A Man Who Is a Carrier for Cystic Fibrosis and for the TGFB1

Essay

A man who is a carrier for cystic fibrosis and for the TGFB1 modifier gene has a child with a woman who is also a carrier for cystic fibrosis but has two copies of the recessive allele for the TGFB1 modifier.What percentage of their children will have cystic fibrosis AND express the recessive modifier? Show your Punnett square.