Question

If in one study with both monozygotic and dizygotic twins, the concordance value for a neurological disorder was 100% for monozygotic twins. Which of the following statements is correct?

a. The concordance value for dizygotic twins will be also 100%.
b. There will be no phenotypic variation in susceptibility for the disorder for all the pairs of twins in the study.
c. The concordance value for dizygotic twins will be 25%.
d. For dizygotic twins, all the variation in susceptibility for the disorder will be due to environmental factors.
e. All the variation in susceptibility for the disorder for monozygotic twins is due to genetic factors.

Answer 1

The correct statement is that for dizygotic twins, all the variation in susceptibility for the disorder will be due to environmental factors.

Step-by-step explanation:

The correct statement is d. For dizygotic twins, all the variation in susceptibility for the disorder will be due to environmental factors.

Concordance value refers to the probability that both twins will have the same trait or disorder. In this case, since the concordance value for monozygotic twins is 100%, it means that if one twin has the neurological disorder, the other twin will also have it.

For dizygotic twins (fraternal twins), who share around 50% of their genetic material like any other siblings born at different times, the concordance value will be different. If the concordance value is 100% for monozygotic twins, it means that all the variation in susceptibility for the disorder for dizygotic twins will be due to environmental factors, as they do not share the exact same genetic makeup.