Karnataka has the highest number of women aged 15-49 married to a first cousin from their mother’s side, according to the recently released National Family Health Survey (NFHS-5) report.
While 13.9% of the female population in the State is married to a cousin from the mother’s side, 9.6% is married to a cousin from the father’s side. Marriages to a woman’s second cousin and uncle were at 0.5% and 0.2%, respectively. About 2.5% of consanguineous marriages were to other types of blood relatives and 0.1% to those who were previously brothers-in-law, according to the report.
States with highest consanguineous marriages
National average: 11%
Tamil Nadu: 27.9%
Karnataka: 26.6%
Andhra Pradesh: 26.4%
Puducherry: 19.2%
Telangana: 18.2%
Overall, the State has the second-highest number of consanguineous marriages. While Tamil Nadu tops the list where 27.9% of the female population is married to close blood relatives such as cousins, uncles, and brothers-in-law, Karnataka follows with 26.6%. The national average is far lower at 11%, according to the survey that was conducted between 2019 and 2021.
Young women are much more likely than older women to be related to their husbands. Women in urban areas are about equally as likely to be in consanguineous marriages as are women in rural areas. Religion-wise, Muslim and Buddhist/Neo-Buddhist women are the most likely to be in consanguineous marriages.
Genetic disorders
Consanguineous marriages are one of the factors for increased genetic disorders among children. Doctors said the closer the biological relationship between parents, the greater is the probability that their offspring inheriting identical copies of one or more detrimental recessive genes.
States/UTs with highest mother’s side cousin marriages
National average: 4%
Karnataka: 13.9%
Andhra Pradesh: 11.6%
Tamil Nadu: 11.2%
Puducherry: 7.6%
Telangana: 5.3%
Namitha A. Kumar, thalassaemia patient advocate from Open Platform for Orphan Diseases, said if people are marrying within the family, they should get themselves tested for recessive carrier genes such as thalassemia, sickle cell disease, primary immunodeficiencies, and spinal muscular atrophy. All tests should be run during pregnancy like screening for the trisomies and other congenital birth defects, she said.
Consultant obstetrician and gynaecologist Hema Divakar said rather than discouraging consanguineous marriages in populations with such long-held tradition, ensuring access to preconception and premarital counselling services is the logical way to proceed.
“This is more likely to receive community acceptance. Increasing public literacy on consanguinity could be achieved by providing proper education and training to primary healthcare workers on all health and social issues related to consanguinity,” she said.
Counselling
Sheetal Sharda, clinical geneticist, and director, Genomics Development and Implementation at Neuberg Centre for Genomic Medicine, said since the couples in consanguineous marriages share a common ancestor, the genes shared also are common. “There is a higher chance of them being carriers of an abnormal gene, leading to an autosomal recessive genetic disorder as opposed to marriages in non-consanguineous couples,” she said.
States/UTs with highest father’s side cousin marriages
National average: 4%
Andhra Pradesh: 10.5%
Tamil Nadu: 10%
Telangana: 9.9%
Karnataka: 9.6%
Puducherry: 7.6%
“Such families can be counselled regarding their high risk of having an affected child and guided on appropriate reproductive decisions. Carrier screening can be offered before they plan a pregnancy and if they are found to be carriers, prenatal diagnosis after pregnancy or pre-implantation genetic testing can be offered,” she explained.
N. Sapna Lulla, Lead Consultant — Obstetrics and Gynaecology at Aster CMI Hospital, said the hospital was seeing many young couples coming for counselling. “We refer them to the genetic counsellor if they fall in the consanguineous marriage category,” she said.
Mitesh Shetty, who heads the Department of Medical Genetics at Manipal Hospitals (Old Airport Road), said premarital carrier screening was now being accepted by communities who have understood the implication of having a child with a genetic disorder. “Appropriate genetic counselling for such couples will benefit them as well society at large in bringing down the incidence of severe genetic disorders,” he said.
