It should be stressed that Islam wipes out every sin that was committed before conversion. Therefore, there is no question that one who embraces Islam is accepted as a Muslim and nobody has the right to deny him/her the right to be treated so.
Sheikh Muhammad Nur Abdullah, former President of the ISNA (Islamic Society of North America) and member of the Fiqh Council of North America, states: The issue needs some clarification as it involves some details.
1. If the person was born bisexual and there was a medical necessity to do sex change operation to redress the biological imbalance in the body, then it is allowed.
2. If the person was born a man, for instance, but the female hormones are greatly outweighing the male ones, and for health reasons a sex change operation is needed to rectify this deficiency, then it is also allowed.
3. If the person is born normal, but for the sake of “fun” he or she has undergone a sex change operation, then he has committed a major sin that is absolutely unacceptable from the viewpoint of Islam.
however, since Islam does away with everything that went before, if a non-Muslim embraces Islam after he or she has undergone a sex change operation, then definitely we accept him or her as a Muslim. If the sex change operation was done completely that he is no longer a man, then we have no option but to accept her as a woman and deal with her accordingly.