Doctors use sick boy's DNA in diagnosis, treatment

MILWAUKEE — Doctors and scientists in Wisconsin have published the first detailed account of a groundbreaking medical case in which they sequenced all the genes of a very sick young boy from Monona, Wis., and used the information to treat the child.

Genetic experts said the Wisconsin case signals a new era in medicine in which doctors will be able to read our genetic script to diagnose and sometimes treat maladies, especially cancers and rare hereditary diseases.

The boy, whose story is the subject of a Milwaukee Journal Sentinel series starting Sunday, suffered from a disease and mutation never before seen in medicine. When he ate, painful holes called fistulas would open, leading from his intestine to his skin. The child, now 6, became so sick that doctors had to remove his colon in 2009.

In a paper published online Friday in the journal Genetics in Medicine, doctors and scientists at Children's Hospital of Wisconsin and the Medical College of Wisconsin described how they were able to read the boy's genetic script in 2009 and pinpoint the mutation responsible for his disease.

The case is believed to be one of the first in the world in which the sequencing of a patient's DNA has led to a diagnosis and treatment.

The Wisconsin case shows how, with a patient's life at stake, doctors, geneticists and computer experts can work together to make sense out of the vast ocean of information in our 21,000 genes.

"It's a wonderful paper," said Eric Green, director of the National Human Genome Research Institute, part of the National Institutes of Health. "It seems like every month now there's a publication like this that demonstrates the power of this technology."

As a result of sequencing, the Wisconsin scientists learned that the boy had a defect in his immune system caused by a single mutation in a gene called XIAP. The mutation also caused a second extremely rare disease called XLP, which affects just 400 boys worldwide, rendering them unable to survive Epstein-Barr virus.

Doctors had not previously known that the child had XLP, which can be treated with a bone-marrow transplant. In mid-July the boy received an umbilical-cord blood transplant, which is similar to a bone-marrow transplant. He was discharged from the hospital in October.

As the doctors point out in their commentary, the new case underscores how the fast-moving revolution in technology is driving breakthroughs in genomics.

"The tools available to make this diagnosis," they write, "were not available when the child first (was hospitalized) four years ago."