Yes, it is possible for a girl to have XY chromosomes. This can occur in cases of Swyer syndrome and androgen insensitivity syndrome, which are both classified as disorders of sex development (DSD). These conditions affect the development of sex characteristics and result in individuals having a chromosomal makeup that typically corresponds to one gender but outwardly presenting as another.
Swyer syndrome is a rare genetic disorder where individuals with XY chromosomes develop as female externally with functional female genitalia, including a vagina, uterus, and ovaries. Despite the presence of the Y chromosome, the body fails to respond to the testosterone produced, leading to female development.
Androgen insensitivity syndrome is another condition where individuals with XY chromosomes have complete or partial insensitivity to androgens, including testosterone. This can lead to a range of phenotypic presentations, from a completely female appearance to a more ambiguous one with partially developed male genitalia.
In these cases, the individual's gender identity and expression are independent of their chromosomal makeup. While having XY chromosomes is typically associated with male development, it doesn't dictate a person's gender.
It is important to note: These conditions are not diseases, but rather variations in sexual development.