FACIAL CLEFTING AND AMERINDIAN ADMIXTURE IN POPULATIONS OF SANTIAGO, CHILE

Among congenital malformations, cleft lip with and/or without cleft pa late has the highest relative frequencies and shows ethnic variation i n prevalence. Both malformations are generally more common among the A sian than European populations. Many populations of Chile have genes o f Amerindian and Spanish ancestry, with considerable variation in the degree of Amerindian admixture. Therefore, the association of clefting incidence with Amerindian admixture was investigated. The frequency o f cleft lip and/or cleft palate in infants born in three private and t wo public maternity service clinics of Santiago, Chile, is reported. T he private clinic patients have a higher socioeconomic status (SES) th an those receiving the public services. They also differ in estimated Amerindian admixture. More than 200,900 consecutive birth records were reviewed. The rate of clefting malformations is 15.3 per 10,000 live births. Based on allele frequencies at the ABO and Rh blood group loci , the percentage of Amerindian admixture is higher in infants born in the public compared to those born in the private maternity service cli nics. Amerindian admixture is positively correlated (Spearman's rho = 0.9, P = 0.008) with clefting rate across these samples. Clefting is a lso associated with SES, with lower SES showing higher clefting rates. Mothers of clefting newborns also have higher estimated Amerindian ad mixture compared to those of normal newborns. The results support the view that in Chilean populations, susceptibility to clefting is relate d to Amerindian ancestry. (C) 1997 Wiley-Liss, Inc.