Male-determining region SRY on the Y chromosome

Normally, the male-determining Y-specific DNA
sequences (SRY) remain on the Y chromosome
during the homologous pairing and crossingover
during meiosis. However, since the maledetermining
region SRY is located very close to
the pseudoautosomal region (PAR), crossingover
in the PAR border region may result in a
transfer of the SRY region to the X chromosome.
This results in a male individual with an XX
karyotype (XX male). Conversely, if the SRY region
is missing from a Y chromosome, a female
phenotype with XY chromosomes (XY female)
results.