Congenital anomalies in children with acute lymphoblastic leukaemia and in their family

Background. With the exception of Down syndrome the association between congenital anomalies and acute lymphoblastic leukaemia (ALL) is presently unclear. We investigated this association in a population-based case-control study carried out in the province of Québec, Canada. Methods. A total of 491 incident cases diagnosed between 1980 and 1993 and aged 0-9 years were included in the study. Healthy controls (n=491) matched on age, sex, and region of residence at the time of diagnosis were selected from government family allowance files. Using a structured questionnaire and the International Classification of Diseases (Ninth Revision) list of congenital anomalies, presence of an anomaly was determined by interviewing the parents of the study subjects; mothers gave information on anomalies in the study subject, their siblings and her family, whereas fathers provided information on anomalies in their family. Results. The adjusted risk for ALL was not increased in children who had any anomaly (odds ratio [OR] = 1.07 [95% CI : 0.70-1.65]) whereas compared to control siblings, case siblings had a higher risk of anomalies (OR = 1.54, 95% CI : 0.99-2.42). This increase was likely due to excesses in anomalies of the heart (OR = 2.49, 95% CI : 1.23-5.04). Risk for ALL was elevated in children with a history of a congenital anomaly in their mother (OR = 1.61, 95% CI : 0.80-3.22) or her family (OR = 1.45, 95% CI : 0.94-2.25). Conclusions. Although based on small numbers for specific anomalies, these findings suggest that congenital anomalies are more prevalent in siblings and maternal family of ALL cases than in controls.