It is about the genetic disorder, its type and examples of genetic disorder like sickle cell anemia, Alzheimer disease and Down's Syndrome

1. DAV SUSHIL KEDIA VISHWA BHARATI HIGHER
SECONDARY SCHOOL

2. GENETIC DISORDER

3. Contents
• INTRODUCTION
• HISTORY OF GENETICS
• TYPES
• EXAMPLES
• CONCLUSIONS

4. Introduction
A genetic disorder is a disease caused in
whole or in part by a change in the DNA
sequence away from the normal sequence.
Genetic disorders can be caused by a
mutation in one gene (monogenic disorder),
by mutations in multiple genes
(multifactorial inheritance disorder), by a
combination of gene mutations and
environmental factors, or by damage to
chromosomes (changes in the number or
structure of entire chromosomes, the
structures that carry genes).

5. • As we unlock the secrets of the human
genome (the complete set of human
genes), we are learning that nearly all
diseases have a genetic component. Some
diseases are caused by mutations that are
inherited from the parents and are
present in an individual at birth, like sickle
cell disease. Other diseases are caused by
acquired mutations in a gene or group of
genes that occur during a person's life.
Such mutations are not inherited from a
parent, but occur either randomly or due
to some environmental exposure (such as
cigarette smoke). These include many
cancers, as well as some forms of
neurofibromatosis.

6. Father of Genetics
GREGOR MENDEL

7. • 1866; first there was Gregor Mendel who
studied inherited characteristics.
• This was followed by Francis crick and
James Watson who unraveled the DNA
molecule.
• This has led us to understanding the
human genome sequence.
• 1950; Maurice Wilkins, Rosalind Franklin,
francis H.C. Crick of Britain and James D.
Watson of the U.S. discovered chemical
structure of DNA, starting a new branch of
science molecular biology.
History

8. • 1957- Arthur Kornberg of the U.S.
produced DNA in test tube.
• 1966- Genetic code was
discovered.
• 1983- Barbara McClintock
discovered that genes are able to
change position on
chromosomes.
• Late 1980’s- An international
team of scientist began the
project to map the human
genome.
• 1990- Gene therapy was first
used for patient.

9. Chromosomal Genetic Disorder
• A chromosomal disorder is a missing, extra, or irregular
portion of chromosomal DNA.
• Most chromosome abnormalities originate in the egg
or sperm (gametes) but some happen during embryo
?development or are inherited? from a parent.
• While some chromosome abnormalities are harmless,
some are associated with clinical disorders.
• Larger abnormalities may be visible with a microscope
in a test called chromosome analysis or karyotyping.
• Smaller chromosome abnormalities can be identified
using a specialized genetic test that scans a person's
chromosomes for extra or missing parts.
• These tests include chromosomal microarray analysis
and fluorescent in situ hybridization (FISH).
• Chromosomal disorders can be from an atypical
number of chromosome or a structural abnormality in
one or more chromosome. So there are two types of it.

10. Numerical Abnormalities
• They occur when a person has one or more extra copies
of a chromosome (one extra is trisomy, and two extra is
tetrasomy) or is missing a chromosome (monosomy).
• Trisomy can affect any of the 23 paired chromosomes,
but the most common are trisomy 21 (Down
syndrome), trisomy 13, and trisomy 18. These
abnormalities are visible with a microscope in
karyotyping.
• The most severe chromosome disorders are caused by
the loss or gain of whole chromosomes, which can
affect hundreds, or even thousands, of genes? and are
usually fatal.
• A few numerical abnormalities support development to
term, either because the chromosome is small and/or
contains relatively few genes or because there is a
natural mechanism present to help adjust gene dosage.

11. Structural Abnormalities
• They occur when part of a
chromosome is abnormal. Sometimes
part or all of a chromosome incorrectly
joins with another chromosome,
sometimes parts of chromosomes are
missing or have been duplicated.
• Structural abnormalities can take
several forms.

17. Single Gene Disorder
• Single-gene disorder is a disease caused by a
known alteration or mutation in one of more than
20.000 genes in nearly every cell in the body.
• It may be inherited from both members of a
couple carry the same condition. It can also be
inherited through one or more generations in the
family.
• Individually, single gene disorders are each very
rare, but as a whole, they affect about one per
cent of the population.
• Since only a single gene is involved, these disorders
can be easily tracked through families and the risk
of them occurring in later generations can be
predicted.
• Single gene disorders can be divided into different
categories: dominant?, recessive? and X-linked.

18. Fig: Pedigree diagram showing the
inheritance pattern of dominant
disease.

19. Fig: Pedigree diagram showing the
inheritance pattern of recessive
disease.

20. Fig: Pedigree diagram showing the
inheritance pattern of X-linked
disorder.

21. Multifactorial Genetic Disorder
• Multifactorial genetic disorder refers to the pattern
of inheritance of certain conditions due to a
combination of both genetic and other factors.
• They are also referred to as complex disorders
• Although complex disorders often cluster in
families, they do not have a clear- cut pattern of
inheritance. This makes it difficult to determine a
person’s risk of inheriting or passing on these
disorders.
• Complex disorders are also difficult to study and
treat because the specific factors that cause most
of these disorders have not yet been identified.
• A great number of diseases, such as diabetes,
congenital heart defects, spina bifida, and cancer,
are examples of multifactorial genetic disorders.

22. Down’s Syndrome
• It is the of the most common chromosomal
abnormalities in humans
• During both mitosis and meiosis, there is a
phase where each chromosome pair in a cell
is separated, so that each new cell can get a
copy of every chromosome .
• sometimes during this process, a pair of
chromosomes doesn’t separate evenly,
which results in one of the new cells having
an extra section of chromosome. This is
called nondisjunction.
• With Down syndrome, various types of
uneven chromosome separation result in a
person having an extra copy (or partial copy)
of chromosome 21.
• There are three main types of Down
syndrome: trisomy 21, mosaicism,
and translocation.

26. WHAT IS SICKLE CELL ANEMIA?
• It is genetic disorder that affects RBC
causing them to become sickle or
crescent shaped.
• It is an inherited form of anemia- a
condition in which there aren’t enough
healthy red blood cells to carry
adequate oxygen throughout the body.
• These irregularly shaped cells can get
stuck in small blood vessels which cam
slow or block blood flow and oxygen.

29. Symptoms Complications Treatment
• Anemia
• Painful swelling
of hands and
feet
• Frequent
infections
• Delayed growth
• Vision problem
• Blindness
• Acute chest
syndrome
• Pulmonary
hypertension
• Organ damage
• Gall stones
• Treatment
might include
medications
• Blood
transfusion
• Bone marrow
transplant
• Vaccinations

30. Alzheimer’s Disease
• Alzheimer's disease is a neurological
disorder in which the death of brain cells
causes memory loss and cognitive decline.
• This is an irreversible, progressive brain
disorder that slowly destroys memory and
thinking skills and, eventually, the ability to
carry out the simplest tasks.
• It is caused by a combination of genetic,
lifestyle and environmental factors that
affect the brain over time.
• Impaired speaking, reasoning, memory
loss, difficulty determining time or place
etc are the major symptoms of Alzheimer's
disease.
• This is one of the examples of
multifactorial genetic disorder

32. Symptoms Precautions
- Memory loss
- Mood and personality
changes
- Misplacing items often
- Vision loss
- Difficulty in making
decisions
- Difficulty in completing
familiar works
- social
engagement
- healthy diet that
contains omega-3
fatty acids.
- enough sleep
- stress
management
- regular exercise
- avoid smoking
and drinking
- social engagement
- healthy diet that contains
omega-3 fatty acids.
- enough sleep
- stress management
- regular exercise
- avoid smoking and
drinking