The Cayapa Indians of Ecuador: a population study of seven protein genetic polymorphisms.

The Cayapa Indians are a population of 3600 individuals living in Ecuador, along the Cayapas River and its tributaries. They are thought to have migrated from the Andes, north of Quito, and settled in the Cayapas area five centuries ago as a consequence of Inca expansion and of the Spanish conquest. In order to study the genetic structure of the Cayapa and their relationships with other native American peoples, and to enquire on the possibility of admixture from nearby Black communities, we have investigated a sample of 139 individuals for seven plasma genetic markers (F13A, F13B, ORM1, AHSG, C6, C7 and APOC2) by isoelectric focusing and immunoblotting. The following gene frequencies have been found: F13A*1 = 0.824, F13A*2 = 0.176; F13B*1 = 0.126, F13B*3 = 0.874; ORM1*1 = 0.554, ORM1*2 = 0.446; AHSG*1 = 0.275, AHSG*2 = 0.725; C6*A = 0.131, C6*B = 0.814, C6*A21 = 0.055; C7*1 = 1.000; APOC2*1 = 1.000. The findings confirm, whenever the comparison was possible, quite a good resemblance of the Cayapa with other Native American populations.