Transcript Autosomal Dominance Inheritance

Autosomal Dominance Inheritance
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 disorder 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 disorder 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)
• ex: Paul has familial hypercholesterolemia and Stacy is healthy. The
two have 3 children. After testing, the middle child is the only healthy
child.
Hh
hh
Paul
Stacy
Key
disease
disease
H = FH disease
h= healthy
healthy
healthy
Hh
hh
Hh
Autosomal Dominance Inheritance
• Huntington’s disease is a dominant disorder found on chromosome 4.
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 risk of having a
healthy child, now that Betty is pregnant.
Hh
Hh
Marcus
Betty
Key
Disease
(severe)
disease
H = Huntington’s disease
h = healthy
disease
healthy
?
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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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?