pgEd has been following a recent controversy in California over a school district’s decision to transfer a student, who is reported to carry a mutation for cystic fibrosis (CF)*, to a new school to segregate him from other students who have cystic fibrosis. CF is a genetic condition and therefore is not contagious; however, there are concerns that people with CF in close contact with each other might share bacteria that could worsen their symptoms. The parents are seeking to overturn this decision, arguing that their son has never been diagnosed with cystic fibrosis or exhibited any lung symptoms.
This story was featured in the San Francisco Chronicle as well as a number of other media outlets and has prompted a statement from the Cystic Fibrosis Foundation. It has raised a number of issues that are central themes in the pgEd lessons. Our lessons prompt students to think about the potential impacts of knowing more about their genetic make-up, encouraging them to consider the perspectives of multiple stakeholders to explore how different priorities and concerns shape their viewpoints.
* We do not know any details about this student’s genetic make-up (also referred to as his “genotype”) beyond what was reported. This story has brought up a number of questions about the genetics of cystic fibrosis that we will address below.
Everybody has two copies of the CF gene (except possibly in rare cases), whether or not they have this condition. There are mutations in the CF gene that have been found to cause CF, but only if present in both copies. If present only in one copy, these mutations do not cause CF; these individuals are called “carriers” because they can potentially pass this variant on to their children.
Over 1,800 genetic changes (also called variants or mutations) have been found in the CF gene. (Note: A mutation is simply a change in DNA sequence, neither good nor bad.) Some of these have been found to cause CF if present in both copies, some are neutral and do not cause CF, and some are uncertain meaning that it is not yet known whether or not they cause CF. This is one of the major challenges in personal genetics. While personal genome sequencing could reveal your genetic variation (changes in your DNA sequence), it is often unknown at this point in time how these genetic changes will affect your health and other traits. This is one of the major goals of research in this area.
To learn more about the genetics of cystic fibrosis, visit the Cystic Fibrosis Foundation website.