Human ABO blood type is determined by three alleles, two of which (I^A and I^B) produce gene products that modify the H antigen produced by protein activity of an independently assorting H gene. A rare abnormality known as the 'Bombay phenotype' is the result of epistatic interaction between the gene for the ABO blood group and the H gene. Individuals with the Bombay phenotype appear to have blood type O based on the inability of both anti-A antibody and anti-B antibody to detect an antigen. The apparent blood type O in Bombay phenotype is due to the absence of H antigen as a result of homozygous recessive mutations of the H gene. Individuals with the Bombay phenotype have the hh genotype. Use the information above to make predictions about the outcome of the cross shown below.
IᴬIᴮHh×IᴬIᴮHh
3. Extensions to Mendelian Inheritance
Epistasis and Complementation
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
When performing a complementation test, how do you know if two mutations complement?
A
The offspring will have a wild-type phenotype
B
The offspring will have the mutant phenotype
C
The offspring will have an intermediate phenotype between wild-type and mutant
D
The offspring will not look like either wild-type or mutant
Verified step by step guidance1
Understand the purpose of a complementation test: It is used to determine if two mutations that produce a similar phenotype are in the same gene or in different genes.
Set up the test by crossing two organisms, each homozygous for one of the mutations. This will produce offspring that are heterozygous for both mutations.
Analyze the phenotype of the offspring: If the offspring display a wild-type phenotype, it indicates that the mutations complement each other, meaning they are in different genes.
If the offspring exhibit a mutant phenotype, it suggests that the mutations do not complement each other, indicating they are in the same gene.
Consider other possible outcomes: If the offspring show an intermediate phenotype or a phenotype that is neither wild-type nor mutant, further investigation may be needed to understand the genetic interaction.
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