Associated anomalies in individuals with polydactyly

An epidemiological analysis of the association of polydactyly with other congenital anomalies was performed in 5,927 consecutively born polydactyly cases. They were grouped into three categories: duplicated fifth digit, duplicated first digit, and rare polydactylies; also into isolated or associated groups, if other birth defects were or were not observed in the same infant. Associated cases were further subdivided into: combined, if the other defect was a limb defect; syndromic, if a non-limb defect constituted a recognized causal or pathogenetic entity; and MCA, if a non-limb defect did not constitute a recognized entity. In 14.6% of the 5,927 polydactyly cases studied, polydactyly was not the only congenital anomaly. This associated proportion was minimal for postaxial (11.8%), intermediate for preaxial-I (20.0%), and maximal for rare polydactyly (54.9%). Duplication of the fifth toe plus syndactyly of fourth and fifth toes, as well as other syndactylies adjacent to the duplicated digit is the most frequent type. Syndactyly of fourth and fifth toes was also combined with a duplicated fifth finger, suggesting the existence of an arrested or amputated in utero sixth toe. Polydactylies are rarely associated with other congenital anomalies except in recognizable syndromes. When syndromes are excluded, most of the significant positive associations disappear. Trisomy 13, Meckel, and Down syndrome explained 255 of the 338 syndromic polydactyly cases. Down syndrome is strongly associated with first-digit duplication, and negatively associated with postaxial polydactyly. The latter could not be explained by maternal age differences among Black and non-Black case sub-sets.

Monthly and seasonal variations in the frequency of congenital anomalies

Three large and comparable series of births were used to test the working hypothesis that if there is a real seasonal variation in the frequency of a given congenital malformation; it would have to be shown by adequate analysis; to be more overt in non-tropical areas; and to be six months out of phase in northern and southern hemispheres. The data set were hospital births from tropical (287,165 births) and non-tropical (582,585 births) South America, and from Italy (508,536 births). Sixteen well-defined malformation types were tested: anencephaly, spina bifida, cephalocoele, hydrocephaly, microtia, cleft palate, cleft lip, oesophageal atresia, anal atresia, hypospadias, pes equino-varus, pes talovalgus, postaxial polydactylyl, pre-axial polydactylyl, diaphragmatic hernia, and Down's syndrome. No seasonal variation was proven (p less than 0.01) for any malformation type in any of the three series of data by means of Walter and Elwood's test, or Hewitt et al's non-parametric test2 applied to seven instances with sample sizes smaller than 50 cases. Variations of borderline significance (p less than 0.05) included oesophageal atresia in tropical South America, none in non-tropical South America, and anencephaly in Italy. It is concluded that seasonal variation in the occurrence of congenital malformations is a rare phenomenon when tests are strictly used within their recommended limitations.

Epidemiology of ambiguous genitalia in South America

We present descriptive epidemiologic data on ambiguous genitalia (AG), obtained in the period 1967-1982 by the Latin American Collaborative Study of Congenital Malformations (ECLAMC) through 70 participating hospitals located in 34 cities of 9 South American countries. The observed prevalence rate for isolated AG was about 1/20,000 births, with at least 1/4 and probably as much as 1/2 due to congenital adrenal hyperplasia. When AG cases associated with other congenital anomalies were also considered, the overall frequency of AG was 1/6,900 total births (1/10,000 for live and 1/350 for stillbirths). The prevalence rates were homogeneously distributed among the different countries, and there was a stable secular trend. AG was more frequent in nontropical than in tropical areas of South America, and there was a significant seasonal variation with its acrophase in August (winter). A case-control analysis of 14 risk factors showed an association of AG with a prenatal history of acute maternal illnesses. These data do not support an etiological relationship between AG and hypospadias.