While we acknowledge the concept of child marriage, we fail to address another concerning and prevalent issue, more commonly known as - Consanguineous marriage or Consanguinity.
Consanguinity is a term that refers to the relationship between two individuals sharing a common ancestor or blood. On the basis of clinical genetics, consanguineous marriage can be defined as the union between couples who are related as second cousins or closer. It is a social trend known to be deeply rooted, covering over one-fifth of the global population residing in the Middle East, West Asia, and North Africa and, similarly covers other regions of the world due to emigrants. Among the aforementioned specified regions, consanguineous marriages are favored both culturally and socially, including a greater proportion of the first cousin unions. In contrast, about 8.5% of children have been estimated to have consanguineous parents globally.
The large family size along with the high rates of consanguinity may contribute to the expression of a number of autosomal recessive disorders in individuals, including syndromes which are usually new or rare. The risks of inheriting or expressing the autosomal recessive gene mutations acquired from a common ancestor are extremely high. It is stated that the closer the relationship between the couple, the greater the probability that the progeny will inherit identical copies of the detrimental recessive genes. According to studies, first cousins are assumed to share about 12.5% of their genes and this will lead to their progeny being homozygous at 6.25% of the gene loci. The risks are much lower when the parents are distant relatives, such as second cousins, although this is still greater than the general population. Additionally, the risk also depends on the degree of consanguinity.
These unions are an immense contributor to the risks of developing genetic disorders. Several studies conducted in various parts of the world have led to the association of consanguinity with genetic disorders, showing patients with multifactorial disorders including epilepsy and primary amenorrhea and, autosomal recessive disorders such as phenylketonuria, sensorineural deafness, mucopolysaccharidosis, and neurodegenerative diseases to have the highest rates. Other studies showed a relationship between consanguinity and diseases such as sickle-cell anemia, down’s syndrome, dystrophy, etc. Moreover, cases of stillbirths, child deaths, and recurrent abortions were also seen to be significantly higher among consanguineous parents than non-consanguineous ones.
Due to increased awareness regarding the prevention of congenital and genetic disorders of offspring in some countries, couples belonging to consanguineous communities are seeking counseling, contemplating marriage, and reproduction. However, this tradition remains prevalent in countries like Bangladesh, Pakistan and India where genetic counseling or testing is either limited or absent. While the truth stands that such traditions cannot have any significant change overnight, initial steps and measures involving genetic counseling or genetic testing can be adapted to make informed decisions. Other steps may include providing clear evidence-based guidelines to couples, in order to minimize the risks of having children with genetic disorders or abnormalities. Additionally, carrier detection and genetic counseling methods can also be suggested since they were seen to have reduced the prevalence of inherited disorders in various parts of the world. Moreover, even though premarital genetic screening programs remain a challenge in countries where this tradition is most likely to persist, it should still be kept in consideration. Furthermore, preconception counseling can be advised in which the family history is taken and a four-generation pedigree is constructed to address the risks of their child developing the suspected disorders. These adaptations involving clinical counselors and clinical geneticists, coupled with an increased awareness can ensure a decreased inherited disorder prevalence in many countries, including Bangladesh.