If your dad has cystic fibrosis does it mean you will?

We all have pairs of genes in our DNA makeup. We inherit one set of genes from our mother and the other set from our father. Cystic fibrosis is a recessive genetic condition. This means that you must have two defective genes, one from your mother and one from your father, to inherit cystic fibrosis. If you have only one defective gene from one parent, you are a carrier of the condition. Carriers do not show any symptoms of cystic fibrosis but they can pass on the defective gene to their offspring. Therefore, the chance of having cystic fibrosis depends on the genetic makeup of both of your parents [source: PubMed Health].

So, if your father has two defective genes and your mother has one defective gene and one healthy gene, you have no chance of inheriting cystic fibrosis. You do have, however, a hundred percent chance of being a carrier, since you will inherit one defective gene from your dad. If, however, your father has two defective genes and your mother has one defective gene, you have a 50 percent chance of inheriting the condition [source: Lucille Packard Children's Hospital at Stanford].

Cystic fibrosis is most common in Caucasians of European descent. The condition occurs in 1 out of every 3,000 live births. Approximately 25 percent of this ethnic group are carriers for the condition, making it the most common genetic disorder. If cystic fibrosis occurs in your family, you may want to consult a genetic counselor for genetic testing. Genetic testing simply involves a cotton swab of your inner cheek. Most genetics labs test for 30 to 100 different mutations of the cystic fibrosis gene with very good accuracy [source: Lucille Packard Children's Hospital at Stanford].

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