What happens if a mutated gamete (2n) fertilizes a normal one (1n) in humans?

i guess both gametes would have so much fun anyway!

the fetus will not be able to develop and will die in the developmental stages. 3n nuclei disorder can only occur in plants not in animals

Fertilization will occur but the embryo will abort at very early stage of development because pregnancy is maintained by only a 2n fetus. 3n zygote can also be develop if a 1n ova is fertilized by 2 sperms, this is known as polyspermy but this rarely occur and pregnancy is not successful in this case too.

> What happens if this gamete is fertilized (or fertilizes if male gamete) by a normal (1n) gamete?
You get a 3n triploid zygote.> Would the fertilization succeed?
Yes, since fertilization is determined by cell-surface interactions and not by ploidy.  This happens in some plants occasionally.> what disorder would the produced fetus (later on a baby) have?
If we're talking about a plant, you end up with a polyploid plant.
If we're talking about an animal, the most likely result is that development stops and the embryo dies, probably at about the 16-cell stage -- when the embryo's genes are becoming more important to development than the stored maternal mRNA.