user15223: If a Woman Grandmaster (WGM) transitions to a man, does he retain the WGM title?
Related, but not part of this question: Are there any rules for transgender players in chess? which establishes that if a male GM transitions to a woman, she does not instantly acquire the WGM title, but says nothing about the reverse situation.

user20721: FIDE has not ruled on that possibility yet.  No national federation is known to have ruled on that yet. 
A related case is going to the US Supreme court that might influence how others do eventually rule should such an event ever actually happen. 

15223: <p>If a Woman Grandmaster (WGM) transitions to a man, does he retain the WGM title?</p>

<p>Related, but not part of this question: <a href="https://chess.stackexchange.com/questions/24851/are-there-any-rules-for-transgender-players-in-chess">Are there any rules for transgender players in chess?</a> which establishes that if a male GM transitions to a woman, she does not instantly acquire the WGM title, but says nothing about the reverse situation.</p>
 20721: <p>FIDE has not ruled on that possibility yet.  No national federation is known to have ruled on that yet. </p>

<p>A related case is going to the US Supreme court that might influence how others do eventually rule should such an event ever actually happen. </p>
