followed up twenty-six years later in her late fifties, by which time she had left the institution and was living semi-independently with her sister; she was in good physical health, had experienced menarche and menopause at typical ages (14 and 50), and showed no signs of cognitive decline. much of the medical literature for tetrasomy x dates to the 1960s and 1970s, an era of particular interest in and research on sex chromosome aneuploidy. early reports were frequently discovered during chromosome screenings in institutions for the intellectually disabled. the early preference for diagnosis of sex chromosome aneuploidy in selected samples, such as institution residents and prisoners, led to a biased perspective on the conditions that painted an unduly negative portrait of their phenotypes and prognoses. further research on sex chromosome aneuploidy via unselected samples such as newborn screening allowed for major conditions such as xyy syndrome, klinefelter syndrome, and trisomy x to be re-defined by more representative phenotypes; however, rarer conditions such as tetrasomy x were not ascertained in any such studies, and therefore the medical literature continues to describe cases that were diagnosed due to developmental or behavioural issues. aspects of the early studies remain accepted; a 1969 proposal that each supernumerary x chromosome reduces iq by an average of 15 points is still used as a rule of thumb. sex chromosome tetrasomy and pentasomy conditions have consistently received little attention compared to the more common trisomy conditions. research into conditions such as tetrasomy x has been stymied by biased samples, outdated information, and a lack of publications above the case report level. dedicated patient and family support groups, such as unique and the tetrasomy and pentasomy x support group, began to appear online in the early 2000s. a patient registry in the united kingdom was established in 2004, amidst concerns that little serious research had been conducted on tetrasomy x for many years. diagnosis of sex chromosome aneuploidies is increasing, as is the number of supports available for families. the rarity of and variation in tetrasomy x limits the amount of specific support available, but major chromosome disorder organizations serve the condition and have members who are or are associates of people with it. notes 'karyotype' as a term has multiple meanings, all of which are used here. it may refer to a person's chromosome complement, to the test used to discern said chromosome complement, or to an image of chromosomes ascertained via such a test. aneuploidy is the presence of too many or too few chromosomes in a cell. male phenotypes, innate or induced, with forms of x chromosome polysomy that are usually phenotypically female do occur. for trisomy x, a trans man and several men with sex reversal have been recorded.