Down syndrome,Turner syndrome,Klinefelter syndrome

1. Ge
BHASKAR
GOUDA
Genetic
Disorder
Higher
Secondary
Biology

2. Down syndrome
The most common genetic disorder
in human population is Down
Syndrome.
It was first described by Langdon
Down in 1866.
The estimated frequency at birth is
1/700.

3. Down Syndrome
It is caused by a chromosomal abberation
called aneuploidy type trisomy 21.
The twenty first chromosome is found in
three doses.
So instead of 46 normal diploid becomes
47(2n+1).

5. Down Syndrome
Formation of abnormal gametes in
parents is mainly responsible for
Down’syndrome.
It is due to nondisjunction of homologous
chromosomes during meiosis-1 or
Meiosis-2.

6. Down Syndrome
Egg or Sperm receive one extra 21
chromosome.
Egg(24)+Sperm(23)=Zygote (47).
Egg(23)+Sperm(24)=Zygote (47).

8. Symptoms
Short stature with an epicanthal Fold.
Broad head with round face.
Wide nostril, open mouth and large
tongue with distinct furrows.

9. Symptoms
Stubby hands with simian crease on
the palm.
Hyperflexible joints.
Mental retardation.

10. Diagnosis
Prenatal screening of pregnant woman.
It maybe through ultrasonography.
It maybe through amniocentesis.

13. Chris Burke
A famous American artist
with down syndrome.

14. Turner Syndrome
Turner Syndrome is a genetic disorder
in which female have one X
chromosome instead of Two.
So total number of chromosomes is
45,out of which 44 autosomes and one
X chromosome.

15. Turner Syndrome
It was given by Henry Turner in 1938.
The frequency of birth of such child is
1/2500 living female births.
In the population frequency is 1/5000.

16. Turner Syndrome

17. Turner Syndrome
The condition is an aneuploidy
called monosomy X or 44X.
It comes due to formation of
abnormal gametes due to
nondisjunction during meiosis.

18. Symptoms
Short stature with low set ears.
Webbed Neck.
Shield like chest.
Swollen hands and feet

19. Symptoms
Virtually no ovaries.
Limitted secondary sexual character.
Amenorrhea or no menstruation.

21. Treatment
There's no cure for the condition. But a number
of treatments can help:
 Growth Hormone (GH) either alone or
with other hormone treatment, may
improve growth and will usually increase
final adult height
 Estrogen therapy can be given when a
girl is 12 or 13 years old to stimulate the
development of secondary sexual
characteristics (breast development and
menstrual periods).

22. Klinefelter Syndrome
Klinefelter Syndrome is an abnormal
genetic disorder.
It is caused by the presence of an extra
X chromosome in addition to the
normal male chromosome set of
44XY.So the chromosome set is 44XXY.

23. Klinefelter Syndrome
Autosomes=44
Allosomes=3
XXY
Total
chromosomes=4
7.

24. Klinefelter Syndrome
Frequency of the disease is 1/500
living male births.
It was first described by
H.F.Klinefelter in 1942.

25. Klinefelter Syndrome
The XXY condition comes due to
fusion of abnormal egg(XX) with
normal sperm(Y) or a normal egg(X)
and abnormal sperm(XY).

26. Klinefelter Syndrome
The abnormal sperm and egg are
the outcome of primary
nondisjunction of sex chromosomes
during gametogenesis.

27. Symptoms
Taller
Fatter around the belly
Slower in developing motor skills,
coordination, speed, and muscle
strength

28. Symptoms
Smaller testes and penis
Breast growth (Gynaecomastia)
Less facial and body hair
Low sperm production.

29. Diagnosis and treatment
Diagnosis is possible from genetic
analysis like chromosome maps.
Treatment is not found.