Oculocutaneous albinism and consanguineous marriage among Spanish Gitanos or Calé--a study of 83 cases.

This paper studies 83 cases of oculocutaneous albinism (OCA) in family networks of Gitanos in southeastern Spain, and analyzes their sustained inbreeding patterns and complex genealogical relationships. It is based in the family and genealogy reconstitution of the Gitano population of 22 contiguous localities using ethnographic and historical demography methods. The study found a prevalence of OCA among Gitanos in the area of about 1: 1,200. Most of the cases belong to three extended kin networks in which consanguineous marriages have been common for generations. In these networks there are other cases of visual and auditive congenital anomalies, and other birth defects such as brachydactily, polydactily, neurological defects, Potter Sequence, etc. In 61 OCA cases it was possible to trace inbreeding links with a depth of three to nine generations. For these cases the estimated alpha (average of the inbreeding coefficient, F) is 0.0222. Relationships between the parents of people affected are of three types: close, as between first or second cousins; distant, as between third or fourth cousins, and non-existent, as in mixed marriages. In most cases, however, persons with albinism are linked by multiple consanguineous links. Albinism seems to be a visible example of a high prevalence of birth defects in this minority, associated with founder effects, sustained inbreeding and high fertility rates. These conditions derive from Gitano's marriage preferences and pronatalist strategies. In turn, these strategies have to be related to the exclusion, persecution and segregation that Spanish Gypsies have suffered for centuries.