HEALTH : ‘Procreation between first cousins is unhealthy!’

In clinical genetics, approximately 1.1 billion people currently live in countries where consanguineous marriages are customary. Cancer, mental disorders, hypertension, hearing loss, diabetes mellitus, epilepsy, asthma, leukaemia, beta thalassemia, and congenital and noncongenital heart diseases are all risks for the children of consanguineous parents! In this week’s Health Talk, Shikha Duggal looks at genetic disorders linked to consanguineous marriages.

Not just in films, but in real life too, people have married their cousins. Cousin marriage is an intriguing concept because it is the root cause of the demise of a family of German royalty in the 15th century. There’s a special term used for these marital unions called “consanguineous.” The question is now, “How is it leading to higher rates of genetic disorders?”

“In clinical genetics, approximately 1.1 billion people currently live in countries where consanguineous marriages are customary, and among them, one in every three marriages is between cousins. The frequency of genetic disorders among such children is around twice that of children of non-related parents! It is associated with an increased risk of “congenital malformations” and “autosomal recessive diseases” with resultant increased postnatal mortality in the offspring of first-cousin couples, and such infants usually die in the first month of birth. Cancer, mental disorders, hypertension, hearing loss, diabetes mellitus, epilepsy, asthma, leukaemia, beta thalassemia, and congenital and noncongenital heart diseases are all risks for the children of consanguineous parents! Severe “mental retardation” is associated with consanguinity because many autosomal recessive conditions include moderate-severe MR. Most studies are unclear on the impact of consanguinity on the fertility of couples. At the moment, the data is comparable between the two groups. Because it’s a sensitive topic, we can’t reveal the case study right now,” explained Dr. Ravish I R, a urologist at Aster RV Hospital!

Ghafoor Hussain Shah was a 56-year-old teacher and father of eight children in Kashmir. According to tribal customs there, he said he is expected to arrange the children’s marriages within his extended family. However, he knew about the potential risks of genetic disease prevalent in children from inter-family marriages. He married his maternal cousin in 1987, and three of their children now suffer from disorders. This is what the doctors are warning about!

“Each cell in our body has 23 pairs of chromosomes, and we all get genetic material, half from our mothers and a half from our fathers. Through cousin marriages, genetic material is exchanged within the family, and if these continue for several generations, there is a chance of genetic problems in babies. For single-gene disorders, there are basically five different ways that inheritance can occur: autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, and mitochondrial. In cousin marriages, there is a high chance of having carriers for the disease who appear normal, but offspring might be affected if both parents are carriers. The most common diseases that are seen in cousin marriages are “blood diseases.” In a third-degree consanguineous marriage, the wife is the husband’s sister’s daughter. Many generations of their family had cousin marriages. The husband’s grandfather had a hearing problem that went unnoticed until he was an adult. They have two sons, both of whom were normal at birth. In their college days, both boys started having hearing difficulty and were diagnosed with sensorineural deafness and are now on hearing aids,” informed Dr. Sarada M., consultant obstetrician and gynaecologist at Yashoda Hospitals in Hyderabad.

Dr Ruchi Bhandari, Consultant Gynaecologist, Infertility Specialist & Cosmetic Gynaecologist at Mishka IVF Centre, Jaipur explains “Demographic and socioeconomic factors must be carefully managed. No significant negative correlations have been found between reproductive indicators like miscarriages and fertility. It is essential to understand that if repeated cousin marriages occur in specific groups, then the relationship increases between two cousins who are half-siblings, which is even more dangerous, so it is essential to understand the history of the spouses and the historical relationship between them. This leads to increased congenital disabilities and genetic disorders in the offspring. Genetic counselling must be done for such spouses whenever they come to the OPD. People frequently ponder why a child in a consanguineous marriage is typically diagnosed with a genetic disease. It is so because most people get roughly 50% of their genes from both parents. In these situations, there is a 25% probability that the faulty or recessive gene carried by both parents will be passed on to their child. According to a study, 19.7% of consanguineous couples were more likely to have a child who had a genetic disease. In the study of British communities of Pakistanis, it was found that they have been carrying a lot of genetic diseases and multiple mental and physical abnormalities as they have been following the practice of cousin marriages for many years. According to the study, 700 babies are born each year with congenital disabilities, which is a significant number that proves cousin marriages are not ideal for offspring.”