Credit: Ron Tom/ABC Family Channel © 2010 Disney ABC Television Group Photo: Meredith and Derek on Grey's Anatomy February 24, 2011

In this week's episode of Grey's Anatomy the docs of Seattle Grace Mercy West put an end to a relationship for the sake of the physical health of both parties involved. Ricky and Julia have cystic fibrosis and were thus a danger to each other's well-being. It made for powerful drama, but is it based in fact?

Cystic fibrosis, or CF, is an inherited disease caused by a defective gene. (1 in 29 Caucasian Americans carry the gene, but a person has to inherit it from both parents to develop the disease.) It causes the body to generate extremely thick mucus which accumulates in the lungs and pancreas, causing respiratory and digestive problems. Symptoms include lung infections, chronic coughing, wheezing, poor growth, and weight gain.

Fifty years ago, CF patients wouldn't live past childhood, but now, with advances in treatments and medications, CF patients can live well into adulthood and even middle-age. Currently, 70,000 people worldwide have the disease, and 1,000 more cases are diagnosed every year.

The sad but true news is that cystic fibrosis patients do pose a threat to each other. That's because they carry specific types of antibiotic-resistent bacteria in their lungs that, if swapped, can cause lung infection. And chronic infection leads to lung damage which can shorten a CF patient's life span. Obviously, the best way to prevent cross-infection is to keep CF patients at a safe distance from each other and to discourage the sharing of objects. Hospitals and doctor's offices also follow special guidelines to prevent cross-infection. However, many CF patients are calling all of these practices into question, saying they do more psychological harm than physical good. As we saw with Ricky and Julia last night, the rules can seem awfully heartless.

Sources: Cystic Fibrosis Foundation, Grey's Anatomy Medical Case File, PubMed Health