A Man with Syndactyly, an Autosomal-Dominant Condition, Has One Child

question 10

Multiple Choice

A man with syndactyly, an autosomal-dominant condition, has one child who also has syndactyly. His unaffected wife states, "Because the risk for having a child withthis problem is 50% and our first child has the problem, the next child will not be affected." What is the best response to this statement?

• A)"That is not quite true because the risk is 50% with each pregnancy, so with all future children, you would have a 50% risk."
• B)"That is not quite true because you could also have the mutation but not show the problem if there is variable expressivity."
• C)"That is correct, but if you have more than two children, half of them will have syndactyly, and 50% will not have it."
• D)"That is correct, and if you only have two children, the second one will not have syndactyly."

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Definitions:

Convergence

The tendency of unrelated animals and plants to evolve superficially similar characteristics under similar environmental conditions or the movement of eyes inward towards the nose.

Cone Sensitive

Refers to the responsiveness of cone cells in the retina to different wavelengths of light, enabling color vision.

Lens Rigidity

The stiffness of the eye's lens, which increases with age, affecting its ability to change shape and focus on objects at various distances.

Suspensory Ligaments

Fibrous tissues that support an organ or structure, such as the ligaments supporting the lens of the eye, allowing it to change shape for focusing.