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Cystic fibrosis is an autosomal recessive genetic disorderresulting from the absence of a functional transmembraneconductance regulator (CFTR) protein. A woman whose older sisterhas a son with the disorder is concerned that she will also have achild with cystic fibrosis. The woman’s husband is healthy but hehad a paternal uncle who died of cystic fibrosis as a teenager.

   A. ​Based on the information given above, draw apedigree for the couple and the extended families described above.Here is some additional information about both families: Woman -has two siblings, the sister with the affected son and a youngerbrother who does not have children. Neither of the woman’s parentsor her siblings have the disease. The sister has a healthy daughterand the sister’s husband is also healthy. Husband – has oneunaffected older brother who has two unaffected daughters. Both ofhis parents are unaffected. His father’s older brother is the unclethat died from cystic fibrosis. Include as many generations andindividuals as you can in your pedigree. For simplicity, assumethat individuals homozygous for a non-functional CFTR protein donot live long enough to reproduce.   

B. What is the probability that this woman and her husbandwill have a child with cystic fibrosis?

Assume that only one of the woman’s parents is a carrier ofthe recessive allele for cystic fibrosis. Also assume that herhusband’s mother has two normal alleles of the CFTR gene.