Updating the Epidemiology of Isolated Cleft Palate

Sir: The report by Tanaka et al.1 on the epidemiology of isolated cleft palate raises several issues, the first one being the use of the term “isolated.” It would appear that the authors mean isolated with respect to the absence of a cleft lip, whereas to most workers in the field the term isolated means no other malformation, syndrome, sequence, or cytogenetic abnormality in association with cleft palate. Other issues include the fact that no sources are given for the data in their table, the lumping together of countries, and the short study term of 5 years. From the rates supplied, it would appear that the authors do not report truly isolated cleft palate but include cleft palate with multiple anomalies, syndromes, sequences, and cytogenetic abnormalities. It appears that the international data were taken from the 2008 Annual Report from the International Clearinghouse for Birth Defects, Surveillance and Research, which has a data column for 2002 to 2006, corresponding to Tanaka et al.’s study years. Many countries, including the United States, do not have a single national system. Those with highly reliable national systems are smaller countries with a long history of public health programs, particularly in Europe and especially the Nordic countries, whereas countries such as Canada, Australia, and England are better served by provincial, state, or regional surveillance registries. It is not clear how the authors derived rates for France or Italy, as each country has four or more surveillance registries. Finally, we suggest that a 5-year study is too short for inferring that the rates of cleft palate are increasing. In Alberta, using data for the 1997 to 2010 period, the cleft palate rate is 7.09 per 1000 total births (6.43 to 7.81) and is showing a decline not only for those without additional anomalies (true isolated) but also for those with multiple anomalies. The rates for those with syndromes remain stable (Fig. 1). The Alberta rate is very similar to two earlier long-term studies from British Columbia for 1952 to 19712 and 1952 to 1982.3 Other areas with long-term studies have shown no significant trend for cleft palate: The Netherlands from 1997 to 20064 and Victoria, Australia from 1983 to 2000.5Fig. 1: Cleft palate alone, Alberta 1997 to 2009. Total, isolated, multiple, and syndromes (including recognized syndromes and chromosomal abnormalities). (From Alberta Health and Wellness. Alberta Congenital Anomalies Surveillance System: Ninth Report 1997–2009. Edmonton, Alberta, Canada: Alberta Health and Wellness; 2012. Available at: http://www.health.alberta.ca/documents/Congenital-Anomalies-Report-8-2009.pdf.)ACKNOWLEDGMENTS The authors thank Judy Anderson and Tanya Bedard for manuscript assistance, and they are thankful for the support of Michael Sanderson and Larry Svenson from Alberta Health. The Alberta Congenital Anomalies Surveillance System is supported by the Surveillance Branch, Alberta Health and Wellness. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. R. Brian Lowry, M.D., D.Sc. Alberta Congenital Anomalies Surveillance System Alberta Health, and Departments of Medical Genetics and Pediatrics University of Calgary and Alberta Children’s Hospital Research Institute Barbara Sibbald, B.N., M.Sc. Alberta Congenital Anomalies Surveillance System Alberta Health Calgary, Alberta, Canada

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