U.S. doctors online nowAsk doctors free
A 35-year-old member asked:

If both parents must have a mutation in their cf genes in order to create a child with cf, how common are carriers?

2 doctor answers5 doctors weighed in
Dr. Derrick Lonsdale
Preventive Medicine 75 years experience
See below: Each time carrier parents have a child they have one chance in 4 of each passing the mutated gene and having a child with cf, two chances in 4 of each passing it from one parent (carriers) and one chance in 4 of a two normal gene healthy non carrier.This is classical mendelian inheritance but there may be more information now. Remember that it is a 4-sided "penny" that you toss each time!
Created for people with ongoing healthcare needs but benefits everyone.
Dr. James Ferguson
Pediatrics 48 years experience
Difficult question: A pair of the most common defect in the CF gene is responsible for about 80% of cases, but there are dozens of other mutations that can be involved is individual cases.The carrier state in populations varies by ethnic groups. Numbers from 1/27 to 1/50 or so are often sited.Carrier detection is possible through gene testing.
Created for people with ongoing healthcare needs but benefits everyone.
Last updated Sep 23, 2016
Connect with a U.S. board-certified doctor by text or video anytime, anywhere.
$44 video appointments with $19/month membership*
*Billed $57 every 3 months. Cancel anytime.


Content on HealthTap (including answers) should not be used for medical advice, diagnosis, or treatment, and interactions on HealthTap do not create a doctor-patient relationship. Never disregard or delay professional medical advice in person because of anything on HealthTap. Call your doctor or 911 if you think you may have a medical emergency.