To Prevent Sickle Cell Disease, Know Your Genotype Before Marriage - Professor Michael Kehinde

 

Who has Sickle Cell Disease, SCD, and why are some people born with this disease? In the view of Professor of Medicine, Department of Medicine, College of Medicine, University of Lagos, CMUL, Professor Michael Kehinde, not less than 300,000 children are born with one form of SCD every year mostly, in sub-Saharan Africa, where malaria is common.

Kehinde, a Specialist Physician and Clinical Haematologist who for more than two decades, headed the Clinical Haematology Unit at the Lagos University teaching Hospital, LUTH, says parents who fail to verify their genotype before they get married, are to be blamed when they produce children with SCD.

A child should know his or her genotype right from primary school. The genotype is the set of genes in the cells of every living organism which is responsible for a particular trait or characteristics. Last week, while presenting his Inaugural Lecture entitled: "Human Unique Blood Cells and Consequences", at the Main Bowl of the University of Lagos, Akoka, Lagos, Kehinde observed that, Nigeria being the most populous black nation in the world, unfortunately, has the highest incidence of SCD in the world.

"It is estimated that around 2 percent of new borns in Nigeria are affected by sickle cell anaemia giving a total of at least 150,000 affected children born every year in Nigeria alone. "Sickle Cell Disease causes approximately 8 percent of all infant deaths per year. The carrier of haemoglobin S frequency is between 10 to 40 percent with an average of 25 percent in Nigeria. That means the sickle cell trait carrier population is over 50 million. Thus, one person out of every four persons has HbS."

Overlooked epidemic: Further, Kehinde said if an inherited disorder can be described as an epidemic, then sickle cell anaemia in Nigerian would eminently qualify for that description.

"So it is an epidemic that has been over looked. People should know their genotype long before they get married and not just before or after marriage, because once they are about to settle down, there is little that they can be told again to change their perception. They will run away from you and settle down somewhere else.

Explaining that SCD is inherited and not acquired, the physician noted: "When AA marries AA, all their children will be AA. If AA marries AS, there is 50 percent chance that a child will be AA and 50 percent chance that a child will be AS.Fpr children that inherit the sickle haemoglobin gene from one parent and a normal gene from the other parent have sickle cell trait. People who have sickle cell trait usually have few, if any, symptoms and live normal lives."

Selection and consequences

"When AA marries AA, all their children will be AA. If AA marries AS, there is 50 percent chance that a child will be AA and 50 percent chance that a child will be AS. When AS marries AS, there is 50 percent chance the child will be AS, 25 percent chance the child will be AA and 25 percent chance the child will be SS."

"If a couple with AA and SS genotypes marry, all of their children will be AS. When AS marries SS, it is 50 percent chance their child will be AS and 50 percent chance the child will be SS. When SS marries SS, all their children will be SS."

The life journey of a person with SCD can be troublesome at times with occurrence of bone pains due to sickling and haemolysis so that the red cell lives only for about 30 days or less rather than for about 120 days (which is normal) as a result of prevailing unfavourable environment such as dehydration, infection, emotional stress, strenuous physical exercise, very cold weather, etc.

The red blood cells are more fragile and more readily scavenged from the circulation, contributing to the chronic anaemia. Sometimes sickle cell crises occur spontaneously due to no identifiable risk factor. They have acute vasoocclusion events, chronic haemolytic anaemia and organ dysfunction due to repeated sickling episodes. Reduced flow and oxygen supply cause pain and lead to rapid destruction of blood cells.

Wrong management: Sickle cell pain crisis is a medical emergency in Nigeria and when we assessed the management of SCD pain crises in adults by medical practitioners in Nigeria, in a cross sectional survey of 174 medical practitioners, we found that 70 to 80 percent of these doctors were giving appropriate strength of analgesics for appropriate severity in pain.

"Thirty two of 163 would however not prescribe narcotic analgesics even in severe pain rises, for various reasons. However, 38 of 174 would give inadequate quantity of fluid and 18 of 124 will not give antibiotic even in the presence of markedly elevated white blood cell count. 45 of 90 will give antimalaria drugs routinely.

Others will give antimalaria drugs only if there is fever. "None of the doctors will insist on a laboratory menstruation of malaria parasitaemia before giving anti-malaria drugs. Although, 70 to 80 percent of doctors manage pain crises appropriately, it would be desired that all doctors manage sickle cell pain crises appropriately

AllAfrica.