Testicular Feminization Syndrome (TFS), an X-linked recessive trait
TFS is associated with an
Androgen Receptor
locus on the long arm of the X chromosome (Xq11-q12).
The individuals have the XY karyotype typical of males, but develop physically and
psycho-sexually as typical females. Development of some secondary sex
characteristics (e.g.,
enlargement of the breasts) may be unimpaired, but axillary
and pubic
hair are typically absent. Individuals with TFS
are often diagnosed
only when they fail to menstruate at puberty. TFS
appears to be due to an inability of tissues to respond
to androgen. Persons with TFS are invariably sterile, with a blind
vagina, underdeveloped uterus, and sometimes rudimentary
testes. Consequently, the TFS
allele is not passed on by XY "male" individuals, but by their
asymptomatic heterozygous XX sisters.