The Cleveland Clinic Cares for Klinefelter Syndrome and other XY Variations program provides a wide range of support and intervention for individuals with an XY variation syndrome and their families- from prenatal diagnoses, to adolescence, and into young adulthood. We help coordinate access to experts in a variety of medical and psychological disciplines to support these conditions, with our ultimate goal being to help these individuals to lead independent and healthy lives.

Klinefelter syndrome and other XY variations

Humans have 46 chromosome total. Usually males have one copy each of the X and Y sex chromosomes (depicted as 46,XY). However there are several genetic conditions characterized by changes in the number of sex chromosomes in males:

  • Klinefelter Syndrome- one extra copy of an X chromosome (47,XXY)
  • Other disorders of XY chromosomes (including 48,XXXY, 49,XXXXY, etc.)

Klinefelter syndrome and related XY variant syndromes are not uncommon. It is estimated that one in every 500 males are born with one or more extra X chromosomes. Because the signs and symptoms of Klinefelter syndrome are variable and typically are not noted right at birth, many cases go undiagnosed. However, the increased use of prenatal screening and diagnosis has led to earlier diagnoses and better understanding of these conditions.

Klinefelter syndrome and related XY variant syndromes can present with a variety of symptoms, including:

  • Speech delay
  • Learning problems
  • Behavioral, social, or emotional issues
  • Low muscle tone
  • Physical differences, including taller than expected height
  • Born with a smaller penis or testicles not in scrotum
  • Delayed or absent pubertal changes in teenage years
  • Fertility issues
  • Increased risk for other chronic conditions

For a more comprehensive discussion of these conditions please visit the AXYS webpage.



Because of the wide range of symptoms that these conditions may have, care often requires the coordinated efforts of multiple medical and psychological experts in various disciplines. Depending on the individual’s personal needs, he may require the input of some of the following experts/services available in our clinic:

  • Genetics: geneticists and genetic counselors are available to determine if additional genetic testing is appropriate. Providers review inheritance, recurrence risks, and medical management guidelines, as well as assist with identifying resources for families.
  • Pediatric Endocrinology: monitor growth and puberty development. Testosterone treatment is often initiated in the teenage years. Screening and management of other related endocrine conditions as needed.
  • Neurodevelopmental Pediatricians: developmental monitoring and evaluation for infants diagnosed prenatally or in newborn period. May recommend early intervention/behavior therapy, occupational therapy (OT), speech and language therapy (SLP), and/or physical therapy (PT).
  • Neuropsychologist: mental health, IQ, and achievement testing as needed. May provide educational recommendations.
  • Fertility Specialist: can assess for urological concerns and/or discuss fertility options
Our Team

Our Team

Andrea Mucci, MD
Andrea Mucci, MD
Pediatric Endocrinology
Vickie Zurcher, MD
Vickie Zurcher, MD
Lauren Palange | Cleveland Clinic
Lauren Palange, MS, LCG
Genetic Counselor
Sarah Mazzola | Cleveland Clinic
Sarah Mazzola, MS, LCG
Genetic Counselor
Timothy Sullivan, PhD
Timothy Sullivan, PhD
Pediatric Neuropsychology
Mary Wong, MD
Mary Wong, MD
Neurodevelopmental Disabilities
Sumit Parikh, MD
Sumit Parikh, MD
Pediatric Neurology
Audrey Rhee, MD
Audrey Rhee, MD
Pediatric Urology
Sarah Vij, MD
Sarah Vij, MD
Urology & Fertility
Appointments and Locations

Appointments and Locations

Make an Appointment

To schedule a new patient visit, please contact our program coordinator, Stephanie Lemasters, at 216-444-7987. Appointments can be made Monday - Friday, 9 a.m. - 4 p.m.

Alternatively, if an appointment needs to be rescheduled for any reason you can either contact Stephanie at the number listed above, or try one of the following methods:

  • Call: 216.444.9000 or 866.275.7496 (8 a.m. to 5 p.m. weekdays )
  • Online: Send us an email


All of our providers see patients on Main Campus on certain days but the following providers also see patients at other sites, should you prefer to schedule your visits at one of our regional hospitals:

Andrea Mucci, MD – Pediatric Endocrinology

Audrey Rhee, MD – Pediatric Urology

Sarah Vij, MD – Adult Urology/Fertility

Mary Wong, MD – Neurodevelopmental Disabilities

Referrals and Second Opinions

If you are coming to Cleveland Clinic through a referral or second opinion request from an outside hospital, please send the following medical records in advance of your appointment in our clinic:

  • Genetic testing results
  • Most recent progress/office notes
  • Growth charts
  • Recent lab results

The above should be sent to:

Cleveland Clinic Children’s
9500 Euclid Avenue, R30
Cleveland, OH 44195
Attn: Stephanie Lemasters

If you have questions about this process, please contact Stephanie Lemasters at 216.444.7987.

Note: All patients looking to schedule an appointment must have a Cleveland Clinic Medical Record Number (MRN). If you do not have a Cleveland Clinic MRN, please call the appropriate number below and they will be able to assist you in getting your record created.

  • USA: 216.444.5437
  • International (including Canada): 216.444.6404


Additional information and support regarding Klinefelter syndrome and other XY variations: