Karyotype/phenotype correlation in females with short stature

We studied 60 females who presented with short stature. The main aim was to determine the effect of karyotype variation on phenotype. A somatic feature score was calculated for each case depending on the presence of 17 clinical somatic changes known to occur in Turner syndrome. Karyotype studies showed the following results: 45,X (n = 22): 46,XX (n = 11); 45,X/46,XX (n = 10); 46,XX/46,Xi(Xq) (n = 4); 46,XX/46,XXq- (n = 3); 46,XX/46,XXp- (n = 2); 46,Xi(Xq) (n = 2); 45,X/46,Xi(Xq) (n = 2); 46,XXp- (n = 1); 46,XX/47,XXX (n = 1); 46,XXq- (n = 1); 45,X/46,X(ry) (n = 1). Karyotype/phenotype correlation showed the gradation of severity of clinical phenotype to be related to the number of X chromosomes. The highest somatic scores and the most severe clinical manifestations were noted in cases of pure 45,X Turner and the mildest in 46,XX/46,XX(str) mosaics or pure 46,XX, including hypergonadotrophic hypogonadism. Our findings revealed a dosage effect of the X chromosome on phenotype, thus confirming that partial X chromosome inactivation modifies somatic and pubertal development. Our results also support both the additive and interactive hypotheses of karyotype/phenotype correlation.