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Genetic Diseases
Modern genetics: Genetic diseases.
Genetic Diseases
ALBINISM
THALASSEMIA
SCID [bubble boy syndrome]
AGAMMAGLOBULINEMIA
SICKLE CELL ANAEMIA
HUNTINGTON’S CHOREA
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Sickle-Cell Anaemia, also sickle-cell disease, hereditary
condition in which haemoglobin, is altered, leading to
periodic interruptions in blood circulation.
The RBC in which the altered haemoglobin is contained
also changes its shape, from round to crescent (sickle shaped).
The sickle-shaped red cells interfere with normal blood flow
by plugging up small blood vessels. The amount of oxygen
in the blood also reduced.
The disease is found predominantly in blacks; it also occurs
in the Middle East and the Mediterranean area.
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Sickle-Cell Anaemia
Symptoms:
enlargement of the abdomen and heart,
painful swelling of the hands and feet.
In adolescence, sexual maturation may be delayed.
The affected people exposed to infections and leg ulcers.
The patients dies due to damaged heart, kidney, spleen, brain as a
result of clogged blood vessels or vascular obstruction.
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Sickle-Cell Anaemia
Sickle-cell anaemia occurs when an individual inherits
autosomal mutant allele Hbs from each parent.
The persons with the genotype HbSHbS suffer with Fatal
haemolytic Anaemia
In homozygous condition (HbS HbS) it causes production of
abnormal haemoglobin S.
The normal haemoglobin is HbA (HbAHbA)
Persons with heterozygous genotype HbAHbS are said to be
carrier and they survive.
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
SICKLE CELL ANAEMIA
• Haemoglobin is composed of iron and protein.
• Aminoacids are arranged in four polypaptide
chains.
• They are two identical alpha chains and beta
chains.
• The glutamicacid in the beta chain of haemoglobin is
replaced by valine aminoacid leads to sickle cell anaemia.
• As a result the normal shape of the haemoglobin is
changed in to sickle shape.
A power . presentation
from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
The word “thalassemia” is derived from the
Greek word for “sea”; the disease was
called this because it is more common in
Mediterranean origin. However, the disorder
is found worldwide.
This is an erythroblastic anaemia due to homozygous
recessive gene expression in children.
It is an inherited form of anaemia in which there is reduced
synthesis of one or more of the four globin chains, usually 2α
and 2β which make up haemoglobin in RBCs.
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Thalassemia
the main forms in adults being broadly characterized
as a- or ß-thalassaemias according to whether the
genes for the a or the ß chain are abnormal.
Types of Thalassaemia:
i. Thalassemia Major – Homozygous – severe form
ii. Thalassemia Minor – Heterozygous – milder form
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Thalassem
ia
Clinical manifestations:
Decrease in the bone marrow activity
Splenomegaly (enlarged spleen)
Hepatomegaly (enlarged liver)
Peripheral haemolysis
Normal RBC
Thalassemic RBC
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
People who suffer from an unusual
deficiency of gamma globulin known as
agammaglobulinemia.
Patients are deficient in antibodies and may
require periodic infusions of gamma
globulin to maintain the immune system
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
agammaglobulinemia.
agammaglobulinemia is a recessive gene
disease wherein -globulin synthesis
fails to occur.
Patient shows great deficiency or total
absence of plasma cells and unusual
lymph nodes.
The failure of antibody synthesis leads
to viral and bacterial infections
especially of the chest.
This disease mostly affect boys.
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Albinism
Albinism is an inherited disorder of melanin metabolism leads
to absence of melanin in the skin, hairs and eyes.
Clinical characteristics:
milk white colored skin and marked photophobia.
Genes undergo mutation that do not produce particular
enzymes for metabolic pathways.
In Phenylalanine metabolism, a chain of enzyme mediated
reactions occur.
Change or absence of this enzyme is due to defective gene
results in physiological abnormalities.
A power . presentation
from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
A power . presentation
from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Albinism
In albinism complete lack of melanin pigment causes
albino to suffer- Ratio of the sufferer is 1:5000, 1:25000.
Types of albinism:
1) Total albinism: melanin pigment is completely absent
in whole body
2) Localized albinism: melanin pigment absent in eye
[ocular albinism]
3) Partial albinism: melanin absent in skin hair
Recessive genes ‘aa’ do not produce the Tyrosinase enzyme which
converts DOPA (3,4- Dihydroxy- phenylalanine) into melanin.
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
HUNTINGTON’s CHOREA
Chorea (Greek, choreia, ”dance”), a clinical manifestation of
certain diseases, characterized by involuntary, purposeless,
spasmodic movements in the entire body.
Chorea is most commonly associated with Huntington's
disease (also known as Huntington's chorea)
Huntington’s disease affects the cerebral cortex which of
the brain controls thought, perception, memory, and other
complex functions.
Huntington’s disease also affects other areas of the brain
involved in movement and coordination.
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
HUNTINGTON’s CHOREA
Huntington's chorea is caused by autosomal dominant
gene located on 4th chromosome – occur at the age
between 35 and 40 years.
Symptom: uncontrolled jerking of the body is due to
involuntary twitching of voluntary muscles.
Progressive degeneration of Central nervous system.
Gradual mental and physical deterioration.
Deterioration of intellectual faculty, depression, occasional
hallucination and delusions and other psychological problems.
This is incurable.
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Severe Combined Immuno Deficiency
[bubble boy syndrome]
It is inherited disease affecting children.
gene for this disease called ADA (Adenine Deaminase) is
located in the 20th chromosome.
Symptoms:
 Lack of Immune defense mechanism against infection due
to rapid death of WBC.
 The affected child is kept in a sterile bubble.
 Unless given bone marrow transplant, the life span of the
child is short.
A power . presentation
from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Severe Combined Immuno Deficiency
[bubble boy syndrome]
The most dangerous group of immune deficiencies resulting
from B- and T-lymphocyte malfunction is severe combined
immunodeficiency (SCID).
Within 3 to 12 months after birth, infants with SCID develop
recurrent bacterial, viral, or fungal infections.
About 30 percent of these infants suffer from an enzyme
deficiency known as adenosine deaminase (ADA) deficiency.
In the absence of adenosine deaminase, T- lymphocytes
cannot develop normally.
A power . presentation
from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
A power . presentation
from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
Tissue protein
Adrenaline and Non adrenaline
Dietry protein
Phenyl Alanine
3,4,dihydroxy phenyl alanine
albinism
Tyrosine
melanine
Thyroxine
Phenyl Ketonuria
Phenyl Pyruvate
Goitre & cretinism
Hydroxy phenyl pyruvate
Tyrosinosis
Homo genetisic acid
Alkaptunuria
Maley lacto acetic acid
Fumaryl aceto aceticacid
Fumaric acid and acetoaceticacid
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
PHENYLKETONURIA
• The person with genotype pp fail to produce the phenyl alanine
hydraxylase enzyme.
• This enzyme converts the phenylalanine in to tyrosine.
• Metabolic block occur in this reaction due to lack of phenylalanine
hydraxylase.
• So the phenylalanine concentration accumulates in the blood
plasma, cerebrospinal fluid and urine.
• This syndrome causes mental deficiency , pigmented patches on
the skin, excessive sweating , non pigmented hairs and eyes.
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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Modern genetics: Genetic diseases.
end
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from T.MADHAVAN, M.Sc., M.L.I.S., M.Ed., M. Phil. (FS), PG.D.C.A., Lecturer in Zoology.
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