Question

A child having two heterozygous parents with a dominant genetic disorder has with chance of inheriting that disorder? Explain your answer.

Response should be minimum 300 words

Answer 1

Answer: - Short answer to this question is 75%. When a trait is dominant, only one allele is required for the trait to be observed, because the dominant allele will mask the recessive allele's character if present. Let us suppose that the dominant allele, in this case, is denoted by 'A' and the recessive is denoted by 'a'. Since each parent provides one allele, the possible combinations are AA, Aa, and aa. A Punnett square can be used to determine all possible genotypic combinations in the parents. Since in this case both the parents are heterozygous for the dominant genetic allele it means that their genotype accordingly will be 'Aa'. Now if both parents are heterozygous (Aa) for the disorder then it will result in the offsprings having the genotypes as 1 'AA', 2 'Aa', and 1 'aa'. I am posting a screenshot of the Punnett square for better understanding.

As can be seen in the picture above 3 out of 4 offsprings will have the dominant allele for the disorder present. Offspring whose genotype is either AA or Aa will have the dominant trait expressed phenotypically, while aa individuals express the recessive trait. So in case of a dominant genetic disorder, the chance of inheriting the disorder is 75%.