GALVESTON — A University of Texas Medical Branch doctor and his identical twin brother are to star next month in a television program on The Learning Channel about a rare case that tested their expertise in immunology.

Both allergy immunology fellows, David Redding of the medical Branch and Alan Redding, of the University of Tennessee-Memphis, will feature in an episode of “Diagnosis X,” about IPEX syndrome, a rare disease that kills infants and toddlers.

The show’s producer thought identical twin doctors would provide an interesting twist for the program’s format, which mixes doctors with actors in drama-documentaries about “brain-teaser” cases that test doctors’ diagnostic skills.

“She asked if we had an interesting case they could use,” Redding said of a conversation he and his brother had with the producer when they first met her during a medical conference in San Diego.

“Alan thought of a recent patient with a rare and difficult-to-diagnose disease, IPEX syndrome.”

The condition, the full name of which is immunodysregulation polyendocrinopathy enteropathy X-linked syndrome, is a recently discovered immunodeficiency disease that’s always fatal by age 2 or 3 — usually by age 12 months — without a bone-marrow transplant.

During the TV show, viewers will learn how the Reddings conducted a test for a mutation in a patient baby’s FOXP-3 gene, which confirmed the baby was suffering from the syndrome.

As a result, the baby had a transplant and now is “doing fairly well,” Redding said.

The child had great-uncles and great-great-uncles who died very young. After a cousin died at a hospital in Memphis in 1979, his case was dubbed a “mystery” in a medical journal article.

“The family agreed to let them use their story for the TV show, with some changes to protect their privacy,” Redding said.

The episode, for which both brothers checked the script for accurate medical terminology, will show that women carry the IPEX syndrome disease on their X-chromosome, but it affects males.

A defect in a certain type of T-cell (white blood cells that fight infections) makes the cells react against the patient himself rather than against foreign microbes.

Patients don’t develop immunological tolerance in their gut, so it remains inflamed and cannot absorb anything properly, the endocrine organs are destroyed by the immune system and patients develop severe skin rashes.

Redding, an Atlanta native who, with his twin, attended the Medical College of Georgia and was an internal medicine resident at the University of South Carolina, said of the program: “It is showing the interesting ‘brain-teaser’ cases where the diagnosis is not readily apparent. It shows how doctors have to go to books — or the Internet nowadays — and review literature.

“It exemplifies that you have to be willing to constantly learn and look things up to make a diagnosis.”

Playing doctors on TV was “not much of a stretch,” he said. The setting is the North Hollywood Medical Center, a hospital that closed in the 1990s and is “an excellent place to shoot medical shows.” The series “Scrubs” is filmed there, on a different floor.

Each one-hour episode of “Diagnosis X” deals with two cases. Thom Eberhart, director of the film “Gross Anatomy,” directed the Reddings’ episode, “Systems Failure,” which took two 13-hour days to make.

“I was surprised at how long it took,” Redding said.

The program will be shown at 9 p.m. on Aug. 1.