& Genetic Disorders
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Show the genetic history
of a family
“Genetic Family Tree“
Shows phenotypes one
generation to the next
Sometimes shows
genotypes from one
generation to the next;
and sometimes you can figure out the genotype
based on your knowledge of inheritance
The Weasley Family Tree
http://nd05.jxs.cz/776/087/f51a5cac71_86805403_o2.png
FF= Free hanging ears
Ff= Free hanging ears
ff= Attached ears
Ff
ff
Ff
FF
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Ff
Ff
FF
FF
FF
Ff
Ff
ff
Ff
each generation is represented using a Roman Numeral
circles are females, squares are males
a line connecting two shapes indicated a mating
shaded in areas indicate an individual affected by the trait
What do you see?
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Pedigrees tell the phenotypic/genotypic story:
◦ Who bred with who? (i.e. Any new traits
introduced?)
◦ What was the relationship between relatives?
(i.e. Third cousins once removed)
◦ What traits were passed on? (i.e. Hanging ears or
Sickle Cell Anemia)
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So who would cares?
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A genetic disorder is a disease that is caused
by an abnormality in an individual's DNA.
Abnormalities can range from a small
mutation in a single gene to the addition or
subtraction of an entire chromosome or set
of chromosomes.
(The University of Utah, 2013)
Common Misconception Alert!
Genetic disorders are all
inherited.
– NOT TRUE!
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Level 1: Single Gene Disorders
◦ Mutation of a single gene cause protein to be
altered or deleted
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Level 2: Chromosome Abnormalities
◦ Entire chromosomes or large segments are deleted,
duplicated or altered
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Level 3: Multifactorial Disorders
◦ Mutations in multiple genes, often coupled with
environmental factors
(The University of Utah, 2013)
(The University of Utah, 2013)
Environmental
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Stress
Diet
Physical/Mental Abuse
Drugs and Alcohol
Exposure to Radiation,
Pathogens, Toxins and
Chemicals
E.g. A person exposed to
head injuries may be more
likely to develop
Alzheimer’s.
Heredity
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Family Medical History
◦ 1st, 2nd and 3rd generation
◦ Skipped Generations
◦ Carriers
Autosomal Dominant/ Recessive
X-Linked Dominant/ Recessive
Mitochondrial (paternal mtDNA)
E.g. Huntington’s Disease is an
Autosomal Dominant disease,
and thus every generations will
be affected by it.
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Down’s Syndrome: Trisomy 21
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Klinefelter Syndrome: XXY
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Turner Syndrome: XO
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Fragile-X Syndrome: X-Linked Dominant ( FMR1)
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Duchenne Muscular Dystrophy: X-Linked Recessive (DMD gene)
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Huntington’s Disease: Autosomal Dominant (HTT gene)
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Tay Sachs: Autosomal Recessive (HEXA gene)
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Cystic Fibrosis: Autosomal Recessive (CFTR)
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Sickle Cell: Autosomal Recessive (HBB gene)
Royal Family Pedigree
(X-linked recessive)
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Autosomal Recessive
Blood Disorder
Some Symptoms: anemia, fever, chest pain,
increased risk of infections, especially
respiratory infections, death
http://www.youtube.com/watch?v=9AHFHleY
wdU
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Malaria:
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Sickle Cell
◦ Vector-borne disease, parasites are transmitted by
mosquitoes through blood
◦ Symptoms include fever, chills, flu-like illness, may
cause death
◦ In 2010 an estimated 216 million cases of malaria
occurred worldwide and 655,000 people died, most
(91%) in the African Region (CDC, 2010)
◦ Carriers have increased resistance against malaria
◦ 60% protection against overall mortality
◦ http://www.youtube.com/watch?v=1fN7rOwDyMQ&play
next=1&list=PLD371690519F378F5&feature=results_m
ain
= Unaffected Individuals
= Carriers of the disease
= Affected by the Disease