Hip Dysplasia Pedigree
Name: _____________________________ Per: ___________
Charlie is a male, third generation, pure breed German Sheppard. He has a serious problem with his hips
called hip dysplasia. This arthritic problem causes pain and discomfort as Charlie gets older. Hip dysplasia is a
genetic disorder that spread within the pure breed German Shepard population due to inbreeding. Breeders want
to maintain the pure bloodline within the German Shepard population because pure breed dogs are worth more
money.
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Charlie has 4 siblings, two brothers, and two sisters. He is the only one with hip dysplasia.
Charlie’s sister married a dog without hip dysplasia but they had a male dog with hip dysplasia.
Charlie’s mother did not have hip dysplasia and neither did his father.
Charlie’s mother had 5 siblings, three brothers, and two sisters all with hip dysplasia.
Charlie’s maternal grandmother had hip dysplasia but his maternal grandfather did not.
Little is known about Charlie’s father’s siblings but neither of his parents had hip dysplasia.
Key
1. Make a key.
2. Draw a pedigree for the family.
3. Label the four generations with Roman Numerals.
I.
II.
III.
IV.
Is this a dominant autosomal trait or a recessive autosomal trait? _______________________________________
hint: If two parents without the disorder have a child with it, it’s recessive. If two parents with the disorder have a child without it, it’s dominant.
What is Charlie’s genotype with regards to hip dysplasia? ____________________________________________
Charlie is mated to a girl dog without hip dysplasia.
What kind of gametes will the female produce?
What kind of gametes will Charlie produce?
sperm
sperm
or
or
egg
egg
Complete the chart below. What kinds of gametes can they produce?
Female
gamete #1
gamete #2
Male (Charlie)
gamete #1
gamete #2
What process produces gametes? ________________________________________________________________
Dogs have 74 chromosomes. How many will be in each gamete? ________________
When the maternal and fraternal gametes combine this process is called? ________________________________
How many chromosomes will be in a dog zygote? __________________
What happens if this process goes wrong and the resulting gamete has extra or missing chromosomes? What is
this type of mistake called? __________________________________________________________________
Parents _______ X _______
They have some puppies with hip dysplasia
Genotypes _____________________________________
Ratio _________________________________________
Phenotypes ____________________________________
Ratio _________________________________________
What would be the chance that their pups would contract the disease? _________________________________
How can you tell if Charlie’s mate is homozygous or heterozygous for no hip dysplasia? Explain your reasoning?
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Hip dysplasia is actually polygenic. Its inheritance patterns don’t follow the classic dominant/recessive patterns
you see in this activity. Explain what polygenic traits are?
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