Link between Consanguinity and Genetic Diseases

Why in news?

Many key insights that are biomedically relevant have been unearthed by looking through the lens of consanguinity.

Consanguinity – It is the practice of marrying close relatives, an age-old tradition that is still practised widely in several human societies.
It is the kinship characterized by the sharing of common ancestors.

Kin are of two basic kinds: consanguineous (sharing common ancestors) and affinal (related by marriage).

It is a social as well as genetic construct.
- Social context- Marriage between individuals related by blood.
- Genetic context (inbreeding)- Marriage between genetically related individuals.
Studies have found that a significant fraction of the global population practises consanguinity and that that has increased the mortality and the rate of recessive genetic diseases in these peoples.
Global status - There is an evidence that suggest those of the Egyptians and Incas, among others, could have practised inbreeding or consanguinity.
Status of India- With more than 4,000 endogamous (groups people marrying within the same caste/tribe or group), India has been a fertile ground for consanguinity.

According to one estimate, approximately 15-20% of the world’s population practises inbreeding, especially in Asia and West Africa.

Social impact- It leads to
- Stable marital relationships
- Improved female autonomy
- Less domestic violence and lower divorce rates
Economic impact- It
- Reduces the instances of dowry and the preservation of landholdings
- Reduces the risk of family financial problems
Cultural impact- Consanguinity provides opportunities for the transmission of cultural values and cultural continuity
- Better compatibility with in-laws
- Ease of marriage arrangements
Genetic traits- Consanguinity may cause homozygosity of alleles in offsprings, preserving the advantageous genetic traits in human as well as animal populations.
Disease protection- Protection against disease has been postulated because of the selection of protective genotypes or homozygosity of protective alleles.
Parental consanguinity seems to protect against breast cancer in the Tunisian population.
The protective role of consanguinity against multiple sclerosis has also been reported.
Health- Consanguineous families are helpful in the identification of novel disease gene by linkage analysis.

Recessive disease- Many modern consanguineous societies, like the Amish population in the U.S., have been studied for recessive diseases.
Autozygosity- Scientist have extensively used autozygosity as an approach to identify new genetic diseases in populations where consanguineous marriage practices is the norm.
Disease- The results of these studies have helped us uncover previously unknown genetic diseases as well as estimate different population’s genetic predisposition to common diseases.
- Recent study suggested that consanguinity could increase the risk and the rate of diseases like type-2 diabetes.
Genomic research- Advances in genomic research will provide innovative solutions to mitigate the risks associated with consanguinity or genetic diseases.
Genetic diagnostics- The genomic research would result in personalised medicine, genetic diagnostics and genetic counselling that will play a pivotal role in improving the health outcomes of affected individuals and their families.

Improved family finances, public health awareness, and higher female education can decrease consanguinity rates.
Premarital genetic screening should be offered for the most common population-specific genetic disorders.
Physicians should be educated on the importance of focusing on consanguinity-associated diseases like hearing loss, thalassemia, cystic fibrosis, intellectual disability, etc.

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