To determine which individuals have the recessive disease A, we need to understand the genotypes. Since disease A is recessive, an individual will have the disease if they possess two lowercase 'a' alleles (i.e., the genotype 'aa').
Let's analyze each genotype for every family member:
1. Mom: Genotype 'Aa'
- This individual has one 'A' allele (dominant) and one 'a' allele (recessive). Since they have an 'A' allele, they do not display the disease but are carriers of the recessive allele.
2. Dad: Genotype 'Aa'
- Similarly to Mom, this individual has one 'A' allele (dominant) and one 'a' allele (recessive). They do not have the disease but carry the gene.
3. Child 1: Genotype 'aa'
- This child has two 'a' alleles (recessive). Therefore, child 1 will have the disease because both alleles are recessive.
4. Child 2: Genotype 'Aa'
- This child has one 'A' allele (dominant) and one 'a' allele (recessive). The presence of the dominant 'A' allele means that child 2 does not have the disease but is a carrier.
5. Child 3: Genotype 'AA'
- This child has two 'A' alleles (both dominant). As both alleles are dominant, child 3 does not have the disease and is not a carrier.
6. Child 4: Genotype 'aa'
- This child has two 'a' alleles (recessive). Therefore, child 4 will have the disease because both alleles are recessive.
Based on these genotypic results, the individuals who have the disease (with genotype 'aa') are:
- Child 1
- Child 4
Therefore, the correct answers are:
- child 1
- child 4
