Smith-Lemli-Opitz Syndrome (SLOS)

Epidemiology and Etiology:

· Abnormality in cholesterol metabolism

· Deficiency in the enzyme 7-dehyrdrocholesterol (7-DHC) reductase

· Autosomal recessive

Common sites:

·

Gross features:

· (wide clinical spectrum)

· Growth retardation (pre and post-natal)

· Microcephaly

· Dysmorphic facies

· Cleft palate

· Cardiac defects

· Pyloric stenosis

· Underdeveloped external genitalia in males

· hypospadias

· Postaxial polydactyly

· 2,3 syndactyly of the toes

Histologic features:

·

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

· DHCR7 mutations

· Sequence analysis detects ~96% of known mutations

Other features:

· Mental retardation (moderate to severe)

· Serum 7-DHC elevated

· Serum cholesterol low or normal

References:

· GeneReviews (2007)