Dr Seidu Sweadu writes… Sickle Cell Disease (SCD) is a burden in Ghana

Recent discoveries showed that 2% of new born babies are always affected in our Ghanaian societies. This means that one(1) in every three(3) Ghanaian has haemoglobin S and/or C gene.

The genetic predisposition with an SCD prevalence of 2% in Ghana is reported to be 25%. This simply means in every three(3) Ghanaian new born babies, one has HbAs, HbSS, or HbSC genotype (18, 19) resulting in the 90% – 95% death rate of sickle cell children before the age of five(5).

BLOOD GROUP/TYPE AND CHARACTERISTICS

An individual traits are determined by a combination of alleles on corresponding chromosomes. It can only be determined by biological test. There are four(4) major blood groups of which are A, B, AB ans O with a differential breakdown of eight(kinds namely A+, A-, B+, B-, AB+, AB-, O+ and O-.

Example of genotypes can be genes which may be responsible for traits like a person’s voice, eye color, hair color, leg size and even some diseases or disorders. Genotype are distinguished based on the alleles a person has and there are six(6) types in humans. These are AA, AS, AC, SS, SC, and CC.

Mostly, blood test is done to show whether the A or B traits are present in a blood sample. Blood type (A) individual has at least one copy of the (A) allele but they could also have two copies. Such a person can have genotype AA or AO. AB or O blood type is more informative is more informative when determining the blood group. An individual with blood type AB automatically has both the A and B alleles and therefore it is AB. On the other hand a person with blood type O has neither the A nor B allele, therefore the resultant is OO. The blood type for the genotypes are as follow:

AA  A

AO  A

AB  AB

BO  B

BB  B

OO  O

A person may further understand blood types understand blood types during blood transfusions. In this regard the ABO group system is used to match the blood type of the donor and the recipient. A person with blood type O can donate blood to anyone and therefore is termed as ‘universal donor’. Similarly, an AB blood type can accept blood from all donors and also called ‘universal recipients’. People with type A or B blood group can also receive matching blood or type O only.

IMPORTANCE OF KNOWING ONES GENOTYPE

Blood genotyping is significant when choosing significant when choosing a life partner. This is to avoid compatibility issues that may bring up devastating effects during the period of conception through to delivery. People with sickle cells experience series of mild to severe pains in their body parts where there is the compromisation of the flow of oxygen due to the blockage in the blood vessels. People with genotype AA are safe when marrying individuals of the rest of the genotypes. AA is compatible with AS but AS and AS, AS and AC are very risky because two sickle cells because must avoid conception. Their compatibility chat is as follows:

AA + AA  AA, AA, AA, AA EXCELLENT COMPATIBILITY

AA + AS  AA, AS, AA, AS GOOD COMPATIBILITY

AA + SS  AS, AS, AS, AS FAIR COMPATIBILITY

AA + AC  AA, AA, AA, AC GOOD COMPATIBILITY

AS + AS  AS, AS, AS, SS BAD COMPATIBILITY

AS + SS  AS, SS, SS, SS VERY BAD COMPATIBILITY

AS + AC  AA, AC, AS, SS BAD COMPATIBILITY

SS + SS  SS, SS, SS, SS, DANGEROUS COMPATIBILITY

AC + SS  AS, AS, SS, SS EXTREMELY BAD COMPATIBILITY

AC + AC  AA, AC, AC, SS BAD COMPATIBILITY

GENOTYPE AND PHENOTYPE

The two words might sound the same and related but they mean different things.

Genotypes are genes in the DNA an organism responsible for a particular trait whereas phenotypes are the physical expressions of a particular trait.

Some other differences are as follows:

• phenotypes are characteristics that are seen on the body of an organism whiles genotypes are seen within the chromosome of an organism and can also not be seen.

• Genotypes are inherited from parents to offspring but phenotypes are not inherited

• Phenotype are affected by environmental factors whereas genotypes are not.

• Phenotypes may change during the lifetime of an individual but genotypes remain the same throughout an individual’s life.

• Examples of phenotypes include eye colour, hair texture, blood group whiles genotype has examples like TT as the homozygous allele for height, Tt as the heterozygous allele for height and BB for the homozygous allele for eye colour.

SICKLE CELL GENOTYPE

Sickle cell anaemia is caused by a gene mutation of the red blood cells that makes them to be shaped like the crescent moon. This is an inherited gene from parents to offspring. In this case, If both parents transfer the genes to a child then the child is said to have sickle cell disease but if only one parent passes on the gene then the child is said to have sickle cell traits.

Below are the common sickle cell diseases.

• HAEMOGLOBIN SS This is the most common sickle cell diseases and it is caused by a child inheriting copies of the haemoglobin S from both parents.

• HAEMOGLOBIN SC This happens when a child inherits then a child inherits the C haemoglobin from one parent and S haemoglobin from the other parent.

• HEMOGLOBIN SB+ THALASSEMIA This inhibit a beta-globin gene production and a subsequent reduction in the production of Beta proteins hence reducing the size of the red blood cells.

• HEMOGLOBIN SB 0 THALASSEMIA This is also caused by beta-globin gene but it is sporadic.

ADVICE

Genotypes are very important to humans as they determine ones resistance to disease, reactions to drugs, immunity development, features that shape an individual. Genotypes influence your phenotype Thus having a huge impact on your traits or characteristics. One should therefore make it a point to knowing your type to avoid compatibility issues when choosing a life partner.

Besides love, blood group compatibility between two people is another crucial factor to consider before consenting For marriage. Although these does not affect one’s ability to maintain a happy and healthy marriage, it is important when planning to have children. Difference in blood groups of partners in marriage is not a happiness killer. However, awareness of this may help make an informed decision regarding the recommended medical approaches towards bearing children without genetic anomalies.

DISCLAIMER