Do you know anything about this topic on reassignment surgery or sx change? I know somebody going through it and not sure how to handle it?
Yes it is when sexual characteristics are substituted. That is from male to female and vice versa
Do you consider it to be a mental disorder? 
Not at all, this is because it happens other species of animals, we can say it happens in nature
What other species of animals does it happen to. I've never heard of that?
Good question, the fish such as Clownfish and moray eels, gobies and other fish  exhibit this in nature
Wow, I'll have to look that up. Ho do you think one should deal with a close friend or family member that wants to go through this procedure?
Encourage them, It's not a big deal in nature as  alot of species show hermaphroditism, you know what that is right?
No I don't, what is that?
process of changing gender role ("living as a woman" instead of living as a man, or vice versa), including but not necessarily limited to medical procedures.
Natural sex change.
Natural sex change In animals.
Some species exhibit sequential hermaphroditism. In these species, such as many species of coral reef fishes, sex change is a normal anatomical process. Clownfish, wrasses, moray eels, gobies and other fish species are known to change sex, including reproductive functions. A school of clownfish is always
Sex change
Sex change is a process by which a person or animal changes sex – that is, by which female sexual characteristics are substituted for male ones or vice versa. Sex change may occur naturally, as in the case of the sequential hermaphroditism observed in some species. Most commonly, however, the term is used for sex reassignment therapy, including sex reassignment surgery, carried out on humans. It is also sometimes used for the medical procedures applied to intersex people. The term may also be applied to the broader