KROK 1 2018 – Question 136 · KROK (Medicine) · Biology

Genealogical analysis of a child with myotonic dystrophy determined that this disease is present in every generation, equally presented by the relatives of both genders, the risk of inheriting this disease is equal no matter which parent is affected. If one of the parents is heterozygous for this disease and the other parent is healthy, the risk of them giving birth to a sick child is 50%. What type of disease inheritance is it?

  1. A. X-linked dominant
  2. B. Autosomal recessive
  3. C. Autosomal dominant
  4. D. Y-linked
  5. E. X-linked recessive
Hint

Use the pattern across generations, the equal involvement of both sexes and the transmission risk to decide on the type of locus and how many gene copies are needed.

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