Consanguinity and endogamy in the Netherlands: demographic and medical genetic aspects.

This paper reviews what is currently known about the presence of consanguinity and endogamy in the Netherlands, in the past and today, and concludes with a discussion of medical genetic aspects. First geographic characteristics, the demographic history, the genetic make-up of the native population, legal aspects and the public opinion are reviewed. Then data on the prevalence of consanguinity in the native population are presented for marriages since 1840, followed by data on consanguineous marriages among immigrants from countries with a tradition of close-kin marriages. It is estimated that approximately 1% of at-risk consanguineous couples are referred to clinical genetic centres for prospective genetic counselling in the Netherlands. This picture will change dramatically if and when next-generation sequencing is introduced to identify couples at ≥ 25% risk prospectively.