Multiple Choice
Which description is an example of a phenotype?
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1. Introduction to Genetics
Fundamentals of Genetics
Multiple Choice
Which of the following disorders is most accurately classified as a single-gene (Mendelian) disease?
A
Cystic fibrosis (mutations in the CFTR gene)
B
Coronary artery disease (typically polygenic and influenced by lifestyle factors)
C
Type 2 diabetes mellitus (typically multifactorial with strong environmental influences)
D
Neural tube defects (typically multifactorial with folate and genetic contributions)
Verified step by step guidance1
Step 1: Understand the definition of a single-gene (Mendelian) disease. These diseases are caused by mutations in a single gene and follow Mendelian inheritance patterns (dominant, recessive, or X-linked).
Step 2: Review each disorder and classify it based on its genetic basis: whether it is caused by mutations in a single gene or influenced by multiple genes and environmental factors.
Step 3: Recognize that cystic fibrosis is caused by mutations in the CFTR gene, which is a classic example of a single-gene recessive disorder.
Step 4: Note that coronary artery disease, type 2 diabetes mellitus, and neural tube defects are complex disorders involving multiple genes and environmental influences, so they are not single-gene diseases.
Step 5: Conclude that cystic fibrosis is the disorder most accurately classified as a single-gene (Mendelian) disease because it fits the criteria of being caused by mutations in one gene with a clear inheritance pattern.
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