It is considered a variation of Triple X syndrome.

On average, five to ten girls with triple X syndrome are born in the United States each day.

Females with triple X syndrome have three X chromosomes instead of two.

Thus, Triple X syndrome most often has only mild effects, or has no unusual effects at all.

Triple X syndrome can be diagnosed prenatally through amniocentesis or chorionic villus sampling.

Some females with triple X syndrome have an extra X chromosome in only some of their cells.

Girls with Triple X syndrome are at increased risk of delayed language development, EEG abnormalities, motor-coordination problems and auditory-processing disorders, and scoliosis.

Taurodontism is a condition where the body of the tooth and pulp chamber is enlarged, and is associated with Klinefelter syndrome, Tricho-dento-osseous syndrome, Triple X syndrome, and XYY syndrome.

In some cases, trisomy X occurs during cell division in early embryonic development.

Trisomy X occurs randomly as a result from errors during the division of reproductive cells in one of the parents.

Females with trisomy X have three X chromosomes, for a total of 47 chromosomes per cell.

Normally, females have two X chromosomes; however, females with trisomy X carry three X chromosomes in the nuclei of body cells.

The Focus Foundation's article explaining the phenotype of Trisomy X is available on the National Organization for Rare Disorders (NORD) website.

For people with disorders like trisomy X, where the genotype has three X chromosomes, X-inactivation will inactivate all X chromosomes until there is only one X chromosome active.

Provides support, resources and informational materials to parents of children with triple X syndrome (aka trisomy X or 47, XXX syndrome).

XXX syndrome and XXY syndrome, having an extra X chromosome, are associated with a high frequencies of psychosis.

British pathologist and geneticist Bernard Lennox, the principal consultant on medical terms for the Oxford English Dictionary, suggested the term "XXX syndrome".