SHAFAQNA – The Grand Ayatollah Sistani answered a question about the sex change.
Question: Is sex change allowed?
The Grand Ayatollah Sistani: If by sex change it means that by operation genital organs of a man is cut and instead urethra and artificial genital organs are made for him, and by injecting hormones, feminine signs like hair loss of the face or appearance of breast happen; or in the case of a woman if it means that man’s genital organs are made for her and by injecting hormones, manly signs like shrinking breast and growth of the hair on the face are made possible; these cases are not real sex change and religious rules applied to him/her do not change, and because in these cases, the genital organs need to be shown and touched; therefore, it is not allowed.
But if it means that the change in genital organs are internal and external which is the main difference between a man and a woman, then in this case and to its limit and without considering some Haram elements, there is no problem in it; but so far this case has not been proved (ascertained) and so far whatever has been accepted is change of appearance which has no effect on the (religious) rules.
Of course it is possible by operating on those who have problems with genital organs to bring out genital organs which were hidden in a man with feminine appearance without having internal genital organs or to cut manly genital organs from a woman who has internal feminine genital organs. And there is no problem in this (type of operation) in its limits which has no connection with sex change, and of course if it is needed that to look or to touch (the parts to be operated) it is only allowed if it is necessary or if by not doing so, difficulties may occur.
Source: PERSIAN SHAFAQNA