Why are there more cases of mental illness in consanguineous marriages

The probability of mental illness in offspring of consanguineous marriages is higher, mainly related to factors such as the superposition of recessive genetic disease genes, reduced gene diversity, accumulation of harmful mutations, epigenetic abnormalities, and immune system defects.

1. Overlapping of recessive genetic disease genes

The probability of couples with similar blood ties carrying the same recessive pathogenic gene is significantly increased. When both parents pass on the same recessive gene related to mental illness to their children, the risk of their children developing the disease increases exponentially. Common diseases such as schizophrenia and autism spectrum disorder have clear genetic tendencies.

2. Decreased gene diversity

Inbreeding can lead to narrowing of the gene pool and affect the expression of key genes in neural development. The decrease in diversity of the human leukocyte antigen system directly affects synaptic pruning and neurotransmitter balance, and these biological abnormalities are closely related to mental illnesses such as bipolar disorder and depression.

3. Accumulation of harmful mutations

Within three generations of consanguineous mating, harmful mutations in the genome may not be effectively filtered out. These mutations may affect the protein structure of neurotransmitter systems such as dopamine receptors and serotonin transporters, leading to increased susceptibility to mental disorders. Some rare cases of mental retardation syndrome are directly related to this.

4. Epigenetic abnormalities [SEP]: DNA methylation patterns and histone modifications in close relatives and offspring are prone to disorder. This epigenetic change may continue to affect the function of the hypothalamic pituitary adrenal axis, causing dysfunction of the stress response system and increasing the risk of anxiety disorders, post-traumatic stress disorder, and other diseases.

5. Immune system deficiency

Offspring of consanguineous marriages often exhibit immune regulation abnormalities, and maternal inflammatory reactions during pregnancy may interfere with fetal neural development. Research shows that there is a correlation between prenatal infections and offspring schizophrenia, and this immune nervous interaction mechanism is more prominent in consanguineous families. To reduce the genetic risk of mental illness, it is recommended to undergo professional genetic counseling and genetic testing before marriage. In daily life, it is important to create a stable family environment, ensure balanced nutrition during pregnancy, and avoid exposure to teratogenic substances. For individuals who have already experienced mental symptoms, they should seek medical attention at a psychiatric hospital as soon as possible and improve their prognosis through comprehensive measures such as medication intervention, psychological therapy, and social function training. Regular mental health screening, establishing scientific sleep habits, and maintaining moderate exercise can all help maintain neurological health.