Dr. Swarkar Sharma
There is this string that makes us Human and binds us together, called the Human DNA, inherited from our ancestors. Every human shared the ancestors and thus share the DNA. DNA is the blueprint of life.
It is present in each organism whether it is single cell like bacteria or with many cells like Human. It holds information as instructions, necessary for a living organism to grow and live. HOW DNA Works? The DNA strand is made of string of 4 letters. A, T, G, C. these letters in specific pattern make words and these words together make sentences called the “genes”. We can simply correlate that the sentences carry instructions. These genes tell the cell to make proteins which enable a cell to perform specific function. So for different type of functions, different genes exist which code for different proteins. With some exceptions, there are two copies of each gene in each individual. One copy is inherited to child from father and another from the mother.
During this process, sometimes errors may occur called the Mutation. As we considered gene as a sentence, let us try to understand it with this example of a sentence, “the car hit the dog”. Lets assume, this is the message of our gene. While DNA is making its copy, there is possibility of different errors. if any of these errors occur, it could be like”the car hit the Fog”, changing the meaning or jumbled up sentence, losing its messagedue toletter rearrangement like “the Car hit the dog” or different meaning due to words rearrangements like”hit the car the dog”. The same may happen with the protein if gene has some change. So occurrence of error may result in change in function or altered function of protein. However, these changes may have neutral, positive or negative impact.
We are more concerned about negative impact and specifically when both the copies of the gene have mutation. Let’s assume, there is a mutation in one copy of gene in mother, may be she has inherited it from either of her parents. As long as father and mother contributed normal copy of gene, kid is normal. If mother has inherited the mutated gene, the normal gene from the parents tries to compensate and disease may not appear and kid though is a carrier yet appears unaffected.
Now lets explain the situation. If mother has a carrier cousin who has a carrier daughter and both families decide to marry their kids. Now if both the carriers inherited normal gene copy, kid is normal but if both inherited mutated copy, the severe disease appears and kid is affected and is the scenario called as recessive disorder. Recessive disorders are many a times lethal and most of the times severely affect the patients. Though it is random process and chance that an individual is normal, carrier or affected but the probability and possibility of recessive diseases increases by manifolds when marriage is within highly close group or within a family. This happens because chances increase that both parents inherit mutated copies of the gene. Closer the relationship, higher is the possibility of inheritance of both mutated Gene copies and appearance of a disorder. Especially it is alarming and critical for the families where incidences of such disorders already exist.
In Jammu and Kashmir (J&K), the rate of consanguinity is relatively high due to restricted geographical localization, endogamous population groups and utmost, majority population performs relatively high consanguinity. Since, consanguinity is widely prevalent in majority population, a very high prevalence of several rare human genetic disorders, yet to be identified and characterized, is suspected. In many of such disorders, that are not lethal in early age, individuals remain normal at birth and have disease symptoms later in age that keep on intensifying with advancement of age, sometimes resulting in loss of life. These disorders might have remained unidentified due to geographical isolation, less awareness and limited clinical resources. These disorders as such appear rare however, if unattended in due course may turn out to be huge problem and start to effect at population level instead of being restricted to limited families.
(The author is Human Genetics Research Group, Shri Mata Vaishno Devi University Katra)
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