Klinefelter Syndrome
What is Klinefelter Syndrome? Klinefelter Syndrome is a chromosomal disorder that occurs when a boy is born with an extra copy of the X chromosome. This genetic condition affects males and is often not diagnosed until adulthood. The condition was identified in 1942 by Henry Klinefelter. The etiology was considered to be due to an unknown endocrine disorder until 1959, when further research studies were done by Jacobs et al. Today, Klinefelter syndrome (KS) refers to a group of chromosomal disorders in which the normal male Karyotype, 46, XY, has at least one extra X chromosome. Read More
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Klinefelter Syndrome
Table of contents
- What is Klinefelter Syndrome?
- Causes
- What are the risk factors of Klinefelter syndrome?
- Symptoms
- How is Klinefelter syndrome diagnosed?
- How is Klinefelter syndrome treated?
- What are the most common complications of Klinefelter syndrome?
- What is the life expectancy of a person diagnosed with Klinefelter syndrome?
- FAQ
What is Klinefelter Syndrome?
Klinefelter Syndrome is a chromosomal disorder that occurs when a boy is born with an extra copy of the X chromosome. This genetic condition affects males and is often not diagnosed until adulthood. The condition was identified in 1942 by Henry Klinefelter. The etiology was considered to be due to an unknown endocrine disorder until 1959, when further research studies were done by Jacobs et al. Today, Klinefelter syndrome (KS) refers to a group of chromosomal disorders in which the normal male Karyotype, 46, XY, has at least one extra X chromosome.
Humans have 46 chromosomes, which include the 2 sex chromosomes, X and Y (fathers have XY, while mothers have XX). A female child will inherit X from the father and X from the mother, thus having an XX genotype. A male child inherits Y from the father and X from the mother, thus having an XY genotype. It is important to note that mothers only pass on X chromosomes to children. So, the father’s contributed chromosome determines the sex of the child (in all normal situations).
Causes
The random genetic error that causes a male to be born with an extra sex chromosome is what results in the Klinefelter syndrome. Although KS is a genetic condition, it is not an inherited condition.
The cause of KS is:
- The presence of an additional copy of the X chromosome within every cell (XXY). The most commonly reported reason.
- A second X chromosome has been added to certain cells
- More than one replica of the X chromosome. However, this is uncommon and can result in an extreme form of KS.
These extra copies of genes on the X chromosomes interfere with male sexual development and fertility, as well as physical activities, language, and behavior.
What are the risk factors of Klinefelter syndrome?
It is linked to a random genetic defect. The risk of the syndrome is not a result of parents’ omission, actions, or inactions. For mothers who are older, the risk is higher, but not by much.
Symptoms
The signs and symptoms of Klinefelter syndrome vary widely among males and by age. It had been observed that:
In babies, signs and symptoms may include:
- Longer than average time to sit up, crawl, walk, and even speak.
- Weak muscles.
- At birth, testicles that haven’t descended into the scrotum.
Boys (including teenagers)
- Smaller penis
- Small firm testicles
- Weak bones (osteoporosis)
- Swollen breast tissue
- Taller than average stature
- Longer legs, shorter torso, and broader hips than normal.
- Absent, delayed, or incomplete puberty.
- Less muscle, less facial, and body hair compared with other teens.
- Always weak
- Shyness or lack of self-esteem.
- Difficulty in expressing thoughts and feelings or socializing.
- Serious challenges in reading, writing, spelling, or mathematics.
Men (adults)
- Absence of sperm or low sperm count.
- Small testicles and penis
- Low libido (low sex drive)
- Weak bones (osteoporosis)
- Reduced facial or body hair
- Exceeds average height
- Less muscular than another man
- Swollen breast tissue
- Extra fat and baglike belly
- Decreased serum testosterone concentrations.
- Increased serum follicle, stimulating hormone, and luteinizing hormone concentrations.
- Diabetes Mellitus.
- Goiter (enlargement of the thyroid gland)
- Various cancers may be prevalent.
How is Klinefelter syndrome diagnosed?
- Physical Examination
During the physical examination, the doctor will ask the patient questions about symptoms and health, including examining the genitals and chest and assessing development and functioning.
- Hormone Testing
This test uses blood and urine samples to reveal abnormal hormone levels.
- Chromosome Analysis
A blood sample is analyzed in the lab to check the shape and number of chromosomes.
- Amniocentesis
Invasive prenatal testing is done on a pregnant woman by removing amniotic fluid from the uterus for testing to confirm the KS status of the unborn baby.
- Routine bone density scanning
Routine bone density scanning is done because patients with androgen deficiency significantly increase the risk of osteopenia and osteoporosis.
- Imaging tests
They include echocardiography (ECG), a test to assess the heart’s function and check for mitral valve prolapse, and radiography to assess bone density and check for dental deformities.
- Histopathological studies
During this examination, the doctor takes a small sample from the testicles to check the germ cell count [1].
How is Klinefelter syndrome treated?
This is a condition that is present at birth (congenital). Since it is a part of a person’s genetic code. There is no absolute treatment available for this condition. However, the symptoms caused by this condition can be managed and minimize their impact on the patient’s condition. The sooner the diagnosis and subsequent treatment, the greater the benefits. Some successful treatments for Klinefelter syndrome based on signs and symptoms may include:
- Testosterone Replacement Therapy (TRT)
This is given (usually at the onset of puberty) to help stimulate changes that normally take place at puberty. These include developing a deeper voice, increasing muscle, and growing facial and body hair. It also improves libido and bone density and reduces osteoporosis, mood, and behavior. It does not prevent infertility.
- Breast Tissue Removal (Mastectomy)
This process removes excess breast tissue from men who develop swollen breasts.
- Fertility Treatment
This gives hope to men who are unable to become a father to children because of the low or no sperm count. Intracytoplasmic sperm injection (ICS) may help remove sperms from the testicle using a biopsy needle and injected directly into the egg.
- Speech and Physical Therapy
Boys who have problems related to speech, language, and muscle weakness benefit from these treatments.
- Educational Evaluation and Support
Boys with Klinefelter syndrome who have difficulty in learning and socializing can benefit from these support services.
- Psychological Counseling
A family therapist, counselor, or psychologist can be a great help in reducing emotional challenges among teenagers, young adults, and men when confronted with worries and mood changes.
What are the most common complications of Klinefelter syndrome?
Klinefelter syndrome may increase of risk of health conditions:
- Social/emotional problems like low self-esteem, emotional immaturity, and impulsiveness.
- Sexual misfits and infertility
- Anxiety and depression
- Osteoporosis
- Heart and blood vessel disease
- Lung disease
- Breast cancers and some others
- Type 2 diabetes
- Hypertension
- Hyperlipidemia (high cholesterol)
- Rheumatoid arthritis.
- Dental problems
- Autism spectrum disorder (ASD)
What is the life expectancy of a person diagnosed with Klinefelter syndrome?
People with Klinefelter syndrome have a normal life expectancy or are very slightly reduced. However, patients who develop secondary diseases such as cancer may have a shorter life span. Klinefelter syndrome was found to be associated with a significant increase in mortality risk of 40%, corresponding to a significantly reduced median survival of 2 to 3 years.
FAQ
Klinefelter syndrome can be found in around one in 500-1000 newborn boys. Women who become pregnant after 35 are more likely to have a boy with this condition than younger ones.
Females cannot have Klinefelter syndrome, and only males are affected. This condition results from a genetic abnormality in which the boy has an extra copy of the X chromosome. Instead of the normal male Karotype, 46, XY, males with Klinefelter syndrome have a 47, XXY pattern.
Klinefelter syndrome has not typically been associated with mental retardation (MR). However, in recent years, a growing body of evidence suggested that Klinefelter boys often experience language deficits and academic challenges.
Males with Klinefelter syndrome variants, who have a higher number of X chromosomes, have an intellectual disability. About 70% of patients have minor developmental and learning disabilities. KS patients are prone to osteoporosis and breaking bones, which might lead to disability.
Klinefelter syndrome is fairly common and affects 1 in 600 men population. Although about 70-80% of men likely do not know they have this condition [2].
It is a condition caused due to random error in genetic code that occurs before birth; hence it cannot be prevented.
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This condition can be detected before birth. Non-invasive prenatal screening of blood is done during pregnancy, and in order to confirm the disorder, invasive prenatal testing such as amniocentesis is done [3].
Klinefelter syndrome is not an inherited condition. Hence it cannot be passed from father to son.
References
1. Wikstrom AM, Dunkel L. Testicular function in Klinefelter syndrome. Horm Res. 2008. 69(6):317-26. [QxMD MEDLINE Link].
2. https://my.clevelandclinic.org/health/diseases/21116-klinefelter-syndrome#diagnosis-and-tests
