Consanguineous Marriage

Consanguineous marriage is a state of blood ties between the married people. The risk increases according to the degree of closeness between people. For example, a couple who has a 1st degree cousin marriage (children of aunts, uncles) is more at risk of having children with hereditary diseases than a couple who has a 2nd degree cousin marriage (such as marriages between children of grandparents).

The importance of genetic counselling is obvious in our country where consanguineous marriages are very frequent. Consanguineous marriage plays a role in many diseases that are inherited autosomal recessively. Therefore, related couples should receive genetic counselling in order to determine the risks of these diseases. Generalization of genetic counselling is amajor necessity in our country's conditions.

Structures called genes enable the transfer of various features from parents to the next generation. In these genes, disorders called mutations that affect human health may occur for any reason and people can transfer these disorders to the next generation. Every person keeps these genes in pairs because they are taken from the mother and father. If a disease can be caused when there is a mutation in one of the two relevant genes it is a dominant disease, when it is a double dose, that is, when the mutation is carried in two relevant genes it is called recessive disease. Every person has the possibility of carrying mutations that cause recessive diseases without any symptoms of disease, i.e. they are carriers of these diseases, and it is difficult to diagnose these people unless they have a relative or child who shows this disease. Since relatives take their genes from a common ancestor, they are more likely to have mutations in the same gene than non-relatives.

In this way, the risk of this disease will be 25% in every child of a couple carrying a mutation in the same gene. Unfortunately, many families become aware of this situation only after an affected child is born. Therefore, it would be appropriate to evaluate and inform couples who wish to marry a relative before the marriage, if possible, by a geneticist before having a child and, if necessary, to have some tests done.

Consanguineous marriage is the marriage made by people of the same family. Among the causes of consanguineous marriages are social, cultural and economic factors.

The frequency of consanguineous marriages in Turkey is 20.9%. However, while this ratio increases to 40.4% in the South-eastern Anatolia region, it decreases to 4.8% in West Marmara. As the consanguineous marriage is so common in Turkish society, it increases the risk of recessive inherited diseases in children born in these marriages. For example, every child born from the mother and father who are carriers for recessive inherited diseases has a 25% risk of being “affected” regardless of gender.