This document provides an overview of genetic diseases and inheritance patterns. It discusses several types of genetic disorders including single gene inheritance, multifactorial inheritance, chromosomal abnormalities, and mitochondrial inheritance. Specific genetic diseases are described for each category, such as cystic fibrosis, sickle cell anemia, and Alzheimer's disease. The roles of genes, chromosomes, and mitochondria in the development and transmission of genetic traits and diseases are also summarized.

1. BIOCHEMICAL
GENETICS
PREPARED BY; MISS RABIA KHAN BABER

2. AIMS AND OBJECTIVES OF PPT
GENETIC
DISEASES
SINGLE GENE
INHERITANCE
MITOCHONDR
IAL
INHERITANCE
CHROMOSOM
E
ABNORMALIT
IES
MULTIFACTO
RIAL
INHERITANCE

3. GENETIC DISEASE

4. GENETIC DISEASE
A genetic disease is any disease caused by an
abnormality in the genetic makeup of an individual.
The genetic abnormality can range from minuscule to
major - from a discrete mutation in a single base in
the DNA of a single gene to a gross chromosomal
abnormality involving the addition or subtraction of
an entire chromosome or set of chromosomes. Some
people inherit genetic disorders from the parents,
while acquired changes or mutations in a preexisting
gene or group of genes cause other genetic diseases.
Genetic mutations can occur either randomly or due
to some environmental exposure.

5. WHAT IS THE HUMAN
GENOME?
The human genome is the entire "treasury of human
inheritance." The sequence of the human genome
obtained by the Human Genome Project, completed in
April 2003, provides the first holistic view of our genetic
heritage. The 46 human chromosomes between them has
almost 3 billion base pairs of DNA that contains about
20,500 protein-coding genes. The coding regions make
up less than 5% of the genome , the function of all the
remaining DNA is not clear and some chromosomes
have a higher density of genes than others. Most genetic
diseases are the direct result of a mutation in one gene.

6. TYPES OF GENETIC
DISORDERS
There are a number of different types of genetic
disorders (inherited) and include:
 Single gene inheritance
 Multifactorial inheritance
 Chromosome abnormalities
 Mitochondrial inheritance

7. SINGLE GENE INHERITANCE
 Single-gene disorders have different patterns of
genetic inheritance, including
 autosomal dominant inheritance, in which only one
copy of a defective gene (from either parent) is
necessary to cause the condition;
 autosomal recessive inheritance, in which two copies
of a defective gene (one from each parent) are
necessary to cause the condition; and
 X-linked inheritance, in which the defective gene is
present on the female, or X-chromosome. X-linked
inheritance may be dominant or recessive.

8. 7 SINGLE GENE INHERITANCE
DISORDERS
1. Cystic fibrosis,
2. Alpha- and beta-thalassemias,
3. Sickle cell anemia (sickle cell disease),
4. Marfan syndrome,
5. Fragile x syndrome,
6. Huntington's disease, and
7. Hemochromatosis.

9. MARFAN SYNDROME
 Marfan syndrome is a disease of
connective tissues that are inherited.
 The severity of Marfan syndrome
varies from one individual to another
and it typically progresses over time.
 A tall, slender build is characteristic
of Marfan syndrome.
 Marfan syndrome affects the
skeleton, eyes, heart and blood
vessels, nervous system, skin, and
respiratory system.
 Marfan syndrome can cause
dislocation of the lens of the eye and
detachment of the retina, resulting
in vision loss in patients with the
condition.

10. HEMOCHROMATOSIS
Hereditary hemochromatosis is
an inherited (genetic) disorder in which
there is excessive accumulation of iron
in the body (iron overload). It is a
common genetic disorder among
Caucasians in the United States,
affecting approximately 1 million
people in the United States. Individuals
affected with hereditary
hemochromatosis may have no
symptoms or signs or they can have
severe symptoms and signs of iron
overload that include sexual
dysfunction, heart failure, joint
pains, cirrhosis of
the liver, diabetes, fatigue, and
darkening of the skin.

11. SICKLE CELLANEMIA
 Sickle cell anemia (SCD) is
an inherited disorder of
the hemoglobin in blood.
 Sickle cell anemia requires the
inheritance of two sickle cell
genes.
 Sickle cell trait, which is the
inheritance of one sickle gene,
almost never causes problems.
 Virtually all of the major
symptoms of sickle cell
anemia are the direct result of
the abnormally shaped
sickled red blood
cells blocking the flow of
blood.

12. MULTIFACTORIAL
INHERITANCE
Multifactorial inheritance is also called complex or
polygenic inheritance. Multifactorial inheritance
disorders are caused by a combination of
environmental factors and mutations in multiple
genes. For example, different genes that
influence breast cancer susceptibility have been found
on chromosomes 6, 11, 13, 14, 15, 17, and 22. Some
common chronic diseases are multifactorial disorders.

13. 7 MULTIFACTORIAL GENETIC
INHERITANCE DISORDERS
1. Heart disease,
2. High blood pressure,
3. Alzheimer's disease,
4. Arthritis,
5. Diabetes,
6. Cancer
7. Obesity.
 Multifactorial inheritance also is associated with
heritable traits such as fingerprint patterns, height,
eye color, and skin color.

14. ALZHEIMER'S DISEASE
 Alzheimer's disease (AD) is a slowly progressive disease of
the brain that is characterized by impairment of memory
and eventually by disturbances in reasoning, planning,
language, and perception. Many scientists believe that
Alzheimer's disease results from an increase in the
production or accumulation of a specific protein in the brain
that leads to nerve cell death.
 The likelihood of having Alzheimer's disease increases
substantially after the age of 70 and may affect 38% of
persons over the age of 85. Nonetheless, Alzheimer's
disease is not a normal part of aging and is not something
that inevitably happens in later life. For example, many
people live to over 100 years of age and never develop
Alzheimer's disease.

15. CHROMOSOMAL
ABNORMALITIES
Chromosomes, distinct structures made up of DNA
and protein, are located in the nucleus of each cell.
Because chromosomes are the carriers of the genetic
material, abnormalities in chromosome number or
structure can result in disease. Chromosomal
abnormalities typically occur due to a problem with
cell division.

16. 4 CHROMOSOMAL
ABNORMALITIES
1. Down syndrome or trisomy 21 is a common genetic
disorder that occurs when a person has three copies of
chromosome 21. There are many other chromosomal
abnormalities including:
2. Turner syndrome
3. Klinefelter syndrome
4. Cri du chat syndrome, or the "cry of the cat" syndrome
 Diseases may also occur because of chromosomal
translocation in which portions of two chromosomes are
exchanged.

17. DOWN SYNDROME
Down syndrome is a genetic
disorder and the most common
autosomal chromosome
abnormality in humans, where
extra genetic material from
chromosome 21 is transferred to a
newly formed embryo. These
extra genes and DNA cause
changes in the development of
the embryo and fetus resulting in
physical and mental
abnormalities. Each patient is
unique and there can be great
variability in the severity of
symptoms.

18. TURNER SYNDROME
Turner syndrome is a chromosomal condition that alters
development in females. Women with this condition
tend to be shorter than average and are usually unable
to conceive a child (infertile) because of an absence of
ovarian function. Other features of this condition that
can vary among women who have Turner syndrome
include extra skin on the neck , lymphedema of the
hands and feet, skeletal abnormalities, heart defects and
kidney problems.

19. SYMPTOMS OF TURNER
SYNDROME
Short stature and non-functioning ovaries which
causes infertility
Some women may also have extra skin on the neck
(webbed neck)
Puffiness or swelling (lymphedema) of the hands
and feet
 Skeletal abnormalities
Heart defects
 High blood pressure,
Kidney problems.

20. KLINEFELTER SYNDROME
Klinefelter syndrome, also known as the XXY
condition, is a term used to describe males who have
an extra X chromosome in most of their cells. Instead
of having the usual XY chromosome pattern that most
males have, these men have an XXY pattern.
Klinefelter syndrome is named after Dr. Henry
Klinefelter, who first described a group of symptoms
found in some men with the extra X chromosome.
Even though all men with Klinefelter syndrome have
the extra X chromosome, not every XXY male has all
of those symptoms.

21. MITOCHONDRIAL
INHERITANCE
This type of genetic disorder is caused by
mutations in the non-nuclear DNA of
mitochondria. Mitochondria are small round or
rod-like organelles that are involved in
cellular respiration and found in the cytoplasm of
plant and animal cells. Each mitochondrion may
contain 5 to 10 circular pieces of DNA. Since egg
cells, but not sperm cells, keep their mitochondria
during fertilization, mitochondrial DNA is always
inherited from the female parent.

22. 3 MITOCHONDRIAL GENETIC
INHERITANCE DISORDERS
1. Leber's hereditary optic atrophy (LHON), an eye
disease
2. myoclonic epilepsy with ragged red fibers (MERRF)
3. mitochondrial encephalopathy, lactic acidosis,
and stroke-like episodes , a rare form of dementia.

23. EPILEPSY
 Epilepsy is a brain disorder in which clusters of nerve
cells, or neurons, in the brain sometimes signal
abnormally causing strange sensations, emotions, and
behavior, or sometimes convulsions, muscle spasms,
and loss of consciousness.
 Epilepsy is not contagious and is not caused
by mental illness or mental retardation. Sometimes
severe seizure can cause brain damage, but
most seizures do not seem to have a detrimental effect
on the brain.
 Epilepsy has many possible causes, from illness to
brain damage to abnormal brain development.
Genetics may also play a role.

24. ENCEPHALOPATHY
Encephalopathy is a term that means brain
disease, damage, or malfunction. Encephalopathy
can present a very broad spectrum of symptoms
that range from mild, such as some memory
loss or subtle personality changes, to severe, such
as dementia, seizures, coma, or death. In general,
encephalopathy is manifested by an altered
mental state that is sometimes accompanied by
physical manifestations ,for example, poor
coordination of limb movements.

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