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FedXFtw t1_ivs9vct wrote

Are there any real world cases, be it disorders or syndromes, or just a disease or illness, which cause faulty enzymes which are similar enough, or reactive enough, where their mere existence is harmful to your health? In which case you'd need to both block the production of these AND provide the body with the proper ones


[deleted] t1_ivsbvbe wrote



Zouden t1_ivu5mjs wrote

But that's a recessive disorder, meaning the presence of some mutated protein isn't sufficient to cause disease. I believe /u/FedXFtw is asking about diseases where even some faulty protein is sufficient to cause disease even if healthy proteins are present.

For that I would look at dominant disorders, like those involving structural proteins such as collagen. In Ehlers-Danlos syndrome, a mutation in one copy of a collagen gene is sufficient to weaken the collagen structures.


[deleted] t1_iwb7df8 wrote



Zouden t1_iwb8s6j wrote

All genes are inherited the same way.

The difference between a recessive or dominant disorder is down to the actual function of the protein encoded by the gene in question; this in turn determines whether a loss of one copy of a gene (remember we have two of each) is sufficient to cause a problem. In many cases, losing function of one gene isn't a big deal because we have the other as a backup. Only when you lose two does disease occur. We call that recessive.

With dominant mutations, losing one is enough to be problematic. This is common in genes that encode for structural proteins, where you need every bit to work correctly.

An interesting case is the sickle-cell mutation of the hemoglobin gene. One copy of the mutation confers resistance to malaria, but two copies causes sickle-cell anaemia. The malaria resistance is a dominant trait, while sickle-cell anaemia is recessive.


[deleted] t1_iwcnjys wrote



Zouden t1_iwcp13v wrote

Yes, being dominant or recessive doesn't always correlate with how deleterious the mutation is. I'm not sure what your question is exactly?


hypergol t1_ivsegyu wrote

sure, there are plenty of diseases caused by gain of function (rather than loss of function) mutations. Parkinson’s disease is one: loss of the ASYN gene is pretty much fine, but mutations in the gene cause familial (early onset) Parkinson’s.


DJ_Velveteen t1_ivspoqr wrote

Huntington's, I reckon. Although iirc Huntingtin (the defective protein that kills you) may not be an enzyme and I'm on a phone so it's not easy to check offhand