Transcript Autosomal Dominance Inheritance

Autosomal Dominance
What’s an Autosome?
• Autosome: Non sex chromosome
– Ex: Autosomal disorders: gene for the disease is found on
chromosomes 1-22
• Autosomal Recessive Inheritance
– Must inherit two copies of the recessive allele to be affected
– Healthy is dominant (HH or Hh)
– Disease is recessive (hh)
– Ex: Cystic fibrosis, PKU, Albinism, Sickle cell anemia
• Autosomal Dominance Inheritance
– Only need to inherit one copy of the dominant allele to be
affected
– Disease is dominant (HH or Hh)
– Healthy is recessive (hh)
– Ex: Familial hypercholesterolemia (also called FH), Huntington’s
disease, Neurofibromatosis
Autosomal Dominance Inheritance
• Disease is dominant (HH or Hh)
– Homozygous dominant: early death and don’t survive to reproduce
– Heterozygous live into adulthood
• Healthy is recessive (hh)
• Familial hypercholesterolemia (FH) causes abnormally high levels of
cholesterol in blood leading to heart disease/stroke by age 30. Complete a
pedigree chart for all 5 people mentioned in the following story: Paul has FH
and Stacy is healthy. The two have 3 children. After testing, the middle child
is the only healthy child.
Hh
Key
disease
disease
hh
Paul
Stacy
H = FH disease
h= healthy
healthy
healthy
Hh
hh
Hh
Video about Huntington's disease
• Autosomal
dominant disorder
• Brain cells start to
die in late 30’s
• Causes
uncontrollable
muscle jerking
• Death usually in
40’s-50’s
• No treatments
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video doesn’t work
Autosomal Dominance Inheritance
• Disease is dominant (HH or Hh)
– Homozygous dominant: early death and don’t survive to reproduce
– Heterozygous live into adulthood
• Healthy is recessive (hh)
• Huntington’s disease is an autosomal dominant disorder found on chromosome 4.
Complete a pedigree chart for all 3 people mentioned in the following story: Betty
and Marcus met at a support clinic they have been attending to help them cope
with the knowledge of their illness with Huntington’s disease. They would like to
know the chance of having a healthy child, now that Betty is pregnant.
Hh
Key
Disease
(severe)
disease
Hh
Marcus
Betty
H = Huntington’s disease
h = healthy
disease
healthy
?
Woody Guthrie:
This Land is Made for You and Me
Review
1) How are autosomal dominant disorders different from autosomal
recessive disorders?
2) What are the possible genotypes of someone with an autosomal
dominant disorder?
3) In all likelihood, what is the genotype of an adult with an autosomal
dominant disorder?
4) Complete a pedigree from the following story:
Jerome is concerned about Huntington’s disease (HD) since his
father recently passed away due from the disorder. After a gene test,
he is found to not have the HD gene. He marries Raquel and they are
now preparing for their first child.
a) What is the likelihood of the child having HD if Raquel is healthy?
b) What is the likelihood of the child having HD if Raquel has HD?