GROWTH IN STATURE IN FRAGILE-X FAMILIES - A MIXED LONGITUDINAL-STUDY

The effect of fragile X on growth in stature was estimated in individu als aged 5-20 years from 50 fragile X families. The multivariate norma l model for pedigree analysis was applied to the mixed longitudinal da ta, which varied with regard to intervals between the measurements and their number in individual subjects, totalling 349 measurement data p oints from fragile X families, and 292 data points from unrelated norm al subjects. The results of genetic and regression analysis showed tha t, in fragile X boys and girls, total pubertal height gain is impaired , whereas the rate of growth during the preadolescent period is increa sed, compared with the growth rate of nonfragile X subjects. Moreover, the growth parameters in fragile X males were found to be correlated with the size of CGG trinucleotide expansion. The hypothesis of premat ure activation of the hypothalamo-pituitary gonadal axis is postulated as the cause of growth impairment in fragile X boys and girls, which should be verified by data on the timing of pubertal stages, hormone l evels, and bone maturation. (C) 1995 Wiley Liss, Inc.