Klinefelter Syndrome

The most common sex chromosome anomaly in males (47,XXY).

Written by: Saygı Hospital Health Guide Editorial Board

Last updated: June 10, 2026

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Endokrinoloji department. Book Appointment →

What is Klinefelter Syndrome?

Klinefelter syndrome (KS) is the most common sex chromosome anomaly in males, occurring in 1 of every 500-1000 male births. The karyotype is generally 47,XXY, with rarer 48,XXXY or mosaic forms.

The disease is characterized by primary testicular failure with consequences of androgen deficiency including small testes, gynecomastia, decreased muscle mass, tall stature, infertility, and learning difficulties.

Early diagnosis and testosterone replacement therapy positively affect metabolic and psychological health. For fertility, ICSI with TESE (testicular sperm extraction) can be performed.

Symptoms

Small and firm testes

Gynecomastia

Tall stature and long extremities

Decreased body and facial hair

Decreased muscle mass and strength

Infertility (azoospermia)

Learning difficulties and speech delay

Risk Factors

Advanced maternal age (slight increase)

Meiotic nondisjunction

History of previous pregnancy with chromosomal anomaly

No known ethnic/geographic predisposition

Familial clustering is rare

Random events

Detection through prenatal screening

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

Pubertal delay in adolescence
Infertility evaluation
Small testes and gynecomastia
Learning difficulties and social adjustment problems
When low testosterone is detected

Treatment Methods

Testosterone replacement therapy (initiation at puberty recommended)

TESE-ICSI for fertility

Surgery or aesthetic approach for gynecomastia

Osteoporosis prophylaxis and calcium/vitamin D

Psychological and educational support

Lifelong multidisciplinary follow-up

Which Department to Visit?

You can visit our Endokrinoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

Learn About Endokrinoloji Department

Let us help you

You can make an appointment with our specialists or contact us for your concerns.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.