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?
Well, focusing on the topic at hand,  as the broader process of changing gender role and medical process of surgery not involved