Answer to Question #165674 in Genetics for Virat

Question

3) A 3-year-old boy, was sent to a dermatology clinic due to a pronounced sensitivity to sunlight and the

appearance of multiple skin spots. Clinical examination revealed photophobia, conjunctivitis and significant

lentiginous hyperpigmentation of unprotected from the sun skin surface; otherwise, its development and

inspection data were normal. Child-patient is from an unrelated marriage.

The dermatologist said that the child has a classic manifestation of pigment xerodermia. To confirm the

diagnosis, a skin biopsy was performed to evaluate DNA reparation. The results of this test confirmed the

diagnosis of pigment xerodermia. Despite appropriate preventive measures, at the age of 15 the child got

metastatic melanoma and died after 2 years. His parents have two other children; no one of them is sick

with pigment xerodermia.

Issues for discussion:

1. What type of reparation is knocked out by pigment xerodermia?

2. What are the molecular mechanisms of reparation of this disorder?

3. Determine the genotypes of parents, all children.

4. Calculate the risk of having sick children in this family.

5. Make a comparative characteristic with photoreactivation.

Answer 1

Sorry the probability should be 1/4 or 0.25, please take note of the updates. Thank you.