The Marfan's syndrome (arachnodactyly is often present) is inherited as an autosomal dominant trait with 80 % penetrance.
A normal man married an affected woman.
The wife's relatives: healthy father, affected mother, two affected brothers.
The husband's relatives: healthy father, affected mother, two affected brothers.
Draw a pedigree of this family. What is the probability that their child will be affected?
What is the probability of an affected child birth in the marriage of woman's brother with healthy female?