X-linked recessive genetic disorders are caused by an abnormality on the x-chromosome. Since males (XY) have only one x-chromosome, they develop the disorder. Females (XX), who have two x-chromosomes (one which contains an extra unaffected copy of the gene), have traditionally been deemed to be "just carriers" who are completely unaffected by the disorder. For most x-linked recessive disorders (which in actuality are not truly recessive), this is simply untrue. In addition to the fact that female carriers may pass the disorder along to their offspring, many do develop physical symptoms of the disorder, sometimes severe. Often, however, they fail to connect these symptoms with their carrier status, subjecting themselves to many years of physical problems that they should not have to tolerate.
Being a carrier of an x-linked disorder can be frightening and lonely. Many carriers do not personally know any other carriers (except perhaps in their immediate family), so there isn't really anyone they can talk to who understands how they feel or what it means to be a carrier. Their health care providers may not be very helpful because there are very few medical studies pertaining to female carriers. In addition to suffering anxiety about possibly developing physical symptoms, female carriers may be devastated by the illness or death of a father, brother, or son from the disorder, or worried about their future reproductive options.
There has long been a gender bias in medicine. For decades, patients enrolled in clinical trials were predominantly male. Most of the studies that did include women did not report results by gender. Although this has begun to change in recent years and medicine is recognizing that diseases and treatments affect the sexes differently, there is still a enormous lack of scientific research and understanding when it comes to female carriers of x-linked disorders. For most x-linked disorders, the medical profession is just beginning to recognize that females are not "just carriers." While it is extremely important to continue searching for treatments and cures for males with x-linked disorders, it is also important to study the effect of these disorders on female carriers, so they too have the opportunity to live a full and healthy life.
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