Until recently, Bertrand Might was the only known patient with a certain genetic disorder. His parents began searching for others. Photograph by Phillip Toledano

Matt Might and Cristina Casanova met in the spring of 2002, as twenty-year-old undergraduates at the Georgia Institute of Technology. Cristina was an industrial-design major with an interest in philosophy; Matt was a shy computer geek obsessed with “Star Trek.” At first, Cristina took no notice of him, but the two soon became friends, and that fall they began dating. Within a year, they were married.

The couple had their first child, a son, on December 9, 2007, not long after Matt completed his Ph.D. in computer science and Cristina earned her M.B.A. They named him Bertrand, in honor of the British philosopher and mathematician Bertrand Russell. After a few blissful weeks, the new parents began to worry. Matt and Cristina described Bertrand to friends as being “jiggly”; his body appeared always to be in motion, as if he were lying on a bed of Jell-O. He also seemed to be in near-constant distress, and Matt’s efforts to comfort him “just enraged him,” Matt says. “I felt like a failure as a father.” When the Mights raised their concerns with Bertrand’s doctor, they were assured that his development was within normal variations. Not until Bertrand’s six-month checkup did his pediatrician agree that there was cause for concern.

By then, Matt had a new job, as an assistant professor at the University of Utah’s School of Computing. It took two months to get Bertrand on the schedule of a developmental specialist in Salt Lake City, and the first available appointment fell on the same day as a mandatory faculty retreat. That afternoon, when Matt was able to check his phone, he saw that Cristina had left several messages. “I didn’t listen to them,” he told me in an e-mail. “I didn’t have to. The number of them told me this was really bad.”

Bertrand had brain damage—or, at least, that was the diagnosis until an MRI revealed that his brain was perfectly normal. After a new round of lab work was done, Bertrand’s doctors concluded that he likely had a rare, inherited movement disorder called ataxia-telangiectasia. A subsequent genetic screen ruled out that diagnosis. When Bertrand was fifteen months old, the Mights were told that urine screening suggested that he suffered from one of a suite of rare, often fatal diseases known as inborn errors of metabolism. During the next three months, additional tests ruled out most of those ailments as well.

As Matt tried to get a foothold in his new job, Cristina struggled to care for a wheelchair-bound child whose condition seemed to worsen by the day. When Bertrand was hospitalized, she would stay by his bedside, often neglecting to eat; the constant stress contributed to osteoarthritis so severe that her doctor told her she’d need to have her right knee replaced. In April of 2009, the Mights flew to Duke University, in Durham, North Carolina, to meet with a range of specialists, including a geneticist named Vandana Shashi, whose clinical practice focusses on children with birth defects, intellectual disabilities, and developmental delays. After five days of tests and consultations, the Duke team told the Mights that there was widespread damage to Bertrand’s nervous system and that some of his odd behavior—wringing his hands, grinding his teeth, staring into space—was likely due to the fact that his brain appeared to be suffering from spikes of seizure-like activity.

When Bertrand was a newborn, Matt joked to friends that he would be so relaxed as a parent that he wouldn’t care which technical field his son chose to pursue for his Ph.D. In May of 2009, the Mights closed Bertrand’s college savings accounts so that they could use the money for medical care. That fall, Bertrand was rushed to the emergency room after suffering a series of life-threatening seizures. When the technicians tried to start an I.V., they found Bertrand’s veins so scarred from months of blood draws that they were unable to insert a needle. Later that evening, when Cristina was alone with Matt, she broke down in tears. “What have we done to our child?” she said. “How many things can we put him through?” As one obscure genetic condition after another was ruled out, the Mights began to wonder whether they would ever learn the cause of their son’s agony. What if Bertrand was suffering from a disorder that was not just extremely rare but entirely unknown to science?

In September of 2012, I visited the Mights in Salt Lake City, where they lived in a two-story brick Craftsman bungalow. Matt wore a striped Brooks Brothers polo shirt and jeans; with a neatly trimmed beard and shoulder-length brownish-blond hair, he brought to mind Björn Borg of the late nineteen-seventies. Cristina, who is five feet ten, with porcelain skin and long black hair, greeted me with a hug and a wry smile.

In early 2010, the couple had decided to try to have a second child. This was a gamble: if Bertrand’s condition was indeed new to science, there was a chance that it was caused by a spontaneous, or de novo, mutation in the egg or sperm cell, and was not in Matt’s or Cristina’s DNA. On the other hand, if the condition had a genetic history, the Mights could pass it on to other children. That summer, Cristina learned that she was pregnant, and on April 14, 2011, she gave birth to a girl, Victoria. Within minutes of the delivery, Matt and Cristina knew that their daughter was healthy; she moved with a fluidity that Bertrand never had. When I arrived at the Mights’ house, Victoria was bouncing around and grabbing at her mother’s sleeve. “Victoria, you need to wait for Mommy to say hello,” Cristina said. To me, she added, “I had no idea how easy we had it with Bertrand.”

Bertrand, who was four at the time, was on the floor in the playroom, around the corner from the kitchen. He had round cheeks and a mop of brown hair. As with many children with genetic disorders, he also had some mild facial abnormalities: his eyelids drooped, and his nose was smaller than is typical, with an indentation on the bridge and slightly upturned nostrils. Two years earlier, the Mights had noticed that Bertrand didn’t produce tears; every time he blinked it was as if sandpaper were scraping against his corneas. To keep the resulting scar tissue from causing permanent blindness, Matt and Cristina put medicated drops and lubricating ointment in Bertrand’s eyes every few hours, which made the skin around his eyes look as if it had been rubbed with Vaseline. Because Bertrand doesn’t reflexively align his head with his body, his face was often pointed away from where he was trying to look, and he ground his teeth with such force that it sounded as though he were chewing on rocks. Yet the Mights told me that, for all of his medical issues and his many hospitalizations, he seemed oddly immune to more ordinary ailments, such as colds and allergies.

I had brought each of the kids a small plush doll; when I placed Curious George on Bertrand’s stomach, Victoria grabbed hold of Harry the Dirty Dog. When Cristina went to get something in the kitchen, she warned me not to let Victoria bite her brother. “She doesn’t understand that Bertrand just can’t interact with her the way everybody else can,” she said. “So she gets frustrated and does everything she can to get his attention.” Later, when I was lying on the floor with Bertrand and Victoria teetered into view, he seemed to flinch.