Normal growth and normalization of hypergonadotropic hypogonadism in atypical Turner syndrome (45,X/46,XX/47,XXX). Correlation of body height with distribution of cell lines.

A comparison has been made of a case with 45,X/46,XX/47,XXX mosaicism with some 50 cases in the literature. A significant positive correlation was found between height standard deviation scores of mosaic patients from the literature and the frequency of cells with a normal chromosome constitution (n = 21, rs = 0.552, P < 0.01). In contrast, a significant negative correlation was seen between body height and the frequency of cells with a 45,X constitution (n = 21, rs = -0.594, P < 0.01). There was no significant correlation of height standard deviation score with the 47,XXX cell line (n = 21, rs = -0.353). A patient with a rare chromosomal mosaicism (45,X/46,XX/47,XXX) is described. The diagnosis was first made by chromosome analysis in amniotic cells. The patient showed no symptoms suggestive of Turner syndrome and growth followed the 75th height percentile. Basal and gonadotropin-releasing hormone stimulated gonadotropin levels normalized after age 4.8 years and did not subsequently return to hypergonadotropic levels. In blood lymphocytes, there was an increase in the frequency of cells with a normal chromosome constitution over 9 years. This in vivo cell selection is discussed. Chromosome analysis in skin fibroblasts showed the same triple mosaicism with a similar distribution of cell lines as in blood lymphocytes. In conclusion, statistical evidence was demonstrated that the severity of short stature is correlated with the distribution of cell lines in 45,X/46,XX/47,XXX mosaicism. This finding is of importance for the genetic counselling in cases of prenatal diagnosis of mosaic Turner syndrome.