Critical blood disorders couples should consider

Monday February 22 2021

Richard Nkusa

By Guest Writer

Over the years, parents have been struggling with certain disease conditions, mostly genetic disorders, among their children which impose high financial burden.
Sometimes parents fall victim of these conditions because they are unaware of their own status concerning a particular disorder.
However, the good news is that most of these genetic disorders and incompatibilities can be detected among couples earlier and appropriate medical  interventions implemented.

In the clinical laboratory, there are several screening and molecular tests that can be done to detect the genetic mutations within the genes responsible for these diseases.

However, there are conditions couples should be aware of. These are sickle cell anemia and Rhesus factor incompatibility.
Sickle cell condition is a genetic disease that affects the red blood cells causing them to change from the normal disc and biconcave shape to crescent (sickle-shaped).
 These crescent red blood cells are not efficient in transporting oxygen and cannot easily move through narrow blood vessels causing severe pain and swelling.

The complications of sickle cell disease include severe anemia resulting into jaundice, swelling of the feet and hands (hand-foot syndrome), delayed growth, seizures, among others.  For a child to have sickle cell disease, he/she gets a copy sickle cell gene from both parents. Presence of sickle cell gene is represented by letter “S” and a normal gene is represented by letter “A”.

Therefore a person with sickle cell disease has genotype HbSS, a normal person has genotype HbAA and a person with sickle cell trait (carrier) has genotype HbAS. The problem always arises when both parents have sickle cell traits (carriers) because there is a 25 per cent chance of them giving birth to a child with sickle cell disease (HbSS), 50 per cent chance of giving birth to carriers (HbAS) and only 25 per cent chance of giving birth to a normal child (HbAA). Coincidentally if both parents are sicklers, 100 per cent of children will be sicklers (very rare scenario).

Scientific studies show that up to about 23.9 per cent of population in Uganda have sickle cell traits (carriers) and those with sickle cell diseases constitutes about up to 1.5 per cent in some regions of Uganda.


Sickle cell status of an individual can be determined in the clinical laboratory through, Hemoglobin electrophoresis, screening tests, full blood count and molecular tests, etc all of which requires expertise and well trained laboratory personnel.

Therefore it’s always better for couples to know their sickle cell status and seek appropriate medical advice before having a child.

On the other hand, Rhesus factor incompatibility is not a disease but it occurs due to the variation in the presence of Rhesus antigen (Rh) which is normally present on the surface of the red blood cells.

The Rhesus antigen that is always screened in the laboratory is Rhesus D (RhD) and over 85 per cent of the population are RhD positive. An individual with the RhD antigen present on the surface of red blood cells (RBCs) is termed RhD positive while a person without is termed RhD negative.

The Rhesus negative blood is always incompatible with a Rhesus positive blood. When a Rhesus negative mother conceives the first baby with a Rhesus positive man and the baby happens to be Rhesus positive, there is always no problem for the first pregnancy.

But there is always possibilities of a problem if the blood of the Rhesus positive first baby get into contact with that of the mother (Rhesus negative), the mother’s blood responds by producing antibodies against Rhesus positive blood since it treats it as foreign.

Therefore, there is always a problem concerning subsequent pregnancies when a woman who is Rhesus D negative conceives again with a man who is Rh D positive.

 Richard Nkusa is  a medical laboratory scientist