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Genetic disorders
By
DR-SHOROQ AL-TEMIMI
ASSISTANT PROFESSOR
FOR HISTOPATHOLOGY
Cytogenetic disorders involving sex
chromosomes
1-Klinefelter syndrome
2-Turner syndrome
Klinefelter syndrome
It is best defined as male hypogonadism that occurs
when there are two or more X chromosomes and at
least one Y chromosome .
This complement results from nondisjunction during
the meiotic division in one of the parents .
Clinical features include:-Patient is tall (mostly for the lower
segment)
- Gynecomastia
-Wide hips
-Lack of secondary sexual
characteristics as deep voice , beard and
male distribution of pubic hair .
-Eunuchoid appearance
- Small atrophic testes and small penis
-Male infertility
-I.Q may be lower than normal
Patients with Klinefelter syndrome have a higher risk
for breast cancer (20 times more common than in
normal males).
It can rarely diagnosed before puberty because
testicular abnormality does not develop before early
puberty .
Diagnostic methods:
Serum examination
The serum testosterone levels are
lower than normal, and serum
gonadotropin(FSH,LH) levels and
estradiol levels are elevated.
Seminal examination
Sperm count is zero .
Ultrasound examination
Small atrophic testes and small penis
Histopathological examination
1-The testicular tubules are totally atrophied
and replaced by pink hyaline collagenous
material .
 Klinefelter syndrome is the most common
causes of male hypogonadism ,reduced
spermatogenesis and male infertility.
2- barr body(darkly staining small mass in
contact with the nuclear membrane of
interphase nucleus )
 Barr bodyies are present in all somatic
cells of normal females, e.g in smears of
buccal squamous epithelial cells .
Karyotyping
-Most of cases (90%) associated with
47XXY
result from Non-disjunction
during meiotic division in one of parents .
Approximately 10% of patients show
mosaic patterns, including :
- 46,XY/47,XXY
- 47,XXY/48,XXXY
Thank you

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