The genotype is defined as a set of genes in our DNA which are responsible for a particular trait. Two organisms that are carbon copy of each other, but if they have the slightest difference, that is because of different genotypes.
She must have at least one color blindness allele. Because color blindness is a sex-linked gene (present on the X chromosome), the mother must carry an allele.
She can't get it until she has two alleles, thus the second choice is incorrect. Her son just needs one allele to be affected.
Because she might be homozygous recessive for the gene, the third option is incorrect. Her son can inherit the gene if she carries one or more alleles.
She must be a heterozygous carrier of the gene; otherwise, she will be unable to pass it on to her son. She must carry a colorblind allele.
The red-green color blindness is a recessive X-linked trait. The females are not affected unless both the X chromosomes have the affected allele. Mostly, the females are the carriers, and the males are affected as they have only one X chromosome. In the given pedigree, the father of Irene have the normal allele, while her mother is a carrier.
However, Irene is neither a carrier nor affected. This means that she carries normal alleles on both X chromosomes. Hence, her allele combination is .
A pedigree depicts familial links and identifies which members of a family have particular genetic pathogenic variations, features, and illnesses, as well as their vital state.
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