Mention must be made of the 1:2000 girl babies born with TS. Again for reasons unclear, these children are born with an X chromosome either missing entirely or partially missing. Apart from many potential problems, they have non-functioning ovaries, which means no estrogen will ever be produced. So as the child approaches puberty, the lack of secondary sexual characteristics becomes apparent, no breast, thighs etc. develop. She is then given supplemental estrogen to correct this, but no progesterone to balance the estrogen. Unfortunately, under the misguided belief that estrogen prevents osteoporosis, (please refer to the page on osteoporosis), she is often put onto HRT. As TS was first reported as recently as the 1930's, it is possible that environmental poisons are to blame.