Shox and Awe: A Case of Variant Turner Syndrome with an Unusual Phenotype

Turner syndrome was first described to encompass a shared set of physical features displayed by a subset of female patients including short stature and lack of sexual development. Half of cases are due to complete loss of an X chromosome, while the remainder are due to other alterations of the X chromosome that disrupt genes necessary for normal physical and sexual development. The SHOX gene, located at Xp22.33, is essential for the growth and maturation of bone, while genes on Xq are important for ovarian function. Thus, loss of an X chromosome results in phenotypic short stature and amenorrhea typically seen in Turner syndrome. We present a unique case of Turner syndrome in a 16-year-old girl with primary amenorrhea and above-average height, in which karyotype revealed a derivative X chromosome resulting in partial Xp trisomy and partial Xq monosomy [46,X,der(X)(pter->q21.2::p11.23->pter)]. We hypothesize this unique karyotype explains the atypical phenotypic presentation of this patient.