Question

The brother of an unaffected female has cystic fibrosis. Her husband has no family history of cystic fibrosis. What is the probability that her child ha inherited the cysic fibrosis? give reason

Answer 1

• An offspring in this scenario has no chance of inheriting cystic fibrosis.
• Because, pair of genes present in human DNA makeup. Humans inherit one set of genes from mother and the other set from father.
• Cystic fibrosis is a recessive genetic condition and appears in humans who have two defective genes. Therefore, the chance of a child having cystic fibrosis depends on the genetic makeup of the parents.
• Though the brother of this mother has Cystic fibrosis, she may not have the disease or she may be the carrier with one set of gene, if she has only one defective gene from one parent.
• Carriers do not show any symptoms of Cystic fibrosis but they can pass on the defective gene to their offspring.
• In this case, there is no family history of Cystic fibrosis in the father. So, he cannot pass the defective gene to the child. So, the child has no chance of inheriting Cystic fibrosis.