As her former teammates pressed on through the most trying cross country season of their careers, Jenna's mother, Lisa Parlette, began to search for answers.

Why had Jenna gone down? Why didn’t she wake up? What caused her to battle so many health issues during her lifetime?

While doctors still have yet to officially diagnose the underlying cause of Jenna’s health issues, the most likely culprit is mitochondrial disease.

The disorder affects the metabolic processes of the body’s cells, resulting in growth deficiencies, seizures, and a weakened immune system. Long-term effects include malfunctions in major organ systems from the heart to the kidneys to the liver.

Doctors oftentimes overlook mitochondrial disease. Its symptoms coincide with other diseases and disorders that are more common and easier to diagnose. Many patients with mitochondrial disease are never diagnosed until after death.

There is no cure. Some patients are confined to a wheelchair. Others deal with increased susceptibility to prolonged illness.

However, some patients see their quality of life improve through physical therapy, treatment of individual symptoms, and taking over the counter supplements to aid mitochondrial functions.

The DNA and blood samples from Jenna and her family remain at Indiana University’s Metabolic Genetic Counseling Center in Indianapolis. Testing the samples can be costly – insurance usually does not cover tests on a patient who is already deceased – but geneticist Dr. Matteo Vatta and genetic counselor Katie Schumacher took an interest in the family’s case and waived the usual fees. Their goal is to find the answers that Lisa has been searching for.

A true diagnosis could come tomorrow or 10 years from now depending upon progress from mitochondrial disease research hubs in Cleveland and Pittsburgh. While mitochondrial disease is at the top of the list of possible diagnoses, other metabolic disorders including channelopathy – the disruption of the ion channels in each cell that can cause seizures, heart issues, and other maladies – are still in play.

On such a brutal day to run, why was Jenna allowed to compete – especially given her medical history?

That question haunted Combs in the weeks and months following Jenna’s death. Reporters from newspapers and television stations brought it up delicately in interviews. Posts on some running website forums were much more incisive and blunt.

But running was more than Jenna’s passion; it was in her soul. To Lisa, running didn’t end her daughter’s life – it extended it. It made it full. It made it joyous. It made it Jenna’s.

Schumacher said there is some truth to those claims. Patients with neuromuscular diseases are encouraged to exercise to build up strength and stamina in muscles weakened by the disorder.

“I don’t think anyone would disagree that Jenna would fall into the category of an elite athlete,” Schumacher said. “Jenna had a lot more determination to be great at her chosen sport. Her muscles seemed to be less impacted than most of our [patients with mitochondrial disease].”