Question

Lynch syndrome is an inherited condition associated with an increased risk for colon cancer, as well as certain other cancers Mutations in one of several genes involved in DNA repair during DNA replication have been associated with Lynch syndrome. DNA sequencing was performed for an individual. The results indicated that the individual carries one of the dominant aleles that has been associated with Lynch syndrome. Which of the following best explains how the results should be interpreted?
(A) The individual does not have an increased risk of developing cancer because one dominant allele is insufficient to cause the disease
(B) The individual has an increased risk of developing colon cancer
(C) Because the person's DNA has the mutation, other family members must have cancer.
(D) Results cannot be interpreted until testing determines if additional mutated alleles are present

Answer 1

Answer:

B. The individual has an increased risk of developing colon cancer.

Explanation:

The presence of mutations associated with this syndrome increases the probabilities to have colon cancer

Answer 2

Answer:

A) The individual does not have an increased risk of developing cancer because one dominant allele is insufficient to cause the disease.

Generally  Lynch S. inheritance is an autosomal  dominant disorder.

Naturally, everybody has the  two copies of gene involved in Lynch .S , inherited from both parents, and the two copies must be mutated to  increase chances of cancer.

Thus  an individual  who carries  one mutated  dominant  gene for Lynch .S from either parent, will not have  cancer.Cancer will only develop when the  mutation affected the second working gene copy, so that it can not work properly to repair DNA.

Thus the two genes are mutated.This second mutated  gene will only be present in the cancer tissues only and not in the entire body.

Therefore the option A, is the right answer because a dominant gene is not required to developed cancer.Two mutated  copies are needed