gene.


> Ordering information for DHCR7 gene sequencing


Indications for genetic testing:

1. Confirmation of clinical diagnosis
2. Carrier testing for at-risk family members
3. Genetic counseling
4. Prenatal diagnosis for known familial mutation


For further information:

Genetic assessment following increased nuchal translucency and normal karyotype
Pergament E, Alamillo C, Sak K, Fiddler M.
Prenat Diagn. 2011 Mar;31(3):307-10. doi: 10.1002/pd.2718. Epub 2011 Feb 15.