The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.
|Signs and Symptoms||Approximate number of patients (when available)|
|Abnormality of chromosome segregation||90%|
|Disproportionate tall stature||90%|
|Neurological speech impairment||90%|
|Abnormal hair quantity||50%|
|Abnormality of movement||50%|
|Clinodactyly of the 5th finger||50%|
|Hypoplasia of penis||50%|
|Reduced bone mineral density||50%|
|Single transverse palmar crease||50%|
|Abnormality of calvarial morphology||7.5%|
|Abnormality of the mitral valve||7.5%|
|Type II diabetes mellitus||7.5%|
Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.
Nonprofit support and advocacy groups bring together patients, families, medical professionals, and researchers. These groups often raise awareness, provide support, and develop patient-centered information. Many are the driving force behind research for better treatments and possible cures. They can direct people to research, resources, and services. Many groups also have experts who serve as medical advisors. Visit their website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.
Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.
These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.
GARD Information Navigator
May 10, 2016
XXY/Klinefelter Syndrome in 2000: Expanding the Phenotype and Identifying New Research Directions
Thursday, August 31, 2000 -
Wednesday, August 30, 2000
Location: NIH Campus, Bethesda, MD
Description: The clinical and research objectives of this conference were to summarize current knowledge concerning the incidence of Klinefelter syndrome and its genetic (cytologic) basis, clarifying the role X-inactivation plays in the widely varied phenotype; summarize the spectrum of clinical features in XXY Klinefelter syndrome—reproductive dysfunction, structural anomalies, and neurologic/cognitive/behavioral dysfunction; review current treatment and management of hormonal deficiency, infertility, and neurologic/behavioral perturbation; summarize current beliefs concerning the biologic basis of functional defects; and delineate those new research areas that would benefit from more focused attention.
Contact: Dr. Felix de la Cruz(301) 496-1383
Co-funding Institute(s): National Institute of Child Health and Human Development
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I have recently been diagnosed with mosaic Klinefelter syndrome and I am trying to find out what the frequency is. See answer
I have Klinefelter syndrome and I was wondering if weight gain is a common problem. Are there studies with ideas of how I could lose the extra weight. See answer
My son is 15 years old and he was diagnosed with KS almost 2 years ago. He is starting to have some emotional problems. He also struggles with suicidal thoughts. Is this normal for someone his age with KS and also should he be taking a hormone replacement at his age? See answer
How many people tend to get this disease? See answer
My husband has Klinefelter syndrome and we were hoping to go through the ICSI/IVF treatment but we wanted to know if we were successful with the pregnancy with a boy would the boy baby also have Klinefelter syndrome because the father has it? See answer
If a woman has a XXY karyotype, does this mean that she has Klinefelter syndrome? See answer
We have just been told that our 2.5 year old grandson has Klinefelter syndrome. We know very little about this condition and how it will affect him and his family in the future. Where can we find additional information? How can we find a health professional to discuss this in more detail? See answer
My son has Klinefelter syndrome. I am aware that he may need testosterone replacement therapy (TRT) when he reaches puberty. For how long is TRT usually done? See answer
Klinefelter syndrome can be caused by nondisjunction. What increases the risk of males or females to have nondisjunction during meiosis? What research is currently underway for Klinefelter syndrome? See answer
My husband has Klinefelter syndrome. I have read a lot of things about this syndrome, but I want to know more about the future. He is 33-years-old, and he didn't take any medication for Klinefelter syndrome in the past. What is the chance of him becoming a father? See answer