It is beneficial to know if mutation is the cause of a particular ailment or an individual carries a mutated gene because it gives a clear direction on what the problem is an how it can be resolve of possible.
We have the sex cell and somatic cells, some mutation affects sex cells, while some somatic cells. If a mysterious affect sex cell there is every possibility of it being inherited by the offspring hence adequate knowledge about a mutant gene being in the body can help guide against some further re-occurence.
Negative effect is fear, it creates fear in an individual who has it.
It can lead to depression when an individual becomes traumatize due to his state.
Yes I think it is beneficial to know whether you carry a mutated gene or not because that affects future offspring and generations. Realizing this can help stop further reoccurence. Overall there are very few negative effects, very rarely does a person get a genetic disorder because of some mutations, in order for that to happen you have to change the protein of the gene but in most cases that is not what happens.
