I understand mostly about how traits are passed through parents to children, but how does the exact mutation for sickle cell get passed down onto a child? I’m so confused.
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Sickle cell is a genetic trait like any other – it gets passed down the same exact way that a gene for blond hair gets passed down, or a gene for colorblindness, or any number of other traits that we have.
Different versions of a gene are called “alleles,” so for example there are alleles that code for brown eyes, and alleles that code for blue eyes. Sickle cell is one allele of a gene that makes hemoglobin, which in an important protein in our blood – it mutated randomly thousands upon thousands of years ago, and then was copied and passed on just like any other trait. All of us have some mutations in us, some are mostly harmless, some quite harmful. And sickle cell is what’s called a “recessive” allele – if someone receives a “healthy” allele from one parent and a sickle-cell version from the other (a hybrid trait), they’ll have very few problems; because the healthy version can still do its work, it covers up the bad trait for the most part.
The fun part, though, is that people with that sickle cell gene are actually much more resistant to malaria, and even if they get it, they’ll usually have a much more minor case. Which is theorized to be why the disease has stuck around, especially in parts of Africa, the Mediterranean, the Middle East, etc. where malaria has been a big problem. For people in those areas, having the hybrid trait is the best of both worlds – few worries from sickle-cell, and few issues from malaria.
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