A psychiatric investigation of triple-X chromosome females.

Among recent developments in human chromosome studies a triple-X state has been recognized in females in whom the chromosome number is 47, composed of @ autosomes and 3 X chromosomes (Jacobs et al., 5959). Early surveys of nuclear sex have shown that the triple-X state is a not uncommon chromosomal anomaly. A survey of Edinburgh babies gave a frequency at birth of these abnormal females of 5 . 78/1,000 births (Court Brown, 5962) and by combining data of surveys from Edinburgh (Maclean et al., 5962), Glasgow (Fraser et al., 5960) and Baltimore (Johnston et al., 5965) the estimated frequency of the triple-X state in mental subnormality institutions i@,4.55/5,000 in-patients. The psychological concomitants of the com moner chromosomal abnormalities are well recognized clinical states. Mental subnormality is associated invariably with Mongolism, not infrequently with Klinefelter's syndrome, and may occur with Turner's syndrome. However, the clinical characteristics of the triple-X state are as yet sparsely documented; because it is a rare condition and extensive procedures are necessary for its diagnosis. The available material on triple-X patients does suggest that unlike the autosomal abnormalities a genetic predisposition to intellectual defect is not neces sarily present. The first case described was mentally normal (Jacobs et al., 1959), sub sequent cases have shown varying grades of intellectual subnormality and some, although identified in subnormality institutions, have been thought to have psychological conditions in which intellectual subnormality is not the most prominent feature (Court Brown, 1962). While carrying out cytogenetic procedures in hospitals it appeared to one of us that a signi ficant proportion of known institutionalized triple-X patients might be suffering not from intellectual subnormality, as might be expected, but from psychotic illness. This paper reports the findings of a psy chiatric investigation of 22 triple-X patients in a matched control study.