Abstract: | In this collaborative study we report on 2 prenatally and 5 postnatally diagnosed cases with a 47,X,i(Xq), Y chromosomal constitution. Excepting tall stature, the 5 adult patients showed all typical manifestations of Klinefelter syndrome. Taken together with previously reported cases, these data suggest that Klinefelter syndrome with isochromosome Xq has a favorable prognosis with normal mental development, and with normal-to-short stature. The prevalence of this Klinefelter variant is calculated to be between 0.3–0.9% in males with X chromosome polysomies. © 1996 Wiley-Liss, Inc. |