Evidence for a New Allele in the Kidd Blood Group System in Indians of Northern Mato Grosso, Brazil

A NEW phenotype in the Kidd blood group system, Jk (a–b–), has recently been recognized in a Filipina of Spanish and Chinese ancestry¹. This phenotype is extremely rare in Whites and Negroes; its incidence in Asian people or their descendants has not as yet been determined. We recently had the opportunity to study the blood groups of a number of Brazilian Indians indigenous to the northern part of Mato Grosso in the region of the headwaters of the Upper Xingu River. Because of the peculiar geographical features defining this area, these Indians live in virtual isolation, and because of tribal customs, marriage is exclusively between first cousins. The present communication reports the frequency of the phenotype Jk (a–b–) and evidence for a new allele, Jk, in a sample of this population.