A congenital abnormality in which a sex chromosome is missing. The woman has only one X-chromosome instead of two (or one chromosome and part of the second X-chromosome). This abnormality occurs during, or frequently after, the fertilization of the ovum. Women suffering from this syndrome are frequently short, have a short and wide neck, and the lower arm is at an angle to the upper arm. The development of the breasts is retarded. The ovaries consist only of slivers of tissue, without any ova. There is therefore also no ovulation or menstruation, with resultant infertility. The vagina and uterus are however present. The syndrome is usually recognized at an early age by the outward appearance of the girl. It can be confirmed by scraping cells from the mucous membrane of the cheeks and sending them for karyotype analysis. The treatment consists of administering the sex hormones which are normally produced by the ovary, and possibly also in giving anabolic steroids to stimulate an increase in height.