Finding the Genotype of an Unborn Baby: A Nigerian consultant foetal medicine says it is important for pregnant women to go for early detection of genetic disorders - Health Article

A Nigerian consultant foetal medicine and genetics specialist with the Lagos State University Teaching Hospital in the obstetrics and gynaecology department, says it is important for pregnant women to go for early detection of genetic and non genetic disorders in foetus.

Dr Oloyede identified some of the genetic problems to be genotype related. A blood genotype is different from a blood group because genotype has to do with the genes. Most people have a blood genotype called AA. Those who inherit an A gene from one parent and S gene from the other parent have an AS blood genotype. People with AS blood do not have sickle-cell anemia, but they can pass the disorder on to their offspring. People who inherit S gene from one parent and another S gene from the other parent have an SS blood genotype, the genotype of sickle-cell anemia.

The medical experts asserted that for a child to inherit SS-genotype, he or she must inherit the defective S gene from each parent. Just as it takes two people to have a baby, it takes two people to pass on sickle-cell anaemia. Usually, the disorder is passed on when both parents have AS type blood. When a person with AS-type blood marries another person with AS type blood, there is a 1 in 4 chance that any child born to them will have SS-type blood.

Recent data released by the World Health Organisation (WHO) reveal that averages of 150,000 infants are born with sickle cell disease in Nigeria. The country ranks first as the sickle cell endemic country in the world with an annual infant death of 100,000, representing 8 per cent of infant mortality in the country. This high frequency of sickle cell cases in the country, calls for measures targeted at evolving strategies that will keep the disorder in check.

Dr Oloyede said that sickle-cell anaemia can be prevented. "Foetal medicine has made it possible to diagnose a foetus with the SS genotype as early as eleven weeks of the pregnancy. It is wise for couples to find out blood genotype long before they consider marriage. This can be done by a blood test. People who have AA blood can be assured that none of their children will develop sickle-cell anemia, no matter whom they marry.

Those who have AS blood should understand that if they marry a person who also has AS blood, they run a high risk of producing a child that will have sickle-cell anemia. If they find out that both of them have the AS genotype, they can either decide to break the relationship or still go ahead with their marriage plans, only they must undergo prenatal diagnosis under a fetal medicine specialist to determine if the baby got the SS gene or not and then take a decision whether to keep the baby or not."

According to Dr Oloyede, experience has clearly shown that genetic counselling coupled with the offer of prenatal diagnosis can lead to a large-scale of reduction in births of affected children. However, prenatal diagnosis can raise ethical questions which differ from one culture to another.