The Birth Prevalence of Cleft Lip and Palate in Canadian Aboriginal Peoples

Sir:FigureStudies of the birth prevalence of orofacial clefts have demonstrated significant variation among ethnic groups, lending clues toward their genetic basis.1 Despite the indigenous peoples of North America having some of the highest rates of orofacial clefts in the world, there are few studies on this population, and most of them are limited by small sample sizes.2–5 We present a registry-based study to establish an accurate birth prevalence of orofacial clefts in a sample of indigenous peoples of North America. De-identified data were obtained from the Alberta Congenital Anomalies Surveillance System, which uses multiple sources for case ascertainment. All ascertained cases of cleft lip, cleft palate, and cleft lip and palate occurring in the Canadian Province of Alberta for the years 1994 to 2011 were included in the study. Both isolated cases and those with multiple congenital anomalies occurring in live births were included; stillbirths and induced abortions were excluded from the analysis. Because ethnicity is not recorded by Vital Statistics, personal healthcare numbers were cross-referenced to the Alberta Health Care Insurance Plan to determine aboriginal status (First Nations and Inuit peoples). Of 755,939 live births in Alberta over the study period, 50,400 had aboriginal status. The birth prevalence of orofacial clefts for both aboriginal and nonaboriginal individuals is shown in Table 1, along with counts and confidence intervals.Table 1: Prevalence of Orofacial Clefts per 1000 Live Births in Alberta, Canada, 1994 to 2011The prevalence rate of cleft lip with or without cleft palate is markedly higher in the aboriginal population than in the remainder of the population, consistent with older studies of other indigenous populations in North America. A population-based study in neighboring British Columbia found a cleft lip with or without cleft palate prevalence of 2.95 per 1000 live births between 1952 and 1971.2 A study in California from 1983 to 1992 indentified a cleft lip with or without cleft palate prevalence rate of 1.99 per 1000, including both live and stillbirths from a population-based registry.3 A survey of 46 designated hospitals in the United States found a cleft lip with or without cleft palate rate of 1.38 per 1000 live births for the years 1963 to 1966,4 and a statewide review in Montana reported a rate of 3.62 total clefts per 1000 births from 1955 to 1961.5 Investigations into the rate of orofacial clefts among different ethnic groups have demonstrated less variation in the rate of isolated cleft palate when compared with cleft lip with or without cleft palate, a finding reproduced in this study.1 There are several limitations of this small pilot study. First, the prevalence of orofacial clefts is likely underreported in the aboriginal group, as it does not include nontreaty or Métis individuals. As well, North America's population is increasingly diverse, which complicates comparisons among ethnic groups. Furthermore, indigenous peoples of North America are a heterogeneous group, so generalizations about predisposition should be made cautiously. This study is the largest of its kind in terms of sampling and reports one of the highest rates of cleft lip with or without cleft palate in North America among the population-level studies. This update to the literature serves as a tool for plastic surgeons counseling aboriginal patients, and can better direct investigations into the etiology of orofacial clefts. Sebastian Q. Vrouwe, B.Sc. Division of Plastic Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada R. Brian Lowry, M.D., D.Sc. Departments of Medical Genetics and Pediatrics, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada Jaret L. Olson, M.D. Gordon H. Wilkes, M.D. Division of Plastic Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada ACKNOWLEDGMENT The authors acknowledge Michael Sanderson for his assistance with the data release. DISCLAIMER This study is based in part on data provided by Alberta Health. The interpretation and conclusions contained herein are those of the authors and do not necessarily represent the views of the government of Alberta. Neither the government nor Alberta Health expresses any opinion in relation to this study. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. The authors received no external funding for this study.

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