A consanguineous marriage is a situation of a blood tie between people who will get married. The risk increases according to the degree of closeness between people.

In our country, where consanguineous marriages are very common, the importance of genetic counselling is indisputable. In many autosomal recessive hereditary diseases, consanguineous marriage is involved. For this reason, couples with kinship should receive genetic counselling in order to determine the risks of these diseases. Spreading the importance of genetic counselling is a necessity in our country’s conditions. Genes enable the transfer of various features from mother and father 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 has these genes in pairs because they are taken from the mother and father. A disease is dominant when one of the two genes is mutated, and it is called recessive disease when the mutation is carried in two related genes. People can carry mutations that cause recessive diseases without any symptoms of disease, that is, they are carriers for these diseases, and it is difficult to diagnose them 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. Thus, 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 will be appropriate to evaluate and inform couples who wish to marry a relative by a geneticist before the marriage, if possible, before having a child and, if necessary, to have some tests done. Social, cultural and economic factors are among the causes of consanguineous marriages. The rate 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. Being so common in Turkish society the consanguineous marriage increases the risk of recessive (nondominant) inherited diseases in children born from these marriages. For example, every child born of mother and father who are carriers of recessive inherited diseases has a 25% risk of being “affected” regardless of gender.

Some of the genetic diseases that are detected in our country as a result of consanguineous marriage are as follows:


One of the rare hereditary metabolic diseases. The average incidence of babies born alive in our country is 1 / 3000- 1/4000. The most important features of the disease are progressive mental retardation and other nervous system findings. Babies with this disease look completely healthy for 1-2 months after birth. The findings begin to appear after the second month. The decline in intelligence becomes evident. Stages of development lag behind their peers, they cannot improve their sitting, speaking and walking skills. In this disease, it is very important to make an early diagnosis and take appropriate approach without affecting brain development. The disease is screened with heel blood taken from the baby after birth, and the diagnosed babies should be fed poorly from the amino acid of phenylalanine for life. If phenylketonuria is detected by newborn screening and treatment is not started in the first 3 months, it is inevitable to develop severe mental retardation.

Cystic Fibrosis

The incidence of babies born alive in our country is approximately 1/2500. The basis of the disease lies in dysfunction of the chlorine ducts in the skin and various internal organs as a result of the mutation. As a result – problems such as recurrent lung infections, retarded development, chronic and persistent sinusitis, pancreatitis, intestinal dysfunction in the newborn period, diabetes, liver diseases and male infertility in the elderly. The diagnosis of the disease is made in addition to clinical findings, with biochemical and genetic tests. Its treatment is lifelong, supportive treatment for the systems affected by the disease should be provided, there is no definitive treatment.

Familial Mediterranean Fever (FMF)

A hereditary disease characterized by recurrent fever, abdominal pain, and recurrent chest and joint pain in some individuals. As a result of recurrent pain attacks, a protein called amyloid accumulates in the body, and it can cause kidney dysfunction and kidney failure, especially as a result of its accumulation in the kidneys over the years. In the treatment of the disease, a medicine called Colchicine is used. This drug does not eliminate the disease, it reduces the frequency and severity of attacks, and prevents the loss of kidney function, the most frightening consequence of the disease. The medicine should be used for a lifetime.


Also known as Mediterranean Anemia is a type of anemia which is more common in Mediterranean countries. According to loss of function in beta globin genes, thalassemia is classified as major and minor. If the individual has a single allele from the mother or father, that individual is called thalassemia minor (thalassemia carrier), if both alleles are defective, it is called thalassemia major (mediterranean anemia). Thalassemia major is a condition that starts in infancy, can be observed with severe anemia, changes in the shape in facial bones related to anemia, and heart failure in the future; in its treatment, lifelong recurring blood transfusions are required. Thalassemia minor has a lighter course than thalassemia major and the need for blood transfusions is less. As a result of repeated blood transfusions, iron accumulation can be observed in various organs in the body and patients are given intended treatment.

Inherited Metabolic Diseases

Diseases affecting various systems as a result of inadequate or absence of a particular protein or enzyme as a result of mutation in both alleles of the gene associated with the disease. There are many metabolic diseases and their most common findings include retarded development and mental retardation, internal organ diseases, musculoskeletal disorders, phenotypic (external) changes, vision or hearing problems. There is no cure for these diseases, but for some people to replace the missing enzyme treatments are attempted.