idk

autosomal dominant

1. Unaffected individuals are homozygous for the recessive, wild-type allele.

2. Affected individuals with only one affected parent are heterozygous.

3. Affected individuals with any unaffected children are heterozygous.

4. Affected individuals with two affected parents may be homozygous dominant or heterozygous.

autosomal recessive

1. Affected individuals are always homozygous recessive.

2. Unaffected children of an affected parent are always carriers (heterozygous).

3. Both parents of affected individuals must have at least one recessive allele.

4. If both parents are carriers, their unaffected children may be carriers or homozygous for the dominant, wild-type allele.

5. For rare conditions, you can assume that individuals marrying into a family do not carry the recessive allele if there is no evidence that they are carriers.

You can calculate probabilities in pedigrees by considering the requirements for a specific outcome. In this case, the outcome that individual IV-1 will be affected has four requirements:

1. Individual III-3 is a carrier (probability = 2/3).

2. Individual III-4 is a carrier (probability = 1/2).

3. Individual III-3 passes the r allele to his child (probability = 1/2, assuming III-3 is a carrier, which is accounted for in requirement 1).

4. Individual III-4 passes the r allele to her child (probability = 1/2, assuming III-4 is a carrier, which is accounted for in requirement 2).