Klinefelter and Other X and Y Chromosome Variations Program

The Klinefelter Program at Children’s Hospital of Philadelphia treats children and adolescents who have been diagnosed with Klinefelter syndrome (also known as 47,XXY), a genetic condition in which a boy is born with an extra X chromosome. We also treat children with other X and Y chromosome variations, such as 48,XXXY or 47,XXX. We work with patients and families from infancy through early adulthood, providing multidisciplinary assessment, treatment and care planning — all during a single clinic appointment.

The Klinefelter Program is part of CHOP’s Adrenal and Puberty Center, which has expertise in treating children with an array of conditions that may affect puberty and gonadal function. The Adrenal and Puberty Center is under the Division of Endocrinology and Diabetes.