Editorial Team
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A person's relationship with their children needs to be sensitive to the emotions and behaviours of both of them. For example, dealing with inadequate mental health can seriously impact how a person interacts with their child as it can lead to mood swings, and one might get irritated easily. E.g., if you are dealing with depression or anxiety, you might feel unmotivated, lack energy, and have difficulty interacting with your child.
Consanguinity, or the act of marrying/having a relationship with a close blood relative, is a practice that is still prevalent among the general Indian population. It can also be defined as a romantic relationship between two people who come of the same descent. According to various sociological studies, the most common reason why this union between close family members is culturally encouraged is that it strengthens family bonds and increases compatibility between husband and wife, as well as other family members.
However, it has been argued that there could be an increased incidence of genetic disorders in the offspring of a consanguineous couple, primarily because of the closeness in descent and hence the sharing of genes between the partners. The article further gives information about the degree of increased incidence, the reason and prevention for the same.
There are many factors that influence a consanguineous relationship. Some families traditionally follow this method from generation to generation. Other factors include religious influence, literacy levels, and the socio-economic standing of the family. Among the consanguineous marriages, first cousin marriages are the most popular choice due to ideal age differences. These relationships have been observed to be more intimate, also becoming more and more convoluted over time.
Studies have found that, in populations and countries where intrafamilial marriages are prevalent, the risk of an inherited genetic disease is higher than the background risk.
According to the World Health Organization, roughly 3% of all children are born with Congenital Anomalies (CAs), and consanguineous relationships account for more than half of these occurrences. First cousin marriages have been seen to have a 3% increased risk of genetic disorders over and above the 2-3% background risk in the general population.
Humans have two copies of each of the 28000 genes, one copy inherited from either of the parents. When two people, who are closely related i.e they have a considerable number of similar genes, get together and have children, the number of shared genes in the child increases. This increases the odds of inheriting gene mutations (defects) by the offspring from both the parents who may be asymptomatic carriers of the same. Congenital anomalies, birth defects, reproductive losses, stillbirths can occur due to various types of genetic defects.
The type of genetic disorders which occur due to mutations in both the copies of a gene are called autosomal recessive disorders and homozygosity in the state in which a person has identical defective ( mutated) copies of a gene from both the parents. Hence the offspring of consanguineous couples are at increased risk of autosomal recessive genetic disorders because of the expression of gene mutations inherited from a common ancestor. The closer the biological relationship between parents, the greater is the probability that their offspring will inherit identical copies of one or more detrimental recessive genes. First cousins are expected to share about th of their genes and their progeny will have homozygosity at about their genome. If there is any gene mutation in this region of their genome, it would manifest as a genetic defect.
Hence although consanguinity does increase the risk of birth defects to some extent, the majority of these couples have a normal pregnancy outcome. Consanguinity may not be as significant a risk factor for other types of genetic disorders like autosomal dominant disorders, chromosomal disorders, multifactorial disorders as well as infertility or miscarriages.
If a couple's relationship is consanguineous, and/or if there is a family history of a genetic disorder, they could be offered genetic counselling, and they can choose to do genetic testing as a preventive measure. This can highly improve the chances of finding out if they are carriers of mutations in recessive genes and if the resultant offspring may have any genetic implications at all. When done before planning a pregnancy, this can lead to early diagnosis, giving enough time to the couple to decide on the reproductive options. If the couple is found to be a carrier of a mutation in a common gene, there is a 25% chance of passing the mutated copy from both partners to the offspring. This can be tested for by taking a sample from the baby during the early stages of pregnancy and predicting whether there is the inheritance of both mutated copies from parents to the child ( in that case, the baby will be affected by the genetic disease) or has inherited at least one healthy copy (in which case, the baby will be normal).
(The article is contributed by Divya Agarwal - Clinical Advisor, LifeCell Diagnostics)