Diseases related to consanguineous marriage arise due to the concentration of genetic inheritance. Since the carrier rate is high in such marriages, metabolic, neurological, and developmental problems are observed more frequently in children. Early diagnosis and genetic counseling are of great importance.

The frequency of genetic diseases increases in consanguineous marriages. Especially diseases inherited in an autosomal recessive manner may create severe clinical pictures in the child. These conditions may manifest with findings such as intellectual disability, epilepsy, or muscle diseases.

Some neurological disorders are caused by genetic mutations resulting from consanguineous marriage. Metabolic syndromes seen in childhood, progressive brain damage, or movement disorders are included in this group. Detailed genetic tests are required for diagnosis.

Preventive methods include premarital genetic screening and counseling services for families. Early screening in at-risk families helps detect treatable metabolic diseases early and prevent complications.

Which Genetic Diseases Can Consanguineous Marriage Cause in Children?

Consanguineous marriage may increase the frequency of blood diseases such as thalassemia, sickle cell anemia, and G6PD deficiency; metabolic diseases such as cystic fibrosis and Tay-Sachs disease; and other congenital anomalies such as congenital heart defects and kidney diseases.

Why Does Consanguineous Marriage Increase the Risk of Genetic Disease?

In consanguineous marriage, due to genetic material inherited from common ancestors, the mother and father are more likely to carry the same recessive gene mutations. This significantly increases the risk that their children will receive two copies of this mutation and develop the disease.

Now let us think of this situation like this: Each of us carries a “genetic bag” full of genes inherited from our mother and father. Inside this bag, along with our healthy traits, there may also be “hidden” seeds of some diseases. If the married couple are not relatives, the likelihood that the hidden seeds in these two bags belong to the same disease is low. However, in consanguineous marriage, since the contents of the bags are more similar, the possibility that the same “disease seed” exists in both parents and therefore comes together in the child increases. This becomes especially more apparent in what we call “recessive” conditions, that is, conditions in which the same faulty gene must be inherited from both parents for the disease to appear. Just like two keys opening one lock, for the child to be affected, the faulty genes inherited from both parents must come together. In consanguineous marriage, the probability of these “matching keys” coming together is higher.

What Health Problems Can Consanguineous Marriage Cause in Children?

Consanguineous marriage can also cause health problems such as intellectual and developmental disabilities, hearing and vision problems, muscle diseases, epilepsy, diseases associated with brain degeneration, increased susceptibility to infections, blood diseases, metabolic diseases, and heart and kidney diseases.

• Intellectual and Developmental Disabilities (IDD): Consanguineous marriage is a known risk factor for genetic disorders presenting with IDD. Studies conducted in India and Morocco show that the rate of consanguineous marriage is higher among parents of children with IDD. This may include specific conditions such as autism spectrum disorder and fragile X syndrome. Research has identified specific gene mutations in consanguineous families with IDD.
• Sensory Disorders: Hearing and vision problems at an early age may be potential indicators of genetic disorders that are more common in consanguineous families. Studies have shown a high frequency of non-syndromic hearing loss (NSHL) in consanguineous families in regions such as Pakistan and India.
• Among muscle diseases, spinal muscular atrophy, popularly known as SMA, diseases associated with muscle wasting, and some diseases called myopathies associated with structural muscle abnormalities are related to consanguineous marriage. These diseases may impair vitally important functions such as the child’s mobility and respiratory functions.
• A group of diseases that we call neurodegenerative diseases, which progress with the progressive loss of brain and spinal cord functions, are also related to consanguineous marriage.
• Increased Child Mortality and Morbidity Rates: Consanguineous marriage is associated with a slight increase in miscarriages and infant deaths. Under-5 mortality is significantly higher in children born from marriages between close relatives. Studies show an increase in neonatal and post-neonatal mortality in children born from consanguineous marriages due to the expression of harmful recessive genes.
• Susceptibility to Infections: Some studies show that among cases affected by infections such as tuberculosis and hepatitis in populations with high rates of consanguineous marriage, consanguineous individuals are more common. This may be associated with low genetic heterozygosity. However, other studies have shown variable or even negative associations with specific infections such as HIV-1, which may be related to the inheritance of protective gene variants.

In children, blood diseases such as thalassemia, sickle cell anemia, and G6PD deficiency are seen more frequently as a result of consanguineous marriage.

Some studies show that consanguineous marriage increases the risk of congenital heart defects and kidney diseases.

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