Download Human Genetic Mutations

5/15/2016
Causes of Genetic Disorders
• Genetic disorder – abnormal condition that a person
inherits through genes or chromosomes.
Human Genetic
Mutations
What is a mutation?
• A mutation is a permanent alteration in a sequence of DNA
that makes up a gene.
• Types of Gene Mutations:
–Deletion
–Inversion
–Translocation
–Insertion
–Duplication
–Substitution
• Some are caused by mutations in the DNA of genes. (Gene
Mutations)
• Others are caused by changes in the overall structure or
number of chromosomes. (Chromosomal Mutations)
Gene Mutations
• Small scale: one gene is affected.
• Large Scale: multiple genes are affected.
• Any change to the DNA sequence of a gene:
-Nucleotides/Bases may be added, missing,
or changed
Gene Deletion
Cystic Fibrosis & Cri du Chat
• Body produces abnormally thick
mucus in the lungs and intestines
making it hard to breathe.
• Infants often have a high-pitched cry
that sounds like that of a cat. Results
intellectual disability and delayed
development.
Changes the number of DNA bases by removing one or more genes
(pieces of DNA).
One or more genes are removed
Causes:
Wolf-Hirschhorn syndrome, Cri du Chat syndrome, Cystic Fibrosis
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Gene Inversion
Cleft Palate and Club Foot
• Cleft Palate affects the top of
the mouth – a gap/opening
exists.
• Club Foot is where the foot is
twisted out of shape or position.
An entire section of DNA is reversed or flipped end-to-end on a
a segment of genes flip end-to-end on the chromosome
chromosome.
Causes:
cleft palate, club feet
Gene Translocation
Gene Insertion
Increases the number of DNA bases in a
gene by adding a piece of DNA.
AMaterial
whole chromosome
or chromosome
segment
is swapped with
another chromosome
attaches to another chromosome or segment
creating a hybrid.
Causes:
Causes:
Burkitt’s Lymphoma
Huntington’s Disease and Fragile X
Syndrome
(cancer of the lymph nodes, in children)
Huntington’s Disease & Fragile X
• Huntington’s Disease causes
nerve cells in the brain break
down over time.
Gene Duplication
• Fragile X syndrome causes a range
of developmental problems
including learning disabilities and
cognitive impairment.
A segment
genes
twice and added to
A piece
of DNA isofcopied
oneisorcopied
more times.
the chromosome
Causes:
Charcot–Marie–Tooth disease
(high arched foot, claw feet, confined to a wheelchair)
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Gene Substitution
Charcot–Marie–Tooth disease
• Charcot-Marie-Tooth disease is characterized by loss of muscle tissue
and touch sensation, predominantly in the feet and legs but also in the
hands and arms in the advanced stages of disease.
A piece of DNA exchanges one base for another.
(add this to the bottom of your page)
Causes:
Sickle Cell Anemia
Sickle- Cell Disease
•
The Hemoglobin shape in blood changes,
causing blood cells to have a sickle shape.
•
The sickle shape can clog blood vessels and
cannot carry as much O2 as normal shaped red
blood cells.
•
A person must have 2 alleles for this gene to
have this disease.
Chromosomal Mutations
• Any change in the structure or number of
chromosomes
• A chromosome mutation causes individuals to
have an abnormal number of chromosomes.
What are chromosomes?
• Humans have 23 pairs of
chromosomes, with one
chromosome from each
parent.
• The chromosomes are coiled
up DNA.
• Under normal conditions all
of the chromosomes are
inherited in tact.
Down Syndrome
• Cause:
Nondisjunction of
chromosome 21
• Three copies of chromosome 21 =
“TRISOMY 21”
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Warkany Syndrome
Edward Syndrome
• Cause: An additional copy of chromosome 18 in
some or all of the cells in the body.
• Three copies of chromosome 18 =
“TRISOMY 18”
Patau Syndrome
• Cause: An extra 13th chromosome.
• Three copies of chromosome 13 =
“TRISOMY 13”
• Can cuase severe intellectual disability
and physical defects.
• Also known as cleft lip
Klinefleter Syndrome
• Cause: An extra copy of
chromosome 8.
• Three copies of chromosome 8 =
“TRISOMY 8”
• Characteristics:
• Uneven legs
• Curved bones
• Creases in feet
and hands
Turner Syndrome
• Cause: A complete or partial absence of
the second sex chromosome.
– XO instead of XX
• A chromosomal disorder that affects only
females.
• Tend to be smaller in size and have some
exaggerated features.
Genetic Screening - Amniocentesis
• Cause: A genetic condition in which a boy is born with an
extra copy of the X chromosome.
– XXY instead of XY
• Tend to have more
feminine like
characteristics.
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