We all get chromosomes and genes from our parents and in most cases, due to complexity of genetic procedures in our body, an error may occur.
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One of those errors which affect 1 in 1000 women is an additional X chromosome. So, the baby is born with three X chromosomes instead of two. This syndrome is called trisomy X, triplo X syndrome, XXX syndrome, and 47,XXX syndrome because there is 47th chromosome - an additional X chromosome.
A chromosome is a structure that lives in every body cell (well, almost every because red blood cells don't have any chromosome in it). They are storage of genetic information about our parents - and then consequently about us - and we humans have 23 pairs of chromosomes. Here we are interested in 23rd pair because it determines our sex: one X and one Y chromosome means male, while two X chromosomes means female.
Now, when a person has three X chromosomes that means it's female and there's one X chromosome too many. But nature can go a step further: in some women all body cells have three X chromosomes, and in other just some of the cells have XXX combination. And that very number of X chromosomes determines the consequences and what conditions will appear. It is important here to notice that we are talking about genetic error in true sense of the world - hereditary factor doesn't exist here.
Since there can be, theoretically speaking, just one body cell with XXX combination, several of them, a majority of them, or all of them, it's obvious that effects vary greatly. Some XXX women with triple-X syndrome show no symptoms at all and are absolutely normal, while others have learning difficulties, developmental delay and behavioural problems.
Right after the birth, baby girl with XXX combination develop normally and show no signs of an unusual genetic or other condition. Their weight can be smaller than "normal", but that's a very small difference and not conclusive at all. A lot of girls will grow faster than normal and at the age of eight they will be taller than average girls.
In the serious case, girls with XXX can develop neuromotor problems, learning ability, and impaired psychosocial adaptation. This obviously to co-ordination problems at all levels. Behavioural problems including tantrums, shyness and emotional immaturity are more frequent in girls with XXX chromosomes.
Sexual development is normal and triple-X women are fertile though there is a slight increased risk of sex chromosome changes in their children and there is a test which can confirm this. Girls with triple-X have no increased risk of any diseases during childhood or in adult life.
A XXX syndrome is diagnosed by performing a chromosome analysis of a blood sample and fortunately it can be found during prenatal genetic testing. Unfortunately, that testing is recommended only for people considered high risk, so in most cases it won't be performed.
Since we can't pull out that extra chromosome, the only thing we can do is to treat symptoms. If there is learning a girl will require counselling, just as anyone else with that disability. Neuromotor problems will be treated with exercises and psychologist will treat emotional problems.
In short, it's quite possible to lead a full and normal life despite having this syndrome. That girl just need a little bit more attention, and there's no fear that she is more susceptible to diseases than her friends. ■