I’ve used the phrase homozygous a couple of times before on here but I don’t think I’ve properly explained what it really means in the CF world.
So here’s my kind of 101 on the subject (although please remember I have no medical/scientific background whatsoever, this is just a bit of a reminder of high school genetics to be honest!🙈 🧬And apologies to those who already know this inside out.)
There are over 2,000 known CF mutations. This means there are over 2,000 different ways that the CFTR gene can have mutated. (CFTR stands for cystic fibrosis transmembrane conductance regulator).
If you are a CF carrier you will have one copy of one of the CF mutations - it could be any one of those 2,000 mutations.
In order to have CF you must have 2 mutated copies of the CFTR gene. But they don’t have to be 2 copies of the SAME mutation in order for someone to have CF.
If someone with CF is homozygous then they will have two copies of the same CFTR gene mutation. So their mum and dad must have been carriers of the same mutation.
If someone with CF is heterozygous then they will have 2 different CFTR gene mutations. So mum must have been a carrier of one particular mutation and dad must have been a carrier of a different mutation.
The most common mutation is delta F508. This accounts for approximately 70% of all CF mutations.
Each different ‘combination’ carries different implications for the person with CF. For instance those that are homozygous DF508 tend to be more likely to be pancreatic insufficient.
But then it’s all ‘swings and roundabouts’ because due to the fact that DF508 is the most common mutation, this is where a lot of the drug research and developments in treatments are focused.
So in many ways whilst it means a higher chance of pancreatic insufficiency and other complications, Arlo is lucky to be homozygous DF508 as more drug/treatment options will be available to him. Or as one of our friends said “it’s the connoisseurs CF”!!
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