Below you have information regarding three different diseases.Evaluate the information given in each paragraph, discuss:
1) Is this a single gene inheritance or multifactorialdisease?
2) Is there a strong genetic or environmental cause to thedevelopment of this disease? If both genetic and environmentalcauses are implicated, you have to indicate each of themseparately.
You have to use the information given in the paragraph todefend your answer. This can be done by underlying the sentencefollowed by brief explanation in the blank space.
a. Age related macular degeneration shows concordance inmonozygotic twins of 37% and 19% concordance in dizygotic twins.First-degree relatives of patients are at a 4.2-fold greater riskfor disease compared with the general population.
b. Severe congenital deafness is caused by loss-of-functionmutations in GJB2. Two carrier patients have one chance in fourwith each pregnancy of having a child with congenitaldeafness.
c. Obesity can be determined by one’s body mass index (BMI). Astudy on monozygotic and dizygotic twins suggests that monozygotictwins reared apart have 0.70 pairwise correlation (similar toconcordance) and monozygotic twins reared together have 0.74pairwise correlations. In addition, dizygotic twins reared aparthave 0.15 pairwise correlation whereas dizygotic twins rearedtogether have 0.33 pairwise correlation.
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