Count a 12-year-old Colorado Springs boy among a growing number of people to learn that they suffer from IPEX syndrome.

Doctors have increasingly diagnosed children and young adults - some as old as their early 20s - with the autoimmune disorder, said Troy Torgerson, associate professor of pediatrics and immunology and rheumatology at Seattle Children's Hospital and the University of Washington.

The reason dates to 2001, when researchers published a landmark paper describing the syndrome's link to the FOXP3 gene.

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Shortly after, doctors began testing newborns for the condition when they exhibited certain symptoms. But as researchers' understanding of the disorder grew and genetic testing proliferated, an increasing number of doctors began testing older children and young adults who have long suffered from milder autoimmune diseases, Torgerson said.

"Just really within the last year we've realized that we really need to start thinking about adult GI (gastrointestinal) docs and training them to start thinking about this disease," Torgerson said.

It's an X-linked recessive trait - meaning that it's passed down by the mother, and only affects boys. Males born to a mother with the trait have a 50-percent chance of getting IPEX syndrome.

And R.J. Campos, the Colorado Springs boy, isn't alone in exhibiting only two of the three symptoms typical of IPEX syndrome. About 75 percent of children with the condition do not have diabetes, Torgerson said.

R.J. didn't have genetic testing until he was 12 and his baby brother was diagnosed with the syndrome.

The key to ensuring a diagnosis, though, is sequencing the FOXP3 gene.

"Really, genetic testing is the gold standard for making the diagnosis," Torgerson said.