This document discusses genetic mutations. It begins by defining genes and DNA, then describes the different types of genetic mutations including point mutations, frameshift mutations, deletions and repeats. It discusses the causes of mutations including spontaneous errors and environmental factors. The document outlines several diseases caused by mutations and describes diagnostic tests and potential treatments, noting that currently there is no cure for genetic disorders. It concludes by emphasizing the importance of genetic mutations as a cause of disease.

1. Genetic mutation
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DR. JIBRIL IHSAN MUNZALI
REGISTRAR, DEPT OF HISTOPATHOLOGY
NHA
4/7/2013

2. Outline
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 Introduction
A. What are genes?
B. What are mutations?
C. What does genetic mutation mean?
 Types of genetic mutation
 Causes of genetic mutation
 Diseases caused by genetic mutation
 Diagnosis/Treatment
 Conclusion
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3. Genes
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 A gene is a segment of DNA
that encodes a specific
peptide or protein.
 DNA is the genetic material
within the nucleus or
mitochondria where an
individual’s genetic
information is stored.
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4. Nucleotides
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 DNA is composed of sequence
of nucleotides
 Each nucleotide is made up of
three components.
 There are four types of
nucleotide bases.
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5. DNA
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 The nucleotides are covalently bound to each other
through phosphodiester bonds to form a linear
structure.
 Nucleotides are non covalently bound to each
other through hydrogen bonds forming a double
helix.
 DNA polymers combine with proteins termed
histones to form nucleosomes. These fibers form
very compact structures known as chromosomes.
 The order or sequence of the nucleotides in the
DNA chain is the genetic code present within the
cell.
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6. Protein synthesis
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Protein synthesis Genetic code
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7. DNA Replication
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 Replication of genetic
material occurs during the
S phase of the cell cycle
 DNA polymerase needs a
pre-existing DNA to form
two new double bond
strands identical to the
original strand
 Every new double strand is
semi-conservative (half old
and half new)
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8. Genetic mutation
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 Genetic mutation is a
permanent heritable
change in a gene of an
individual.
 It leads to formation of
abnormal proteins or
non-production of
proteins.
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9. Mutations
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 Mutations occurs at a frequency of about 1 in every 1 billion base
pairs.
 Everybody has about 6 mutations in each cell in their body.
 May occur in either introns or exons or even mitochodrial genes.
 Mutations could be germline or somatic
 It could be deleterious or beneficial.
 May follow classic Mendelian patterns or non classic mode of
inheritance.
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10. Causes of genetic mutation
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 Could occur spontaneously or could be acquired
 Spontaneous mutations arise during normal DNA replication as DNA
polymerase may make mistakes during replication.
 If DNA errors are not repaired, mutations arise.
 Other spontaneous types of DNA damage include tautameric
shifts, alkylation, oxidation or hydrolysis
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11. Examples of base damage
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 These types of damages
cause the chemical
structure of the bases to
change.
Hydroxylation
 They may change to
another type of base.
Tautameric shift  They then “mis pair” with
incorrect bases.
 This leads to abnormality
in the reading frame.
Oxidation
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12. Acquired causes
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 Acquired causes include
drugs, radiation, viruses.
 Drugs may cause
alkylation, oxidation etc
 Ionizing radiation causes
breaks and cross linking
 Viruses may cause
degradation of certain
genes.
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13. Types of genetic mutation
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1. Point mutations: This is the substitution of one nucleotide
with another changing the sequence of the codon. This
could lead to a misense, nonsense or even synonymous
mutation.
2. Frame shift mutations: This is when there is insertion or
deletion of a single base or a number of bases not in the
multitude of 3 causing alteration of the reading frame.
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14. Types of mutations
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3. Deletions of a codon/three-base deletion: Leads to deletion of
an amino acid in a protein thus the protein is defective eg cystic
fibrosis
4. Large deletions: Could also occur leading to deletion of the
whole gene leading to absent protein or hybrid protein.
 Trinucleotide repeats
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15. Point mutation: Nonsense mutation
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16. Missense mutation
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 Sickle cell anaemia
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17. Frameshift mutation
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18. Frame shift mutation
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19. Three base deletion
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21. Diagnosis/Treatment
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 Biochemical testing of affected protein.
 PCR can also be used to amplify and identify the affected
gene/genes .
 There are currently no “cures” for genetic disorders,.
 Gene therapy is being looked into: It may be possible to
replace a defective gene with a normal copy.
 Second, the function of an abnormal gene may be abrogated
by administering anti-sense RNA or by RNA-mediated
interference
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22. Conclusion
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 Genetic mutations are important causes of both heritable
and acquired human diseases.
 They usually affect genes with large effects.
 Environmental factors such as chemicals, drugs and
radiations are important causes of radiation.
 Currently, genetic mutations represent a group of
diseases, a large extent to which are still unknown and
treatment of which is still under research.
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23. THANK YOU VERY MUCH.
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