One day in August, a few weeks after lightning struck the Beishes’ house, Hollie and Conner were working on a puzzle. “What color is this?” Hollie asked, holding up a blue piece. Her son was silent. She asked again, this time more slowly. Conner stared at her and still said nothing. “He was looking at me like, What do you want me to do?” Hollie recalled.

The Beishes didn’t think the seizures had anything to do with Conner’s speech delay, which had remained static for months. He still had his small arsenal of vocabulary, and he could parrot what his parents and speech therapist said. He would answer his mom when she pointed at things, even if the words he used for them weren’t exactly right: “Moo” was cow, for example, and “meow” was cat. He knew his colors, too, especially red, green, and blue.

That night, after her family went to sleep, Hollie poured herself a glass of soda, sat down with her iPad, and Googled “small cerebellum.” The conditions that popped up were terrifying. There was Alzheimer’s, which she knew Conner couldn’t have, and fatal childhood brain disorders, which she couldn’t stand to think about. Then Hollie saw cerebral palsy listed. “I always thought that was something that happened at birth,” she said. “But one article I read said it’s hard to tell in some kids until they’re older.” If Conner had cerebral palsy, the Beishes could handle it. They knew a few kids with the condition. Her eyelids heavy, Hollie clicked off her tablet and went to bed feeling hopeful.

The good news didn’t last long, however. During the February appointment, Conner had an MRI. The test revealed that his cerebellum, the part of the brain responsible for balance and coordination, was unusually small. “Some doctors said it could be a normal thing, like some people just are born with a small cerebellum,” Hollie said. “Another doctor said it could mean it had changed and had become smaller as he got older.” They would need to run more tests.

Two months later, the Beishes took Conner to a clinic in Baltimore for an electroencephalogram, which measures brain activity through electrodes attached to the scalp. The results were abnormal: He endured multiple seizures during the procedure, some so small that his body never visibly moved. Conner was prescribed a low dose of an anti-seizure medication, which seemed to work. By the time of his follow-up appointment in February 2016, he’d been seizure-free for three months. He was even able to ride a scooter, a Christmas present from his parents, in the backyard with Jaxon.

At the hospital where Conner had been rushed in an ambulance, doctors ruled out an infection like meningitis. Then they sent him home. “It could happen again, or it might not happen again,” one of them told Hollie. If it did, she shouldn’t worry. About 470,000 children in the United States have epilepsy, according to the Centers for Disease Control and Prevention, but an underlying medical condition isn’t the only cause of seizures. High temperatures can also trigger an episode in a developing brain. The doctor told Hollie that Conner had likely experienced one of these so-called febrile seizures and instructed her to give him Tylenol.

When the school called Hollie, she jumped in her dark purple Ford SUV and resisted the urge to speed. “I even put the car on cruise control,” she said. She also forced herself to stop crying, because the tears were blurring her vision. She didn’t want to get into an accident.

Conner started preschool at three. When picture day rolled around, on October 1, 2015, Hollie dressed him in khaki pants and an OshKosh collared shirt with white and beige stripes. She noticed that he seemed tired. At school, Conner sat for his picture against a blue background that matched his eyes, offering the photographer a measured, close-lipped smile.

“Eat! Eat!” he would yell when he was hungry. Hollie would take him to the pantry or fridge and point to various food items. He would nod or gesture at what he wanted. “It was a bit like negotiating,” Hollie explained. If Conner didn’t know a word, he would make a sound instead—imitating the sucking of liquid through a straw if he was thirsty, for instance. Some words he understood but couldn’t quite say: Jaxon was “Bubba,” Jeff was “Da,” and Hollie was “Me.”

Hollie was in her late twenties then, five-foot-three with green eyes and a silver hoop through the inner cartilage of one ear. Jeff was a few years older, was much taller, and liked to wear baseball caps backward. They’d met ten years prior at a Walgreens, where she’d worked as a clerk and he’d made regular drop-offs driving a Coca-Cola delivery truck. Hollie had decided to be a full-time mom, which suited her “strict and structured” personality, she told me. It also meant that she was the person who adapted the most to Conner’s limited communication.

Words came slowly to Conner. By his second birthday, he’d mastered about ten of them; at that age, the number should have been at least 50. “I assumed it was because Jaxon would always speak for him,” Hollie said, something big brothers often do. “Sometimes I thought maybe he was just shy.” The Beishes’ pediatrician said not to worry, that some children gain words in bursts. Family and friends were also reassuring. “They would joke that once he started talking, he wouldn’t stop,” Jeff recalled. Months passed and Conner’s progress was still glacial. The Beishes took him to a speech pathologist.

Born in August 2012, Conner had been a healthy infant. He was prone to colds and had “baby asthma,” but the doctors said that would go away. By the time he turned one, he had a full head of wavy blond hair that Hollie kept long. Sometimes it fell down his forehead, meeting the long brown eyelashes that framed his blue eyes. He had a wide, mischievous smile. He started walking at 13 months and two months later was chasing Jaxon around the house dressed as a lobster for Halloween.

Which would have been fine, except that Conner was sick. He had been for months, and the cause was a mystery. He got worse at the hotel. The Beishes hoped that the elusive condition wasn’t serious and they’d find the right treatment soon. Certainly, they reassured themselves, it was nothing catastrophic. After all, the cliché is that lightning never strikes the same place twice.

“Thank God it happened during the day and not while we were asleep,” Hollie, Jeff’s wife, added. She and the Beishes’ other son, seven-year-old Jaxon, had been out running errands. By the time they got home, firefighters had extinguished the flames. The house was salvageable, but electrical wiring needed to be rerouted, and floors and walls required structural repairs. The Beishes spent the next month at a nearby hotel.

Chapter Two

Emily de los Reyes had two career choices. “All the women in my family were teachers or doctors,” she said. De los Reyes was born in 1963 and grew up in Manila. Her family was well off, so they didn’t feel the most acute effects of the Philippines’ widespread corruption and privation, the fallout of President Ferdinand Marcos’s dictatorship. When de los Reyes went to medical school, however, she witnessed social ills firsthand. On Sunday afternoons, following church, she sometimes assisted health workers caring for children in poor parts of the city. Hundreds of kids would queue up—some with parents, some on their own—and wait to be seen. The experience stayed with de los Reyes as she pursued a career in pediatrics.

Toward the end of medical school, in the mid-1980s, she joined her classmates in protesting the waning Marcos regime. When I met her at a busy Starbucks in Columbus, Ohio, more than 30 years later, it was hard for me to imagine her as a firebrand. At 54, she was the picture of precision. Her hair had been blow-dried into a neat black bob and showed a few streaks of gray. Nearly everything she had with her was a shade of pink: her laptop cover, her iPhone case, her zip-up sweater. Before I arrived, she’d been carefully finalizing a PowerPoint presentation. “I was so idealistic back then,” she said of her youth, a smile creeping across her face.

After graduating she decided to work in the United States, because its democracy was strong and medical care first-rate. She moved to San Francisco, where there was a large Filipino community, then to Charleston, West Virginia, where there was not. One day, while completing her residency at a local hospital, she rode in a helicopter to pick up a sick infant from a farm. When the mother saw de los Reyes’s dark skin, she hesitated before handing over the baby. Still, the young doctor found a community. Her residency class had several other foreigners—not uncommon in underserved parts of the United States—and she met an American doctor who soon became her husband.

In the early 1990s, West Virginia became a relative hotbed of an infectious brain disease called La Crosse encephalitis. Like Zika, the virus is spread by mosquitoes, and most cases occur in children. Dozens of patients came to the Charleston hospital where de los Reyes worked. Some presented with nothing more than a fever. Others arrived comatose, with terrified parents. “A day or two before, their child was fine,” de los Reyes said, “just running around in the woods.” Then the kid would struggle to wake up, have seizures, and become delirious before passing out. “We would give them anti-seizure medications and make sure they were ventilated,” de los Reyes said. “Most would do fine.” But some would not: They left the hospital with permanent neurological deficits.

De los Reyes decided to specialize in pediatric neurology, a field rife with harrowing conditions that degrade young brains. Many of those ailments are rare diseases, a legal designation that in the United States is generally reserved for illnesses afflicting fewer than 200,000 people. Nearly 7,000 maladies fall into the category. Most are complicated genetic conditions that pharmaceutical companies have never been inclined to gamble on. The industry prefers to focus its resources on widespread ailments with identifiable causes, an approach that requires less research investment and offers a larger stable of patients who will eventually pay for the pills, injections, and devices that companies invent. A U.S. law called the , signed in 1983, offers tax breaks, subsidies, expedited approval, and to companies that develop treatments for uncommon conditions. The law led to the creation of hundreds of new drugs in its first three decades on the books. Still, when de los Reyes entered pediatric neurology, 95 percent of rare diseases had no cure. Over the course of her career, that number would hardly budge.

After finishing her residency and a fellowship, de los Reyes was recruited to work as a neurodevelopmental specialist at the University of Arkansas at Little Rock. It was there, in 2001, that she saw a case unlike anything she’d ever treated. The patient, referred by an ophthalmologist, was a nine-year-old girl who’d been born healthy but was now losing her eyesight. Her family was from Guam. They’d traveled more than 7,000 miles for the appointment at the Little Rock hospital, which through word of mouth they’d learned had excellent eye specialists.

De los Reyes examined the little girl, who had a chubby, tamarind-colored face and short black hair—not so different from her own appearance when she was a child in the Philippines. The parents described a bizarre constellation of symptoms on top of progressive blindness: speech delay, seizures, and difficult walking. Together with the ophthalmologist, de los Reyes began testing for various illnesses. The doctors ruled out macular dystrophy, a genetic condition that destroys cells in the retina, and keratomalacia, a chronic deficiency of vitamin A that causes blindness. Could it be a problem with the little girl’s brain, like a tumor? Imaging came back negative for suspicious masses.

Stumped, de los Reyes called her mentor, Paul Dyken, one of the country’s foremost experts in childhood brain disorders. She spelled out everything she’d learned and asked if he’d ever seen anything like it. “Oh Emily…,” Dyken replied with a heavy sigh before delivering the news.

The little girl had a condition so rare that most pediatricians hadn’t heard of it. But Dyken had. He’d treated several patients with, and coauthored scientific papers about, the disease. He was one of the few doctors in the world who could say “I see this all the time” about the condition, because afflicted families sought him out. If she was lucky, Dyken said, the girl would live to be 20. De los Reyes could help her die a slow, inevitable death as painlessly as possible—nothing more.