[MIM 270 400]

Prevalence: 1/20,000 to 1/60,000. Autosomal recessive transmission of mutations of the DHCR7 gene on 11 q 12-13. This mutation produces a deficiency in 7-dehydrocholesterol reductase that causes a disturbance in the synthesis of cholesterol: low plasma cholesterol. The absence of endogenous cholesterol  synthesis during fetal life results in intrauterine growth retardation and a polymalformative syndrome. Two types, (classic) I and II (severe, with significant perinatal mortality).

Characteristics:

-        growth retardation

-        microcephaly with cerebral malformations: lissencephaly, hydrocephalus, agenesis of the corpus callosum

-        facial dysmorphism: micrognathia, cleft palate, small hard tongue, downslanting palpebral fissures, ptosis, narrow forehead

-        cardiac malformation

-        abnormalities of the extremities (syndactyly)

-        abnormalities of the external genitalia: hypospadias, sexual ambiguity

-        aggressive behaviour and self-harm.

Sometimes: pyloric stenosis, Hirchsprung disease, vesicoureteral reflux.

Anesthetic implications:

difficult intubation. Gastroesophageal reflux disease. Start intubation with an endotracheal tube the size of which is smaller than expected for age. Two cases have been published with muscle rigidity after administration of halothane but no risk of malignant hyperthermia.

References : 

• Choi PT, Nowaczyk MJ. 
  Anesthetic considerations in Smith-Lemli-Opitz syndrome. 
  Can J Anaesth 2000; 47:556-61.
• Quezado ZMN, Veihmeyer J, Schwartz L, Nwokoro NA, Porter FD. 
  Anesthesia and airway management of pediatric patients with Smith-Lemli- Opitz syndrome. 
  Anesthesiology 2002; 97: 1015-9.
• Petersen WC, Crouch ER. 
  Anesthesia-induced rigidity, unrelated to succinylcholine, associated with Smith-Lemli-Opitz syndrome and malignant hyperthermia. 
  Anesth Analg 1995; 80:606-8.

Updated: September 2018