Tetrasomy X

Tetrasomy X, XXXX syndrome, quadruple X, or 48,XXXX is an intersex trait that only occurs in AFAB individuals, in which they are born with four X chromosones rather than only the expected two. It appears to be rare, as approximately 100 cases have been reported worldwide, however there may be unspoken cases of the past, as people with this condition can usually function decently well, despite the physical abnormalities that co-side this condition.

The traits that usually come along with this condition is often very similar to traits within the Triple X Syndrome. They often are born with epicanthal folds, flat nasal bridges, a small mouth or underdeveloped face, delayed or absent teeth, enamel defects, joint and muscle tone abnormalities, spine and hip abnormalities, and are often taller than average.They also have an abnormal nervous system, abnormal hearing/vision, abnormal circulatory systems, and abnormal kidneys.

About 50% of patients undergo puberty normally, whereas the other 50% experiences no puberty, partial puberty without secondary sexual characteristics, or complete puberty with menstrual irregularities and/or early menopause (possibly as early as the teens). They are usually able to get pregnant and healthily deliver.

Ones with this condition often experience mild delays in the areas of speech development and articulation, language expression and understanding, and reading skills. Delays in motor development are also present, with walking ages ranging from 16 months to 4.5 years. Despite this fact, brain scans haven't shown any abnormalities within the brain of these individuals.

History
Tetrasomy X was first described in 1961.

Resources

 * https://en.wikipedia.org/wiki/Tetrasomy_X