David Cry scanned the waiting room at the Kennedy Krieger Institute in Baltimore looking for his future. Instead, he saw what could have been his past: a row of young boys in wheelchairs — their mobility gone, their sight, hearing and lives to follow.

Cry had been stricken with adrenomyeloneuropathy, better known as AMN, a genetic disease that had affected him suddenly in his late 20s. He was searching the waiting room for someone like him, a man with the same condition. He wanted a glimpse of what to expect.

The boys he saw had adrenoleukodystrophy, or ALD, the deadly pediatric form of the disease that destroys the myelin sheath of nerve cells in the brain.

The expert whom Cry was waiting to meet that day, Hugo Moser, put it to him succinctly: “There but for the grace of God goes you,” he told Cry.

“I still see the image of those six boys,” said Cry, now 47. “It never goes away.”

The Slidell man, who would eventually lose the ability to walk, decided then to focus on helping families whose sons suffered from ALD. He created the ALD Foundation and pored over all the research he could find in his quest to be a support and help for devastated parents.

He didn’t know then that he would be one of them.

Cry met Jaymee Godfrey, an Ohio woman, when she reached out for answers about the disease that had killed her father, uncle and two cousins. Her young son, Logan, also had the genetic predisposition for ALD.

For months, the two had long phone conversations, and then Cry flew to Akron to meet Jaymee. He proposed 15 days later.

The three became a family, and in 2008, the couple had a son, Brennan, together.

Knowing the risks, they conceived their child through in-vitro fertilization. An innovative procedure called pre-implantation genetic diagnosis allowed them to make sure the baby would not have the X-chromosome mutation that affected both David and Logan.

As Logan approached his 10th birthday, the couple felt immense relief. The deadliest manifestation of the disease, childhood cerebral demyelinating ALD, occurs earlier in life. They had every reason to believe that Logan had been spared the worst ravages of the genetic malady.

But when Logan turned 12, the couple received a devastating diagnosis. Their son’s latest brain MRI showed that he had adolescent onset of the cerebral disease — itself a rarity.

Cry, who had spent years in close contact with experts, sprang into action. Treatments were available, including a bone marrow transplant, which had been successful in halting the progress of the disease in some patients.

He made the phone calls. But Logan was not a good candidate for a transplant because of the extent of brain damage he had already suffered. He had an 86 percent chance of dying from complications from the transplant.

His parents decided to focus on simply loving Logan in the time they had left, “to express our love to our son every day,” he said.

What followed were 31 emotionally draining months, chronicled in the book that Cry began writing in the early days of Logan’s illness, “A Short Walk Home.”

The first sign that Logan was beginning to suffer dementia was his pacing back and forth, an action that soothed him, Cry said.

As he continued to regress, his behavior and decision-making became more erratic, and the couple had moments of panic.

One evening when Cry couldn’t find Logan in the house or yard, he heard his voice from overhead: “Dad? I’m scared.” The boy was on the neighbor’s roof.

Logan had to be watched constantly to prevent his wanderings. He ran away from his mother at a store. Another time, he wandered toward a boat launch and was brought home by a sheriff’s deputy.

Cry chokes up when he recounts the last time Logan said, “I love you, Dad.” The disease soon robbed him of his ability to express himself or to be aware of what was going on around him.

But even when Logan had lost his sight and hearing, he always responded when his mother entered the room, turning toward her and smiling.

“I don’t think I knew what love was until I saw Logan and Jaymee,” Cry said, describing a closeness that was clear even before Logan’s illness began. Logan was a warm and affectionate child who loved to snuggle with his mom.

“If Logan could have survived on Jaymee’s love, he would have,” his father said.

For Cry, living through Logan’s illness and death has made him more determined than ever to help researchers unravel the mysteries of a disease that is metabolic, neurological and endocrinological.

The root of the problem is a mutation on the X chromosome, which means that boys, who have one copy of the gene, are most profoundly affected.

ALD affects one in 18,000 people. Those with the mutated gene have abnormal accumulations of saturated very-long-chain fatty acids in the serum and tissues of the central nervous system. Most men and boys who have the gene also have Addison’s disease, a disease of the endocrine system that results in insufficient amounts of adrenal hormones.

Cry wants to understand why, for some, the gene mutation means illness and death at age 4, but for others, loss of mobility as a young adult. For about 10 percent, Addison’s disease is the only sign of the disorder.

When Logan died, Cry said, his wife grabbed his arms and said, “It’s your responsibility to see that no other kids have to go through what our baby went through.”

It’s a mission that Cry has embraced as he works to support research into the disease. He is also an advocate for newborn screenings for the gene because early diagnosis increases the chance of treatment.

He points to PKU, another genetic metabolic disorder, that is routinely screened in newborns. Two states, New York and Illinois, screen for ALD.

The U.S. Department of Health and Human Services’ Advisory Committee on Heritable Diseases in Newborns and Children met last month and voted to recommend that ALD be included in the uniform screening panel, Cry said. HHS Secretary Sylvia Mathews Burwell has 120 days to act on that recommendation. Cry hopes to see the screening become routine in all 50 states within the next five years.

The year after Logan’s death, state Rep. Kevin Pearson, R-Slidell, attempted to get ALD screening in this state, introducing a resolution to require that it be added to newborn screening as soon as it was recommended by the advisory committee. But in the end, all that was adopted during the 2014 session was a resolution directing the state Department of Health and Hospitals to study the health benefits and costs of screening for ALD.

Cry also continues to talk to families coming to grips with ALD, something that he acknowledges is harder following his own family’s tragedy.

But doing so remains important to him.

“Whatever you have, you have to own it,” he said.

Follow Sara Pagones on Twitter, @spagonesadvocat.