Question

Huntington's disease is a hereditary ailment caused by a recessive gene. if both parents carry the gene but do not have the disease, there is a 0.25 probability that an offspring will fall victim to the condition. a newly wed couple find through genetic testing that they both carry the gene (but do not have the disease). if they intend to have five children, find the probability of each event.

Answer 1

Getting the probability for each event can easily be done using Punnett Square (say, Hh x Hh for the couple since they are both carriers of the disease). Doing so will result to: 0.25 probability of an offspring not having the disease and is not a carrier of the gene, 0.50 probability of an offspring not having the disease and is a carrier of the gene, and a 0.25 probability of an offspring having the disease. The probability of these events apply to each offspring, and will not depend on how many children they want to have. This means each offspring has a 0.25-0.50-0.25 chance of not being a carrier, being a carrier, and having the disease, respectively.