Complex segregation analysis of 1,792 cleft lip and palate families in South America: 1967-1997

although several studies have demonstrated familial aggregation of nonsyndromic cleft lip with or without cleft palate (cl/p), its model of inheritance remains uncertain. we report the results of complex segregation analysis performed in south american families with a newborn affected with cl/p. families of 1,792 consecutive newborns affected with cl/p and registered during the period 1967 to 1997 were studied. a model that did not include a major locus was the best-fitting model for cl/p families. this result is in agreement with previous studies which showed a significant association of several putative susceptibility loci and cl/p, indicating that the genes involved in cl/p are likely to have only a very modest impact on disease risk.