Clinical and cytogenetic aspects of X-chromosome deletions

Karyotype/phenotype correlations in six non-mosaic patients with dysgenetic ovaries and partial deletions of the X-chromosome (three patients with short arm, and three with long arm deletions) are presented and the pertinent literature is analysed. It would appear that functioning ovarian tissue is present more often in patients with a short arm deletion than in those with a deleted long arm. This may represent a difference in the strength of two sets of controlling factors, but it can also be related to break point position. This in turn may be misinterpreted due to the difficulty in distinguishing between terminal and interstitial deletions in the long arm. Stature may be a heterochromatic effect, but if specific genetic factors influencing stature exist, then they would appear to be situated mostly on the short arm of the X-chromosome, although some 'statural determinants' occur also on the long arm and could be located rather close to the centromere. Deletions of the short arm of the X-chromosome were almost always associated with some features of the Turner phenotype, and could possibly be related to a gene dosage effect.