Incidence of Smith-Lemli-Opitz syndrome in Canada: results of three-year population surveillance.
OBJECTIVE
To determine the incidence and point prevalence of Smith-Lemli-Opitz syndrome (SLOS) in Canada; to determine the percentage of mild cases of SLOS; and to determine the age of diagnosis of mildly affected patients. SLOS is a treatable genetic condition that may be difficult to diagnose in its mildest form because of nonspecific clinical markers (two- to three-toe webbing, short upturned nose, and micrognathia).


METHODS
More than 2000 Canadian pediatricians and pediatric specialists were surveyed monthly for 36 months through a standing national surveillance program. A clinical identification form was designed to identify patients with SLOS or its phenocopies. Clinical information was obtained on all reported cases; suggested cases were investigated by biochemical or molecular analysis.


RESULTS
Thirty-five of 86 reports of suggested SLOS were confirmed SLOS. Twelve infants with SLOS were born during the surveillance period, and two additional infants with SLOS were diagnosed prenatally. Twenty-one infants with SLOS were born before the onset of surveillance.


CONCLUSIONS
The minimum incidence of SLOS in Canada is 1 in 70,358 live births. The minimum prevalence of SLOS is approximately 1 in 950,000. Eighteen percent of patients were mildly affected; the mean age of diagnosis of mildly affected patients was 5.3 years.
Nowaczyk
Małgorzata J M
MJ
Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada. nowaczyk@hhsc.ca <nowaczyk@hhsc.ca>
Zeesman
Susan
S
Waye
John S
JS
Douketis
James D
JD
D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D011159:Population Surveillance; D015995:Prevalence; D011446:Prospective Studies; D019082:Smith-Lemli-Opitz Syndrome / Q000453:epidemiology*; D044465:White People / Q000706:statistics & numerical data