KLINEFELTER
SYNDROME
TABLE OF CONTENTS
Description and History 1
Genetic Basis 2
Inheritance Pattern 3
Prevalence 4
Symptoms and Effects 5-7
Diagnosis and Treatment 8-10
Research and Development 11-12
DESCRIPTION:
KLINEFELTER
SYNDROME
Klinefelter Syndrome manifests in males with a range
of symptoms, and diagnostic evaluation is often
prompted by common indicators such as
hypogonadism, gynecomastia, and infertility (Defendi,
G., 2022).
Individuals with Klinefelter Syndrome may experience
reduced muscle mass, decreased body and facial hair,
and enlarged breast tissue (Utiger, R., 2024).
1
HISTORY
It was first described in 1942 by the American
physician Dr. Harry Klinefelter.
Dr. Klinefelter's observations laid the foundation for
understanding the characteristics associated with the
syndrome, including tall stature, small testes,
gynecomastia, and azzoospermia (Los, E., 2023).
It was not until 1959 that a specific chromosomal
abnormality was identified in connection with
Klinefelter Syndrome.
British researcher Patricia A. Jacobs and her
colleagues played a pivotal role in elucidating the
chromosomal aspect of the syndrome, marking a
significant breakthrough in its understanding. DR. HARRY KLINEFELTER
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TABLE OF CONTENTS
Description and History 1
Genetic Basis 2
Inheritance Pattern 3
Prevalence 4
Symptoms and Effects 5-7
Diagnosis and Treatment 8-10
Research and Development 11-12
GENETIC BASIS
Chromosomes are bundles present in all cells of the body including two
categories known as sex chromosomes, which ascertain the genetic sex of an
individual. These chromosomes are labeled as X or Y. The X chromosome is not
exclusively associated with females and is present in both genders. While the
presence of a Y chromosome indicates male gender.
In Klinefelter Syndrome, the additional X chromosome is caused by the
occurrence of nondisjunction, where chromosomes fail to separate at cell division.
A cell with an extra X chromosome that is fertilized will result in a chromosome
pattern of XXY rather than XY, leading to Klinefelter syndrome after conception.
2
GENETIC BASIS
Female (XX) Male (XY) Male - KS (XXY)
In Klinefelter syndrome, a male is born with an additional X
chromosome (XXY). This interferes with the overall development of the
male body, resulting in abnormalities brought on by the condition.
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TABLE OF CONTENTS
Description and History 1
Genetic Basis 2
Inheritance Pattern 3
Prevalence 4
Symptoms and Effects 5-7
Diagnosis and Treatment 8-10
Research and Development 11-12
INHERITANCE
PATTERN
Contrary to direct inheritance, the
syndrome results from a random
genetic error during the formation of
reproductive cells of either parents.
This error is known as nondisjunction,
which disrupts the normal distribution
of X chromosome, leading to the
occurrence of an additional X
chromosome. However, this process
occurs randomly and does not follow
a specific genetic inheritance pattern.
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TABLE OF CONTENTS
Description and History 1
Genetic Basis 2
Inheritance Pattern 3
Prevalence 4
Symptoms and Effects 5-7
Diagnosis and Treatment 8-10
Research and Development 11-12
PREVALENCE
Several studies converge on the prevalence of Klinefelter Syndrome (KS),
indicating its effects in approximately 1 in every 500 to 1000 newborn males,
making it the most common chromosomal disorder. However, a significant
percentage, roughly 70-80%, of individuals with Klinefelter Syndrome are
unaware that they have the particular disorder.
Risk Factor:
Klinefelter syndrome is not caused by parental behavior or choices. Instead, it
arises from a random genetic event, specifically a random error in cell division
during the formation of a parent's reproductive cells. While there may be a slightly
elevated risk for older mothers, the primary cause remains genetic rather than
environmental or behavioral.
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TABLE OF CONTENTS
Description and History 1
Genetic Basis 2
Inheritance Pattern 3
Prevalence 4
Symptoms and Effects 5-7
Diagnosis and Treatment 8-10
Research and Development 11-12
SYMPTOMS BABIES:
Babies born with Klinefelter
syndrome are more likely to Hypotonia (low muscle tone)
have these symptoms. Delay in speaking
These symptoms may be Quiet, docile personality
noticeable, but people are
Problems at birth, such as testicles that
unaware of why they are
present. haven’t descended into scrotum.
Babies are referred to as 0–3
years of age.
5
BOYS AND TEENAGERS: SYMPTOMS
Taller than average stature Males between the ages of 4
Longer legs, shorter torso and broader hips compared and 17 show these
with other boys.
symptoms of the disorder.
Absent, delayed or incomplete puberty
After puberty, less muscular bodies and less facial and
body hair compared with other teens These symptoms affect the
Small, firm testicles patient’s psychological well-
Small penis being, especially during the
Gynecomastia (enlarged breast tissue) teenage years.
Weak bones
Low energy levels
Shyness
Difficulty expressing feelings or socializing
Dyslexia
Attention problems
6
SYMPTOMS MEN:
Adults and seniors that range in Weak bones
age from 18 and above show
symptoms that could affect their Decreased facial and body hair
social and emotional status.
Gynaecomastia
Having these symptoms also Hypogonadism (low production of
affects a male’s low
testosterone)
testosterone level, which could
lead to erectile dysfunction and Small testicles and penis
low sexual drive.
Taller than average stature
Men with KS are vulnerable to
infertility due to the abnormalities
of the testicles.
7
7
Difficulty in body coordination
Children with Klinefelter syndrome may have difficulty in
coordinating their body movements due to hypotonia or low
muscle tone.
Problems with reading, writing, spelling or maths
As caused by dyslexia, affected individuals have learning
disabilities and delays.
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Infertility
This is due to the abnormal development of the testicles, causing
reduced fertility.
Decreased sex drive and erectile dysfunction
Because of hypogonadism or the low production of testosterone,
men are prone to erectile dysfunction and low sex drive.
Social and emotional effects
Klinefelter syndrome can have effects of social and emotional barriers.
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TABLE OF CONTENTS
Description and History 1
Genetic Basis 2
Inheritance Pattern 3
Prevalence 4
Symptoms and Effects 5-7
Diagnosis and Treatment 8-10
Research and Development 11-12
DIAGNOSIS:
Hormone testing Chromosome analysis
Also known as karyotyping, plays a
It is a crucial method for assessing
vital role in identifying genetic disorders
hormone levels, notably follicle- such as Klinefelter syndrome. This
stimulating hormone (FSH) and procedure involves sampling cells,
testosterone, through blood typically from peripheral blood, which
testing. In Klinefelter syndrome are then cultivated to stimulate cell
patients, there tends to be division. Chromosomes are prepared,
elevated FSH levels and stained, and examined under a
decreased testosterone levels. microscope to create a karyotype, a
visual representation of an individual's
(Moorthy, K. 2018).
chromosomal composition.
8
TREATMENT:
Physical symptoms
Supplemental testosterone intake can:
Supplemental testosterone intake.
Males with Klinefelter syndromes Improve muscle mass
are mostly low on testosterone Deepen Voice
levels. Promote growth of facial and body hair.
Ways to take testosterone: Help the reproductive organs to mature
Injections or shots every 2 to 3 Build and maintain bone strength and
weeks help prevent osteoporosis in later
Pills years
Through the skin, also called Produce a more masculine appearance,
transdermal; current methods which can also help relieve anxiety and
include wearing a testosterone depression
patch or rubbing testosterone gel Increase focus and attention
on the skin.
9
TREATMENT:
Language and Learning
Symptoms
Parents of the males that
Some children with KS may struggle with have Klinefelter Syndrome
language and learning, and early action, have noted that engaging in
including speech therapy and educational
support, can help reduce or eliminate these
low-key levels like karate,
difficulties. swimming, tennis, and golf
a. Physical therapists
b. Occupational therapists
can improve motor skills,
c. Behavioural therapists coordination, and confidence.
d. Mental health therapists or counsellors
e. Family therapists
10
TREATMENT:
Social and Behavioural Symptoms
Social and Behavioural Symptoms can be treated the same way
as Language and Learning Symptoms. Boys that need help with
social skills and interacting in groups, which therapists can
provide. Some schools and health centres offer programs for
this. In adolescence, the lack of body hair can lead to
discomfort, possibly causing depression or behavioural issues.
They may also have questions about masculinity or gender
identity, which can be addressed by consulting a mental health
professional.
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TABLE OF CONTENTS
Description and History 1
Genetic Basis 2
Inheritance Pattern 3
Prevalence 4
Symptoms and Effects 5-7
Diagnosis and Treatment 8-10
Research and Development 11-12
RESEARCH AND DEVELOPMENT
Klinefelter Syndrome, a condition posing diagnostic challenges due to
its unidentifiable symptoms, has prompted collaborative efforts between the
government and healthcare organisations such as the FDA and the NIH.
Recently, a study in KS patients showed that testosterone treatment only
partially corrected the unfavourable muscle/fat ratio, but these findings may
be a result of the insufficient testosterone doses used. Lower levels of
testosterone, free testosterone, and SHBG are found in obese men
compared with nonobese men, but the mechanism for lower testosterone in
obese men remains unclear. In fact, it is still unclear how hypogonadism
leads to abdominal adiposity and how the abdominal adiposity leads to
decreased testosterone production, but both scenarios may be part of a self-
perpetuating vicious circle, the so-called hypogonadal-obesity circle.
11
RESEARCH AND DEVELOPMENTS
Prospective studies in KS are needed to address these issues
and perhaps clarify whether early androgen deficiency predisposes
to the hypogonadal-obese insulin-resistant phenotype of KS, or
whether other factors related to the sex chromosome trisomy are
responsible. Such information will help clinicians decide the optimal
timing and mode of hormone therapy for these patients. Males with
Klinefelter syndrome can be given testosterone, a hormone needed
for sexual development. Testosterone is given by injection or
through a skin patch or gel.
11
RESEARCH AND DEVELOPMENTS
Significant advancements have occurred in recent years,
allowing many individuals diagnosed with Klinefelter
syndrome to access testicular sperm extraction (TESE)
procedures. With a recovery rate of approximately 40%, an
intracytoplasmic sperm injection (ICSI) cycle yields a 43%
pregnancy rate, and a cumulative pregnancy rate of 16% is
achieved through ICSI. Ongoing research aims to elucidate
the factors contributing to testicular dysfunction (Gravholt, C.
H., 2023).
11
RESEARCH AND DEVELOPMENTS
The National Institute of Child Health and Human Development
(NICHD), a component of the U.S. Department of Health and
Human Services and part of the NIH, has been dedicated to
advancing research into various aspects of Klinefelter syndrome
(KS) and its associated symptoms to enhance the well-being of
affected males. Current research efforts supported by NICHD
are delving into the origins of chromosomal abnormalities, the
etiology of symptoms like language impairments and diminished
testosterone levels, as well as interventions aimed at mitigating
or preventing KS symptoms, including infertility (NICHD, 2024).
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REFERENCES
Baxter, R. (2021, August 16). What is Klinefelter Syndrome? How might it affect
sexual health? ISSM.
https://www.issm.info/sexual-health-qa/what-is-klinefelter-syndrome- how-might-it-
affect-sexual
health#:~:text=As%20adults%2C%20individuals%20with%20Klinefelter,or%20other%
20individuals%20with%20penises.
Bonomi, M., Rochira, V., Pasquali, D., Balercia, G., Jannini, E. A., & Ferlin, A. (2016).
Klinefelter syndrome (KS): genetics, clinical phenotype and hypogonadism. Journal
of Endocrinological Investigation, 40(2), 123–134.
https://doi.org/10.1007/s40618-016-0541-6
How many people are affected by or at risk for Klinefelter syndrome (KS)? (2024,
January 9)
https://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/risk
REFERENCES
Klinefelter Syndrome (XXY syndrome). (2017, February 13). WebMD.
https://www.webmd.com/men/klinefelter-syndrome
Klinefelter syndrome - Symptoms and causes - Mayo Clinic. (2019b, September 21).
Mayo Clinic.
https://www.mayoclinic.org/diseases-conditions/klinefelter-syndrome/symptoms-
causes/syc-20353949
Moorthy, K. (2018, April 10). Klinefelter Syndrome [Slide show]. SlideShare.
https://www.slideshare.net/KrishnaMoorthy126/klinefelter-syndrome-93433025?
fbclid=IwAR2Uo-dr_c6JTRXJQLI7Sy9RBtEx7MCeYCG__iU6Q5MTxKtjmH4p8MthWUQ
Ross, J. L. (2021, September). Klinefelter Syndrome. KidsHealth.
https://kidshealth.org/en/parents/klinefelter-
syndrome.html#:~:text=Klinefelter%20syndrome%20is%20not%20caused,reproduct
ive%20cells%20are%20being%20formed.
SHORT QUIZ
QUESTION 1:
(Identification)
The physician who studied and described
Klinefelter Syndrome.
4
QUESTION 2:
(Identification)
The British researcher who elucidate the
chromosomal aspect of the syndrome
along with her colleagues.
4
QUESTION 3:
(True or false)
Klinefelter's Syndrome are usually
present in Females.
4
QUESTION 4:
(True or false)
The testes of people with KS produces less
testosterone.
4
QUESTION 5:
(Multiple Choice)
Which of the following chromosomal combinations
is a characteristic of Klinefelter Syndrome?
a. 46, XY
b. 48, XXYY
c. 45, X
d. 47, XXY
4
KEY TO CORRECTION
1.) Dr. Harry Klinefelter 4.) True
2.) Patricia A. Jacobs or 5.) d. 47, XXY
Patricia Jacobs
3.) False
