A study on limb reduction defects in six European regions.

Limb reduction defects (LRD) gained special attention after the thalidomide tragedy in 1962. LRD are common congenital malformations which present as obvious congenital anomalies recognized at birth. Therefore it might be assumed that they are well documented. However classification of LRDs is disputed as the identification of the exact site of the reduction(s) is hindered by imprecise information. This study was undertaken in 6 European countries to evaluate the use of the new classification proposed by EUROCAT for the epidemiologic and genetic study of LRD. The total number of births including livebirths, still-births and terminations, surveyed during 7 years by the 6 registries of congenital anomalies participating to this study was 611.150. The total prevalence of LRD was 7.06 per 10.000 births including the following categories prevalence : terminal transverse, 3.97, longitudinal, 1.75, proximal-intercalary, 0.10, split hand/foot 0.54 and multiple types 0.70. The prevalence of LRD was statistically higher in Basque Country, Odense, Strasbourg and Groningen than in Belfast and Emilia Romagna. Six per cent of the cases were chromosomal anomalies, including 15 trisomies 18 out of 26 cases, 49.5% (201 cases) were isolated LRD and 50.5% (206 cases) had other major non LRD associated malformations. Sex ratio and maternal age were not statistically different between regions and from the normal population. Multiply malformed with LRD had statistically significantly lower birthweight and lower gestational age than isolated cases with LRD, where available prenatal detection of LRD was higher in multiple malformed children with LRD than in isolated cases, 19.9% and 4.8% respectively. The precurrence risk was 1 in 37.