SICKLE CELL TRAIT AND GENETIC COUNSELING

MR. JONES H. MUNANG'ANDU

Sickle-Cell Anemia is a genetic disorder of the blood leading to frequent and severe infections, damage to major organs, and episodes of unpredictable pain in the back, chest, abdomen, and extremities. Early symptoms appear at about six months of age and may include serious infections, pain and swelling in the hands and feet, and enlargement of the abdomen and heart. The incidence of certain genetic diseases can differ among human populations as a result of environmental adaptation. One such case is the high occurrence of sickle-cell anemia among peoples of sub-Saharan Africa compared to other groups. Sickle-cell anemia is caused by a mutated gene that produces an abnormal form of hemoglobin, a protein that transports oxygen in the bloodstream. The abnormal hemoglobin, called hemoglobin S, deforms red blood cells from their normal disc shape into the shape of a crescent, or sickle. Not every person with the sickle-cell gene, however, suffers from sickle-cell anemia. Only individuals, who inherit two copies of the sickle-cell gene, one from their father and one from their mother, contract the illness. People who inherit one sickle-cell gene and one normal hemoglobin gene have what is known as the sickle-cell trait. These people generally do not have any health problems, but they can pass the abnormal gene to their children.

Since people with sickle-cell anemia often die before reaching reproductive age, scientists initially wondered why the forces of natural selection had not eliminated the sickle-cell gene from human populations. The answer, proved by experiments in the 1950s and by later observations, is that having one copy of the sickle-cell gene makes an individual resistant to the most common form of malaria called Plasmodium falciparum, a deadly disease caused by parasites and transmitted by mosquitoes. In malarial areas such as sub-Saharan Africa, carriers of one sickle-cell gene have a survival advantage over individuals with normal hemoglobin genes, who lack resistance. Individuals with protection from malaria will live longer and produce more children, so natural selection maintains the sickle-cell gene. However, whenever two carriers of the sickle-cell gene mate, by chance some children will inherit the gene from both parents and will suffer from sickle-cell.

An individual with history of sickle cell anaemia in the family may seek genetic counseling or a sickling antigen test to establish if they are carriers and take the necessary giant step of preventing further occurrence of sickle cell anaemia. Genetic counseling may involve more than one visit between a counselor and a client, who may be an individual, a couple, or an entire family. During the first visit, the counselor gathers information about the client's family medical history. The counselor may discuss options for diagnostic tests that could help determine if a person is at risk for passing an inherited disorder on to children or is susceptible to a particular genetic disease. After considering these options, the client may choose to undergo testing at that time or in a follow-up session. When testing is completed, the genetic counselor analyzes the family history and test results to determine whether a genetic disorder exists within a family and, if so, how it is inherited. The counselor then discusses those conclusions with the client. Genetic counselors help the client cope with the emotional repercussions of the diagnosis as well as any practical concerns. Genetic counselors respect the privacy of the individual and family, keeping all information exchanged during counseling sessions confidential. The parents of a newborn diagnosed with a genetic disease may ask a genetic counselor to explain the progression of the disease and describe the types of treatments required to keep their baby healthy.

A couple that is thinking about conceiving a child may want to consider genetic counseling for several reasons. For instance, many women aged 35 or older seek genetic counseling because they are at a higher risk than younger women of giving birth to a child with a chromosomal abnormality. These abnormalities occur when a child inherits all or part of an extra copy of a chromosome. Down syndrome, the most common chromosomal disorder, is almost nine times more common in babies born to women aged 40 than those born to women aged 30. Couples who already have a child who was born with a genetic disorder may seek genetic counseling to determine the risk that future children may be similarly affected.

Expecting couples concerned about the health of their unborn baby may request genetic counseling to learn if the baby is at risk for a disease. A pregnant woman may worry that she has been exposed to factors that can hurt the development of her fetus, such as infectious diseases, medications, alcohol, nonmedical drugs, or radiation but genetic counseling can offer solution to such anxiety.

The parents of a newborn diagnosed with a genetic disease may ask a genetic counselor to explain the progression of the disease and describe the types of treatments required to keep their baby healthy. If environmental conditions change and affect the malaria rate, the frequency of the sickle-cell gene can also change .The frequency of the sickle-cell gene in a population depends on the intensity of malaria where that population lives. Besides the sickle-cell trait, many other genetic conditions confer some degree of resistance to malaria and are frequent in areas where malaria is widespread. Thalassemia is a blood disorder that can cause mild to severe anemia. Thalassemia results from the inheritance of certain mutated genes that produce an abnormal form of hemoglobin. Like the sickle-cell gene, people can carry thalassemia genes without suffering from the disease, and carriers are partially resistant to malaria.

JONES. H. MUNANG'ANDU (author)
Motivational speaker, health commentator &
Health practitioner
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