This document contains instructions for analyzing three different pedigrees - one for Achondroplasia (a form of dwarfism), one for Phenylketonuria (PKU), and one sex-linked pedigree for colorblindness. For each pedigree, the student is asked to list the genotypes of the individuals based on provided alleles. They are also given four questions about which members show or carry traits and probabilities for offspring in the colorblind pedigree.

1. Name _____________________________ Date ________________ Per _____
Pedigree Analysis
1. Use A to represent the allele for Achondroplasia (a form of dwarfism). Use aa
to represent a normal phenotype who exhibits the recessive trait. Use A_ where
the genotype is uncertain. List the genotypes below.
Individual Genotype
1
2
1
2
3
4
1
2
3
2. Use a P to represent an allele for the normal enzyme that breaks down
phenylalnine and pp to represent the genotype for Phenylketonuria (PKU).
Where you cannot be sure whether an individual with the dominant trait is
heterozygous or homozygous, show the genotype as P_. List the genotypes
below.
Individual Genotype
1
2
1
2
3
4
1
2
3

2. Sex –Linked Pedigree
I
II
III
IV
The above pedigree is a family that carries the colorblindness trait. Use XC for the normal
vision allele. Use Xc for the colorblind allele. Don’t forget, there are no alleles that code
for colorblindness on the Y chromosome in males. List the genotypes below.
Individual Genotype
Questions
1
2 1. Which members of the dominant pedigree show the
1 trait?
2
3
4 2. Which members of the recessive pedigree are
5 considered carriers?
6
1
2 3. Which individuals passed on the color blind trait to
3 their children?
4
5
6 4. If individual 4 in generation IV had a child with a
1 colorblind man, what would the probability of that
child being colorblind?
2
3
4