The boy was dying. Zebrafish helped save his life

The boy was quickly running out of options. His legs and belly were swelling like sponges, his lungs kept filling with fluid so badly that he needed an oxygen tank, and the extreme measures his physicians had tried worked only temporarily.

“He got worse and worse and worse,” said Dr. Hakon Hakonarson, a pediatric lung specialist and director of the Center for Applied Genomics at Children’s Hospital of Philadelphia (CHOP). “He was going to die.”

But the boy lived. Born with a rare, complex genetic condition, he owes his life to zebrafish, the nearly transparent creatures that have become the go-to lab animal in countless studies of genetics, development, and disease.

Hakonarson and his colleagues identified the mutation causing the boy’s illness, in