Genetic
disorders can occur either due to change in chromosome number or structure or
mutations. Some of these genetic disorders are listed below.
Name of the disorder
|
Cause
|
Symptoms
|
I
On the basis change in chromosome structure
|
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1.Cri-du-chat syndrome
|
Deletion of whole or part of the short
arm of chromosome 5
|
Infant’s cry like the mewing of a cat,
moon like face.
|
II.
On the basis change in chromosome number
|
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1.Down’s syndrome (Mongolism)
|
Trisomy of chromosome 21
|
Mentally and physically retarded,
round face with broad skull
|
2.Edward’s syndrome
|
Trisomy of chromosome 18
|
Mental retardation with several
congenital malformations
|
3.Klinefilter’s Syndrome
|
Additional X-chromosome (XO)
|
Phenotypically females with
rudimentary sex organs and mammary glands
|
4.Turner’s syndrome
|
Lake of X-chromosome 13
|
Cleft lip, deafness, mental
retardation
|
5.Patau Syndrome
|
Trisomy of chromosome 13
|
Cleft lip, deafness, mental
retardation
|
III.
Gene mutation
|
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1.Albinism
|
Recessive gene which blocks conversion
of amino acid tyrosine to melanin
|
Lack of pigment in the skin, hair and
iris of the eyes
|
2.Cystic fibrosis
|
Recessive autosomal gene in homozygous
condition
|
Increased susceptibility of lung
infection, abnormal pancreatic function
|
3.Fabry’s disease
|
Recessive X-linked (sex-linked) gene
which blocks metabolism of glycophingolipids
|
Lipids as crystals deposit on the
walls of blood vessels of heart, kidneys, eyes, causing shooting pain
|
4. Hemophilia
|
Sex-linked recessive gene causing
defective synthesis of clotting factor
|
Haemorrhage
|
5.Huntington’s disease
|
Dominant autosomal gene
|
Develops at the late age of 30-40
years and slowly leads to loss of control on the movement of limbs
|
6.Muscular dystrophy (Duchenne type)
|
Sex-linked recessive gene during
childhood recessive gene causing
defective synthesis of clotting factor
|
Haemorrhage
|
7.Phenylketonuria (PKU)
|
Recessive autosomal gene in homozygous
condition
|
Brain damage leading to mental retardation
|
8.Sickle cell anaemia
|
Recessive autosomal gene in homozygous
condition resulting in abnormal haemoglobin
|
Inability to carry oxygen by blood
|
9. Tay-sachs disease
|
Recessive autosomal gene after 8-9
months
|
Degeneration of cerebral function
leading to epilepsy, paralysis or even blindness
|
10. Thalassemia (Cooley’s anaemia)
|
Recessive gene in homozygous condition
|
Severe anaemia
|
11. Leasch-Nyhan syndrome
|
Sex-linked (x-linked)recessive trait
|
Development of involuntary movements,
mental retardation
|
12Marfan’s Syndrome
|
Autosomal dominant
|
Abnormalities of the eyes,
cardiovascular and skeletal system
|
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