Genotype testing A valuable blood test before marriage

Introduction

Marriage is a major life decision, and in addition to love and compatibility, many couples today are also considering health factors before tying the knot. One important aspect gaining attention is genotype compatibility, which can have a significant impact on the health of future children. Genotype testing, along with other private blood tests, can give individuals a comprehensive understanding of their health status and aid furture planning. In this blog post, we’ll explore the importance of genotype blood tests for prospective marriages.

What is a genotype?

A genotype refers to an individual’s genetic makeup, specifically the pair of alleles inherited from their parents. These alleles determine various characteristics, including the genetic information related to blood disorders, such as sickle cell disease (SCD) and thalassaemia. In the context of marriage and family planning, knowing your genotype is essential because it can help determine the risk of passing on inherited blood disorders to your children.

The most common genotypes associated with blood disorders are:

• AA: This is the normal genotype.
• AS: This is the carrier state for sickle cell trait. While people with AS typically live normal lives without symptoms, they can pass on the gene to their children.
• SS: This genotype is responsible for sickle cell disease, a serious and lifelong health condition.

When both partners are carriers of the sickle cell trait (AS) or have other concerning genotypes, the likelihood of having children with serious genetic conditions increases significantly. This is why a genotype test is crucial for prospective couples.

What is a genotype blood test?

Every individual has a unique genotype. The genotype is the biological coding which ensures this uniqueness. Genetic testing blood tests analyse a sample of the blood in order to uncover information about an individual’s genetic composition. This involves examination of specific regions of the DNA for any mutations or variations which may indicate a predisposition to certain health conditions.

The importance of Genotype testing

There are typically 5 distinct genotypes. These consist of: AA, AS, AC, SS, and SC. While the first 2 pairs (AA & AS) are normal, AC is rare and the latter two (SS, SC) are irregular and anomalous, commonly causing sickle cell disease.

Sickle cell disease occurs when an individual’s blood cells are shaped in a deformed and abnormal manner, potentially blocking blood flow, causing pain and damage to vital organs. Normally, the red blood cells are round and flexible and can move easily through blood vessels, however, in sickle cell disease, the red blood cells are shaped like sickles. These rigid, sticky sickled cells can get stuck in small blood vessels thereby slowing (or blocking) blood flow and oxygen supply to parts of the body.

A genotype blood test is a simple laboratory test used to determine the specific genetic makeup of an individual’s haemoglobin. The test looks for variations in the genes responsible for producing haemoglobin, the protein in red blood cells that carries oxygen. These variations determine whether someone has a normal haemoglobin genotype, carries a trait, or has a genetic condition.

The most common types of haemoglobin gene variations tested include:

• Normal haemoglobin (AA)
• Sickle cell trait (AS)
• Sickle cell disease (SS)
• Thalassaemia trait (minor)
• Other haemoglobin variants (e.g., AC, SC)

This test allows partners to evaluate the risk of their offspring having sickle cell disease, and provides valuable information to plan and prepare for the future. Sickle cell disease is particularly common in people with an African or Caribbean background.

Why is a genotype blood test important for couples?

For couples planning to have children, knowing their genetic compatibility can help avoid the potential heartache of having a child with a severe blood disorder. Here are a few reasons why genotype tests are vital:

1.     Informed Family Planning: By knowing both partners’ genotypes, couples can make informed decisions about having children. For example, if both partners carry the sickle cell trait (AS), there is a 25% chance with each pregnancy that their child will have sickle cell disease (SS). Knowing this information in advance allows couples to plan accordingly and explore various options.

2.     Reducing the Risk of Genetic Disorders: In the UK, sickle cell disease and thalassaemia are among the most common genetic blood disorders. A genotype test helps identify if both partners are carriers of these conditions, reducing the risk of passing them on to future generations.

3.     Pre-marital Counselling: Many couples may not be fully aware of their genetic risks until they undergo testing. With this information, they can seek genetic counselling, where healthcare professionals explain their options, including IVF with genetic screening or even considering adoption.

4.     Cultural and Community Considerations: In some communities, particularly those with African, Caribbean, Mediterranean, Middle Eastern, and Asian heritage, genetic blood disorders like sickle cell and thalassaemia are more prevalent. As a result, pre-marital genotype testing is common in some cultures to avoid passing on these conditions to children.

The compatibility of genotypes

The AA genotype has the best compatibility ratio. An individual with the AA genotype can choose a life partner from virtually all other genotype categories with an extremely minimal possibility of sickle-celled offspring. The AS genotype is best compatible with the AA. A genotypic pairing of AS with AS or AS with AC poses an increased chance of sickle-celled offspring. Similarly, a pairing between AS and SS or the AC and SS is equally as risky and ill-advised, while a pairing of two sickle-celled individuals will almost certainly result in sickle-celled offspring. 

Helpful for couples and prospective marriage

Blood genotype (yours & that of your partner) is a key component to consider before making the decision on a life partner. It is key because a father and mothers genotype ultimately crosses to determine that of the offspring. Equipping yourself with the right information about genotype compatibility will help you make the best quality of life decision(s) where marriage & conception is concerned. This can help you avert the devastating effects that can ensue from sickle cell disease and by extension improve your quality of life. Additionally, it provides you valuable information about your own health and what you carry.

Conclusion

While love and compatibility are the foundations of any strong marriage, understanding your genetic compatibility is just as important for couples planning to have children. Genotype blood testing offers a simple and effective way to assess the risk of passing on serious genetic conditions like sickle cell disease or thalassaemia. In the UK, this test is readily available and highly recommended for those at risk.

By getting tested, couples can make informed decisions about family planning, reducing the likelihood of passing on genetic blood disorders and ensuring a healthier future for their children. If you’re considering marriage and have concerns about your genotype, it’s always a good idea to speak to a healthcare provider and consider a genotype blood test as part of your pre-marital planning.