Supplementary Material for: Prevalence Estimates of Rare Congenital Anomalies by Integrating Two Population-Based Registries in Tuscany, Italy

Background/Aims: Population-based registries play a key role in the epidemiological surveillance of congenital anomalies (CAs). This study is aimed at improving the epidemiological surveillance and providing prevalence estimates of rare CAs using the Registry of Rare Diseases as an added data source to the Registry of Congenital Anomalies. Methods: Cases of diagnosed rare CAs (2006-2013) were extracted from the Tuscany Registry of Rare Diseases and the Tuscany Registry of Congenital Anomalies in order to set up an integrated dataset. Prevalence (per 100,000 births; 95% confidence interval) was calculated for each rare CA. Results: Overall, 56 rare CAs were analyzed including 656 cases, of whom 121 (18.4%) were retrieved from the Registry of Rare Diseases that provided a major contribution for rare CAs for which a prenatal diagnosis is difficult, or for CAs more easily diagnosed in the postneonatal period. After data integration, an increased prevalence estimate was observed in particular for atresia of bile ducts (6.24; 3.57-10.14), tuberous sclerosis (2.34; 0.86-5.10), Kabuki syndrome (1.95; 0.63-4.55), and some monogenic CAs. Conclusions: This study represents an example of integration of registries operating in the field of rare diseases. Providing the accurate prevalence of rare CAs is a key point to improving surveillance, supporting public health policies, and planning healthcare.