20 Facts About Trisomy X

Trisomy X occurs via a process called nondisjunction, in which normal cell division is interrupted and produces gametes with too many or too few chromosomes.

Trisomy X has variable effects, ranging from no symptoms at all to significant disability.

Symptoms associated with trisomy X include tall stature, mild developmental delay, subtle physical and skeletal anomalies, increased rates of mental health concerns, and earlier age of menopause.

The added height in trisomy X is primarily in the limbs, with long legs and a shorter sitting height.

The average age of menopause for women with trisomy X is 45 years, compared to 50 years for women with 46, XX karyotypes.

Neuroimaging in trisomy X demonstrates decreased whole brain volumes, correlated with overall intellectual functioning.

Tremor is reported in approximately a quarter of women with trisomy X and responds to the same treatments as in the general population.

Women with trisomy X are often "late bloomers", experiencing high rates of psychological distress into early adulthood, but by their mid-thirties having stronger interpersonal bonds and healthy relationships.

The study of mental health in trisomy X is complicated by the fact that girls and women who were diagnosed before birth seem to be more mildly affected than those diagnosed after.

The vast majority of cases of trisomy X occur randomly; they have nothing to do with the chromosomes of the parents and little chance of recurring in the family.

Nondisjunction is related to advanced maternal age, and trisomy X specifically appears to have a small but significant maternal age effect.

Chromosome aneuploidies such as trisomy X are diagnosed via karyotype, the process in which chromosomes are tested from blood, bone marrow, amniotic fluid, or placental cells.

Tetrasomy X, characterized by four copies of the X chromosome, has some signs in common with more severe cases of trisomy X Intellectual disability, generally mild, is more frequently seen in the tetrasomy than the trisomy.

Trisomy X said that many girls with this condition are completely normal, and that it is not physically noticeable.

Prognosis of trisomy X is broadly good, with adult independence most often achieved, if delayed.

The limited sample, composed only of women with trisomy X who have come to medical attention, has led to speculation this number is an underestimate.

Early reports of women with trisomy X have since been criticized for a dehumanizing ableist perspective, showing nude photographs of institutionalized women described as "mental deficiency patients".

Descriptions of trisomy X overwhelmingly consider the karyotype from a medical perspective, rather than a sociological or educational one.

Canine trisomy X is thought to be underascertained, as most pet dogs are desexed and so underlying infertility will not be discovered.

Three of the six known cases of canine trisomy X demonstrated behavioural issues such as fearfulness, inciting speculation about a link between the karyotype and psychological concerns as seen in humans with the condition.