engleski

Incidence of Down's syndrome in two regions of Croatia - clustering in time and space?

The Institute of Mother and Child Health as a Regional Center for the registration of congenital anomalies in Europe (EUROCAT) has been continuously registering congenital anomalies in Varaždin and Rijeka form 1983, and form 1986 in Istria and the communities of the Varaždin region. In 1986 we registered and during 1987-88 we confirmed a significant increase in the incidence of Down's syndrome. Moreover, during the whole monitored period (1983-1988) we registered a high incidence of this chromosomal aberration in mothers less than 30. In this study, by verification of all relevant data, we wanted to establish whether the registered higher incidence of Down's syndrome in 1986-1987 period, as well as the high incidence in younger mothers were real or methodological artefacts. Considering the time period in which we observed the higher incidence of Down's syndrome we wanted to establish if the extra irradiation of our population during the Chernobyl accident had any influence on this event. By checking all data that could influence the incidence of Down's syndrome, we established that during the 1986-88 period the incidence of registered cases was significantly higher compared to the 1983-85 period (20.9 vs. 11.9 per 10, 000 respectively). The principal reason for this increase was the inclusion of new regions with a high incidence in our registry. The additional irradiation of our population caused by the Chernobyl accident could not be responsible for the increase of Down's syndrome during 1986-88 period in the investigated areas. Compared to other EUROCAT registries, our registry has the highest incidence of Down's syndrome babies born to them (15.3 per 10, 000 live births vs. EUROCAT centers ranging from 2.7 to 8.7, the average 7.26 per 10, 000). The incidence is also significantly higher when compared to reliable international age specific rates of Down's syndrome. The unusually high incidence of Down's syndrome in younger mothers in regions covered by our Registry would justify the search for a possible etiologic explanations.

Down's syndrome; clustering; Chernobyl

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