Is there a way to predict gain-of-function or gain-of-function based on the amino acid change?
I've been using ANNOVAR for variant functional annotation. It has many databases to add commonly used info. These include resources like SIFT or PolyPhen, but those just give pathogenicity scores. Thus, this makes me think this may not be so trivial.
Damn right.
Except for very obvious cases (deletion of a crucial exon, mutation of crucial cysteine) it's rather hard/impossible to predict the functional consequence of e.g. a random missense variant.
I would think that mutation pathogenicity estimates are difficult as well. Not to imply they are easy, but at least there are many attempts (SIFT, PolyPhen, MutationTaster, MutationAssessor, FATHMM, PROVEAN, MetaSVM, MetaLR, VEST, M-CAP, CADD, GERP++, DANN, etc.).