Short overview of some genetic disorders

1. Genetic Disorders

2. INTRODUCTION
What is genetic diseases/disorders?
The human body is composed up of cells , each one specializing a
particular function like sensing light, smelling etc, So the chromosomes
which are the sub cellular structure that exist in the nucleus of each cell
that makes a human body .There are 23 pairs of chromosomes in
human, these chromosomes are responsible for transferring genetic
information from one generation to another.
Most people have the concept that genetic disease must be the
one which is transmitted from one generation to next. Actually this is
not totally correct. In medicine genetic disease refers to one that is
caused by abnormalities of the genetic material at the stage of germ
cells or early embryo.

3. CATEGORIES OF GENETIC DISORDERS
a) Chromosomal Disorder: Abnormalities in chromosome
structure such as missing or extra copies.
b) Single Gene Disorder: Disorders caused by abnormality or
mutation in the sequence of a single gene. The pure genetic
diseases are caused by a single gene in the human DNA. These
are classified as Dominant, Recessive and X-linked diseases.
c) Multifactorial Disorders: That are caused by the result of the
combined effect of genetic and environmental factors.
d) Mitochondrial Disorders: Caused by mutation in the non
chromosomal DNA of mitochondria.

4. COMMON GENETIC DISORDERS
• Gaucher Disorder
• Huntington’s Disorder
• Hemophilia
• Parkinson’s Disorder
• Sickle Cell Anemia
• Cystic Fibrosis
• Down Syndrome
• Alzheimer’s Disorder
• Thalassemia
• Tay-Sachs Disorder

5. GAUCHER DISORDER
• Gaucher disease is a genetic disorder handed down from
generation to generation
• It is most common of a genetic disorder
• Caused by the deficiency of an enzyme β-glucocerebrocidase
• When there is not enough of the enzyme , the fat can not be
broken down and is stored primarily in the liver and spleen.
• Other body organ, tissues and bones are also effected , in rare
cases it may also accumulates in the brain.
• Its symptoms are;
• Bone pain and fractures, Seizures, Liver and spleen enlargement
and fatigue.

7. HUNGTINGTON’S DISEASE
• It results from genetically programmed degeneration of nerve
cells in certain areas of the brain
• This degeneration causes uncontrolled movements , loss of
intellectual faculties
• Emotional Disturbance
• The Symptoms of this disease are ;
• Mood Swings, irritability , depression, loss of memory and
uncontrolled movements
• As this disease progresses walking and speech become more
difficult, the memory and intellectual functions continue to
decline.

8. HEMOPHILIA
• Hemophilia is the oldest known bleeding disorder.
• It is sex-linked disorder, b/c of which it appears mostly in males.
• Hemophilia is like any other sex-linked disorder, b/c the hemophilia
gene is on the X chromosome.
• 2 types of hemophilia;
• Hemophilia A: Lack of the blood clotting protein factor VIII.
• Hemophilia B: Lack of the blood clotting protein factor IX.
• Symptoms;
• Main symptom is once bleeding starts the child bleeds longer than
normal.
• It may include; Nosebleeds, bleeding for no reason, blood in the urine or
stool and bleeding into a joint, which can cause tightness, swelling and
pain.

10. PARKINSON’S DISEASE
• Parkinson’s disease is a neurological condition that has a
genetic component next to Alzheimer’s.
• The chances of getting developing Parkinson’s gets
higher as age increases.
• Causes of Parkinson; DOPAMINE chemical produced in
the middle part of the brain that is responsible for
organizing coordinated movements and to send this
signal to the control centers of the brain.
• In Parkinson's chemical production less and functioning
starts to shut down slowly and patient begins to lose
control over vital voluntary movement.
• Symptoms; Memory loss, blurriness and lack of postural
stability.

12. SICKLE CELL ANEMIA
• Sickle cell anemia is blood related disorder that affects the
hemoglobin molecule and causes the entire blood cell to
change shape under stressed conditions.
• In sickle cell anemia hemoglobin molecule is defective.
• Round form of blood cells changes into long, rod-like
structures which become stiff and assumes sickle shape
so cell failed to carry oxygen.
• Normal red blood cells live 120 days in the bloodstream,
but sickled red cells die after about 10 to 20 days.
• Symptoms; Lung and heart damage, eye damage,
arthritis and fatigue etc.

14. THALASSEMIA
• It is a blood related genetic disorder which involves the
absence or errors in genes responsible for production of
hemoglobin.
• The severity of disease depend on the mutations involved
in the genes and their interplay.
• Hemoglobin has 2 sub units referred as alpha and beta,
chromosome 16 responsible for alpha sub unit and
chromosome 11 for beta sub unit, lack of particular sub
units determine the type of thalassemia.
• Symptoms; Reduce fertility or even infertility, jaundice,
paleness, poor appetite

16. CYSTIC FIBROSIS
• An inherited disease that affects sodium and chloride channels
in the body and causes respiratory and digestive problems.
• It is monogenic and caused by mutation in a single gene on
chromosome 7.
• Gene contains building information for CFTR (cystic fibrosis
trans-membrane conductance regulator)
• CFTR is a protein that in humans is encoded by the CFTR
gene,and due to mutation it becomes non-functional.
• Usually diagnosed at birth and occurs both in males and
females.
• Symptoms;
• Excessive production of mucus in air tract, poor appetite,
tiredness etc.

19. TAY SACHS DISEASE
• Tay-sachs disease is a fatal genetic disorder in which
harmful quantities of a fatty substance called Ganglioside
GM2 accumulate in the nerve cells in the brain.
• This is caused by a decrease in the functioning of
Hexosaminidase A enzyme.
• Its abnormal activities causes an accumulation of fat in
the nerve cells leading to paralysis, dementia, blindness
and even death.
• This disease/disorder is autosomal recessive which
means that an individual must inherit both the two
defective genes, one from each parent.

21. ALZHEIMER’S
• Alzheimer's is a form of dementia that causes changes in
the brain.
• Also affects a person’s memory, mood and behavior.
• Disease mostly affects people over 65.
• There is no specific test for Alzheimer disease however
physician are able to look at a person medical history and
give a physiological and memory tests to see how efficient
the brain is.
• Symptoms;
Memory loss etc

23. DOWN SYNDROME
• Down syndrome is caused by an extra chromosome
present on chromosome 21.
• Down syndrome is caused by mutations.
• Form of down syndrome;
• Klinefelter’s syndrome also known as the XXY
condition, is a term used to males who have an extra X-
chromosome in most of their cells.
• Turner’s syndrome is a chromosomal condition related
to the X-chromosome that alters development in females.
It leads to infertility, webbed neck, skeletal abnormalities,
heart defects and kidney problems.