Decoding the Genetics of Sickle Cell Disease

Though they are frequently misunderstood, genes play an important role in our lives. Most people know that they inherit the majority of their physical features from the genes their parents pass down. Eye color, dangling or detached earlobes, and the ability to curl the tongue into a U are all traits our parents give us even before we’re born.

But genes may also dictate the likelihood or presence of a disease. Sickle cell disease (SCD) is one such genetic attribute.

The gene that causes sickle cell disease, or the anemia that results in severe cases, is a mutated blood-based gene.

If a parent is a carrier, meaning that s/he has one mutated and one conventional gene, then there is a 50-50 chance of passing along the mutated section of the gene. If the other parent passes along a blood-based gene with the same or a similar mutation, then the child will have sickle cell disease. If the other parent passes along a healthy gene, the child will be a carrier.

You may be having nightmares of the two-by-two grids for determining genetic probability from  biology class. It’s not as bad as it seems. Think about flipping two coins. “Heads” is the mutated gene; “tails” is the conventional gene. If, and only if, both coins land heads up does the child inherit sickle cell disease. If there are any tails, the child may or may not be a carrier.

This sounds scary because a little math will tell you that one-quarter of everyone should have sickle cell disease. Fortunately, that’s not the case.

If you don’t have the disease, you don’t need to flip the quarter at all, regardless of your partner’s genetic makeup. Or if you like flipping coins, you get a special one that has two tails and no heads If neither you nor your partner has the mutated gene, use those quarters to buy bubble gum. If one of you has the gene and the other has two conventional genes, the carrier should flip. There is a 50% chance that your child will be a carrier, but there is effectively zero chance that he or she will have the disease. If both you and your partner have the mutated gene, now you’re both flipping and hoping not to match heads.

Knowing your genes can save you a lot of worrying later in life. A relatively simple test can be done to establish what traits and diseases should be worried about as you start to procreate.

Click here to read a genetic counselor’s discussion of the importance of genes in our lives.


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