Transcript Slide 1
Klinefelter Syndrome
KRISTIN CLEMENS PGY 5
ENDOCRINE ROUNDS
JANUARY 30, 2013
Case
20 year old male
Presents to new family doctor for physical
No known medical conditions
Inguinal hernia repair
No medications, no significant family history
Puberty at age 13, tall compared peers
Development seemed to slow
Learning disability, behavioural problems
Didn’t finish high school
Living at home
Physical Exam
Tall, long legs, BMI 30 kg/m2
Normal cardiac, respiratory and abdominal exams
Scant facial and chest hair
Bilaterally small testicles – 4mL
Klinefelter syndrome?
Objectives
To learn about the origin of Klinefelter syndrome
and understand it’s genetics
To review its many clinical manifestations and
associated medical co morbidities
To learn how to optimally manage patients with the
condition
Klinefelter Syndrome
Most common sex chromosome aneuploidy seen in
clinical practice
1 in 500 live male births
Increased maternal age
?Association with paternal age
First described by Klinefelter in 1942
Reports of 9 men with gynecomastia, sparse facial
and body hair, small testes and an inability to
produce sperm
Genetics
Extra X chromosome first documented in 1959
Classically 47 XXY – 89%
48 XXXY among other variants
Non-disjunction – abnormal partitioning of
chromosomes
Non-disjunction:
Meiosis
Abnormal partitioning of chromosomes during
meiosis such that the resultant haploid gametes have
too many or too few chromosomes
Meiosis
Meiotic non-disjunction
Meiosis I
Meiosis II
genetics.thetech.org
53% result from 1st paternal meiotic non disjunction
34% from 1st maternal meiotic non disjunction
9% 2nd meiotic division
Non disjunction:
Mitosis
Mosaic 47 XXY
Mitotic non disjunction within the zygote
10% of cases
Variable phenotype
Typically less severe
Depends on the specific tissues in which an extra X
chromosome is present
If normal karyotype in the testis may have intact
spermatogenesis and fertility
Pathogenesis:
Extra X Chromosome(s)
Genes of X chromosome play an important role in
the sex development in males and females at the
level of the gonad
More than 100 X chromosome genes are expressed
in the testes
Genes on extra X chromosome:
Testicular failure - progressive loss of germ cells,
seminiferous tubule hyalinization and fibrosis
Low testosterone
Progressive hypogonadism
Furthermore…
Androgen receptor gene on X chromosome
Variable CAG repeats on exon 1
Length of the highly polymorphic CAG repeat
inversely related to AR activity
Short lengths more stable with more marked effect of
androgens
Longer lengths less stable- androgen insensitivity
In Klinefelter’s, at least 2 X chromosomes
Shortest CAG repeat is preferentially inactivated –
non-random X chromosome inactivation
Less effective androgen receptor
Further contributes to the phenotype
Clinical Manifestations
Infancy and Childhood
Micropenis
Small testes
Normal surge of testosterone over 1-6 months
Early gonadal dysfunction and decreased fetal
testosterone in utero
Hypospadias
Cryptochordism
Hypotonia
Cleft palate
Inguinal hernia
Hypertelorism
Elbow dysplasia
Clinodactyly
High arched palate
Journal of Pediatrics
Delayed developmental progress
Delayed gross and fine motor skills
Adjustment disorders
Deficits in language and executive function
Dyslexia
ADHD
Emotional difficulties
Pre-puberty may see disproportionate lower
component compared with upper
Tall stature for familial size
Unfused growth plates secondary to androgen
deficiency
Narrow shoulders, broad hips
Puberty
Normal onset of puberty with rise in testosterone,
LH, FSH until about 13 to 14 years or Tanner stage 3
puberty
Slow progression or arrest of pubertal changes
Impaired Leydig cell reserve and low testosterone
levels
Testicles fail to increase in size and become firm due
to a progressive loss of germ cells and seminiferous
tubule hyalinization and fibrosis
Incomplete virilization with AR instability
Gynecomastia
Gynecomastia
15% of estrogen secreted by testes as estradiol or
estrone
Rest from peripheral conversion from testosterone
95% from the testicles
Adipose tissue has P450 aromatase activity important for
transforming androstenedione into estrone
Conversion increases with age and obesity
Science Direct
Breast tissue development
Balance between estrogen and testosterone
Estrogen stimulates the growth and differentiation of
breast epithelium
Androgens inhibit the growth and development of
breast tissue
Why gynecomastia in Klinefelter’s?
High circulating LH levels stimulate aromatase
activity in Leydig cells leading to higher levels of
estradiol relative to testosterone
Low testosterone
Alteration in estrogen to androgen ratio from high
estrogen or low androgen concentrations
Breast tissue enlargement
Adulthood
Signs/symptoms of hypogonadism
Infertility
Gonadal failure and loss of germ cells from tubule
hyalinization and fibrosis of seminiferous tubules
There’s more!
Osteoporosis
Decreased bone mass in 20-50% of patients and
osteoporosis in up to 15%
Low testosterone?
Testosterone aromatized to estrogen which decreases
bone resorption
Also effects osteoblasts directly through the
androgen receptor
Promotes periosteal bone formation and reduces
bone resorption through adult life
Need testosterone to achieve peak bone mass
Ferlin et al 2011
Cross-sectional cohort study
112 treatment naïve KS XXY and 50 aged matched
controls
43% of KS patients had low bone mass
No significant relationship between testosterone,
bone markers (calcium, phosphate, albumin, PTH,
25 hydroxyvitamin D) and bone mass
CAG repeats not different in those with normal and
low bone mass
Likely multifactorial
Other contributors may include abnormal androgen
receptor, X chromosome inactivation, increase fat
mass and reduced muscle mass, low vitamin D levels
Low insulin like factor 3 levels produced by Leydig
cells
Lung pathology
Bronchitis
Bronchiectasis
Unknown pathophysiology
Malignancies
Germ cell tumours
Mediastinal tumours in 8% (50x expected rate)
Relative risk of 67 in cancer registries
Need to consider in those with known Klinefelter’s and
precocious puberty
Non-Hodgkins lymphoma
Acute leukemia
Breast cancer
20 fold increase in breast cancer
Denmark cohort of 832 KS found that 3.7 to 7.5%
had BC
Brinton et al studied 4.5 million men in US Veterans
Affairs and noted 3518 cases of male breast cancer
with 642 in Klinefelters
RR 16.83 (6.81-41.62)
Alteration in endogenous hormone ratios, genetic
predisposition, presence of gynecomastia
Autoimmune conditions
SLE
RA
Cardiovascular anomalies
Mitral valve prolapse
Aortic valvular disease
Berry aneurysms
Varicose vein
Ulcers
Danish registry
Thromobophlebitis and venous thrombosis HR 5.29
(3.29-8.5)
PE HR 3.6 (1.92-6.74)
CAD HR 1.71 (1.28-2.29)
Abnormalities in plasminogen 1, clotting factors,
obesity
Endocrine
Graves disease
Thyroiditis
Dyslipidemia
DMII
DMII
Jiang-Feng et al
Retrospective longitudinal study of 39 men with
Klinefelter’s and 40 with idiopathic
hypogonadotropic hypogonadism
Prevalence of diabetes in KS group was 20.5% and in
the IHH group 5%
Testosterone effect on insulin sensitivity
IM testosterone (approximately 4 years) to keep total
levels <10 nmol/L
?Testosterone effect doesn’t explain whole story
Extra copy of X chromosome leads to decreased
insulin sensitivity or insulin resistance
Autoimmune disease?
Metabolic syndrome, increased weight
Increased truncal fat and waist measurements
during childhood, adolescence and adulthood
Variable presentation
Genetics – the more X chromosomes, the more
severe
CAG length
CAG lengths
Those with short CAG
repeat lengths found to
have more stable
relationships, higher
educational levels,
greater responses to
testosterone treatment
If long CAG and reduced
AR activity, have longer
arms and legs, smaller
testes, lower BMD,
greater degree of
gynecomastia
Diagnosis
Important as under-diagnosed condition
Only 10% diagnosed prior to puberty
Under diagnosed
Variable phenotype
Limited awareness of condition
Reduced physical observations in teens
Diagnosis
Can be informed of the diagnosis by prenatal
screening usually for the detection of Down
syndrome
Karyotype or FISH for an extra X chromosome
Cultured peripheral blood lymphocytes, skin
fibroblasts, testicular tissue if mosaicism is suspected
Other supportive tests
See Barr body (X inactivation)
Subject to false positives and negatives
In adolescence/adulthood
Increased FSH/LH in 80-90%
Hypergonadotropic hypogonadism
Elevated estrogen to testosterone ratio
Low testosterone in 50-75%
May be normal if have increased SHBG
Inhibin B and AMH
Low inhibin B and anti-mullerian hormone
Both Sertoli cell products
Inhibin B is produced the the Sertoli cell in response
to FSH stimulation
Markers of testicular function, may reflect loss of
Sertoli cells
Patient management
Multidisciplinary
Increased mortality and morbidity because of
concomitant diseases
Gynecomastia
Consideration of breast reduction surgery
?Testosterone therapy may lead to regression
Little data on the benefit of aromatase inhibitors and
anti-estrogens on reversal of breast enlargement
Learning Disabilities, Developmental Delay
Social work
Psychology
Speech and behavioural therapy
Physical and occupational therapy
Hypogonadism
Testosterone
Topical for infants with micropenis
Testosterone therapy
When LH and FSH start to rise and low testosterone
documented
Goal of increasing linear growth, secondary sex
characteristics, muscle mass BMD, libido, energy,
body composition
Goal to normalize LH and keep testosterone in
normal range
Life long therapy
Adulthood?
Nielson 1988
Adult KS patients treated with testosterone for 3
years – treatment naive
77% had subjective benefit from therapy
Improved mood, irritability, energy and drive, better
sleep and relationships with others
Bone Health
Other
Annual breast exam
CXR/CT
Echocardiogram
Fertility
Germ cells are depleted at an accelerated rate after
puberty
Maturation arrest of spermatogenesis, clumping of
Leydig cells
Early diagnosis important
Van Saen et al
7 patients with 47 XXY
Followed testosterone, FSH, inhibin B, spermaturia
Testicular biopsy when no increase in testicular
volume, increased FSH or decreased inhibin
6/7 with extensive fibrosis and hyalinization
Spermatogonia in seminiferous tubules with normal
architecture in the youngest men with normal FSH
and inhibin B
Limited experience in banking as <10% diagnosed
prior to puberty
Testicular sperm extraction and ICSI
TSE and ICSI
TSE permits identification of the relatively few
seminiferous tubules that contain active
spermatogenesis and harvesting of sperm from the
small testes of men with Klinefelter’s for use in ICSI
More than 60 cases of success worldwide
Reported pregnancy rates of 50%
Risk of sex chromosome aneuploidy
Genetic counseling
Guidelines?
Take home messages
Most common sex chromosome aneuploidy
Be aware of the diagnosis – patients with KS will
present to different physicians at different ages and
for different reasons
Look for associated conditions
Used team based, multi-disciplinary management
References
Bojesen et al. Klinefelter’s syndrome, DMII and the metabolic syndrome.
Molecular Human Reproduction 2010; 16: 396-401.
Bojesen et al. Klinefelter syndrome. Nature Clinical Practice 2007; 4: 192203.
Endo EXPO Meet the Professor Handbook
Ferlin et al. Bone mass in patients with Klinefelter’s syndrome: role of
testosterone levels and androgen receptor gene CAG polymorphism
Ferlin et al. Osteoporosis in Klinefelter’s syndrome. Molecular Human
Reproduction 2010; 16: 402-410.
Groth et al. Klinefelter’s syndrome: an update. JCEM 2013; 98: 20-30
Jiang-Feng et al. Prevalence and risk factors of diabetes in patients with
Klinefelter’s syndrome. Fertility and Sterility 2012; 98: 1331-1335.
Sokol et al. It’s not all about the testes: medical issues in patients with
Klinefelter’s syndrome. Fertility and Sterility 2012; 98: 261-265
Van Saen et al. Can pubertal boys with Klinefelter’s benefit from sperm
banking? Human Reproduction 2012; 27: 322-330.
Williams Textbook of Endocrinology
Thank you!