A patient may be suspected of having the Smith-Lemli-Optiz Syndrome based on a constellation of physical findings, with confirmation by identifying an increase in plasma or serum 7-dehydrocholesterol (7DHC). The underlying defect is a deficiency in the enzyme 7DHC reductase (7DHCR).


Inheritance: autosomal recessive


Clinical findings:

(1) growth deficiency with prenatal onset (small at birth)

(2) developmental delay or mental retardation

(3) facial appearance (below)

(4) cleft palate

(5) cardiac defects

(6) hypospadias in males

(7) polydactyly

(8) syndactyly of second and third toes


Characteristic facial appearance (best seen as a small child, may not be readily apparent in the adult):

(1) narrow bifrontal diameter

(2) ptosis

(3) downward slanting palpebral fissures

(4) short nose with depressed nasal bridge and anteverted nares

(5) low set ears, posteriorly rotated

(6) retrognathia

(7) smooth appearing philtrum


Diagnosis depends on demonstration of elevated 7DHC (7-dehydrocholesterol) levels in plasma.


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