When David Fajgenbaum's mother died of brain cancer, the Georgetown University student founded Students of Ailing Mothers and Fathers in 2007 to cope. Now a doctor who's been diagnosed with a rare and deadly disease, he's founded another organization, the Castleman Disease Collaborative Network, where he works with fellow patients to advance understanding of the disease.

But he barely made it to this point; after a 2010 flu-like illness that landed him in an ICU for six months and got so bad his last rites were read to him, the then-medical student was diagnosed with a subtype of an immune system disorder known as Castleman disease, reports CBS News.

In spite of multiple relapses, he graduated in 2013 and went on to earn his MBA in 2015. "At the heart of this, I’m a patient and also an investigator," says Fajgenbaum.

"We, as patients—well, no one wants to figure out what is going on with diseases as much as the patients do." Around 7,000 people are diagnosed with Castleman disease every year in the US, according to the University of Pennsylvania, where Fajgenbaum went to med school and is now an assistant professor of medicine.

Thanks in large part to his research, it's now understood that the "multicentric" subtype involving multiple regions of enlarged lymph nodes is triggered by the immune system overreacting, per a post at Phys.org.

Now Fajgenbaum and 14 patients are sequencing their whole genomes to look for which genes are the culprits. Fajgenbaum ultimately hopes to find a drug that "works for every single patient with Castleman disease." (Few kids fully recover from this rare disease.)

This article originally appeared on Newser: Doctor Now Studying Rare Disease That Nearly Killed Him