The gene that causes sickle cell anaemia actually provides partial immunity to malaria, which is why this gene has not been bred out of the population over time.
Is that why? Or is it just the people with it aren’t sick enough to die before procreating?
An in-law of an ex has it, and regularly spends days in hospital during crises. Without access to a high quality hospital he'd have been dead a long time ago.
The average life expectancy for someone with sickle-cell disease in developed countries is 40-60 years, and serious crises tend to start from childhood.
That said, it's recessive, and so it's likely the reverse of what you think: It's not primarily the people with full-blown disease who contributes most to the long term survival of the trait, but that the trait alone confers fairly significant advantage in regions where Malaria is huge killer mostly without causing health problems. So across the combined set of carriers and those with the full disease, the life expectancy in Malaria stricken areas tends to be higher.
Pattern of change of the prevalence of the trait correlating with changes in prevalence of Malaria has been observed many places. E.g. the prevalence among US black people is significantly lower and dropping than in the areas their ancestors came from.
R | r
+----+----+
R | RR | Rr |
--+---------+
r | Rr | rr |
+---------+
The people who have some malaria resistance are all of the ones with "r". In particular, the "Rr" folks have the resistance, but not the anemia.
So basically, this gene screws over 1/4 of the population and benefits 1/2. In areas with lots of malaria, this tradeoff is worthwhile, evolutionarily speaking.
One of those harsh cases where evolution (if we personify it) does not care about individuals — only the species.
Although sickle cell does seem to be one of the rare cases where they work out.
But practically, it'd be a huge challenge. Nigeria's one of the main victims of malaria and, not by coincidence, one of the main victims of sickle cell. There are IVF clinics in Nigeria, but they're very expensive even before you consider sickle cell testing. It likely wouldn't scale to all of the births per day, and something like a quarter of the country would need it.
But it's not IMPOSSIBLE. You'd need to do maybe 75 or so per day to cover the 25% or so of the country that have the gene and would need it. Hard and expensive and impractical, but perhaps possible?
Prevention is the preferred method of passing this trait on however.
The train doesn't make you immune to malaria but it does increase resistance after infection.
The FDA-approved treatments reactivate the fetal HBB gene in adults and this change in gene expression control effectively prevents SCD.
Very cool and transformative work. Now we have to get the price tag down from seven figures to four or five figures so that it will be used widely. That may be a few decades. Let’s hope that more efficient alternatives are developed soon.