El hechizo genético de los Austrias

Abstract

The Spanish branch of the Habsburg dynasty, the Spanish Habsburgs, ruled over the world-wide Spanish Empire from 1516 to 1770. That year Charles II, the last Spanish Habsburg king, died without heir since no children were born from his two marriages. A number of historians have suggested that the high incidence of consanguineous marriages could be the cause of the extinction of the Spanish Habsburg lineage. This hypothesis is very suggestive and is commonly accepted in the present historical literature. The large body of information on the Spanish Habsburgs in terms of genealogical records and child mortality data allow us to check the inbreeding hypothesis from a genetic perspective. The inbreeding coefficients of the Spanish Habsburg kings and their children computed from an extended pedigree of the dynasty gave precise information on the inbreeding level attained by the lineage and allowed for searching the inbreeding consequences on child mortality. The complex symptoms showed by Charles II, who suffered from an important number of health problems along his lifetime, could be due to a genetic disorder XXY (Klinefelter syndrome) or a XX male syndrome according to several authorities in medicine. These hypotheses had been raised from a medical perspective to explain Charles II´s infertility but they did not consider in a precise way the genetic context in which the king´s health problems were originated. Here, we evaluate these hypotheses on the basis of the genomic effects of inbreeding