Medical genetics: chromosomal disorders, inheritance patterns
Human Anatomy · MBBS
Study notes
A couple has one child with cystic fibrosis; both parents are healthy. Cystic fibrosis is autosomal recessive — the child inherited a faulty CFTR gene copy from each healthy carrier parent. Each future pregnancy carries the same independent odds: 25% affected, 50% carrier, 25% free. The parents' health doesn't change this — carriers show no disease. This 1-in-4 pattern is the signature of recessive inheritance.