She's sleeping now, this 19-month-old girl with curls the color of butterscotch. Her soft white blanket with colorful dots is pulled up to her waist.

She shares a room with her 3-year-old brother, her crib on one wall, his toddler bed on the other, a bookshelf full of books, a TV playing "Frozen," her new favorite, and six butterfly wall hangings, all purple.

Butterflies. The symbol for Dravet Syndome, a rare neurological disease that causes frequent seizures, often life threatening.

Mackenzie Boswell was diagnosed with the disease a year ago.

Sleep. Heat. Too much brain activity. Those are the known events that bring on seizures, which can last 30 minutes or more. Thirty minutes of twitching, jerking motions. She may become unresponsive, stop breathing. And with every seizure, her brain is at risk for damage, putting her further and further behind developmentally.

For her parents, John and Jennifer, days are long, nights often sleepless. They know at any minute their daughter's life could be over.

Caring for a child with an illness like Dravet is a full-time job, said Dr. Addie Hunnicutt, a neurologist and Mackenzie's doctor.

And yet, if her parents have anything to say about it, Mackenzie's life will be joyful. It will be calm. It will matter.

John and Jennifer Boswell have never had easy lives. John Boswell has been in more car accidents than any 10 people gathered in a room, all but one not of his doing. He's torn up a knee, fractured his skull, broken his jaw. There aren't too many parts that haven't been repaired.

Mrs. Boswell was born with familia spastic paraplegia, a disease her father and sister also have, in which the muscles in the legs are too tight, causing problems walking. She's had multiple surgeries and still walks with a limp.

They met the night Boswell's best friend died. She had been dating the friend, who was hit by a car while walking to a store during a weekend at Lake Keowee. John and Jen bonded over their grief and then their relationship became much more.

Their first child, Kyle, was born in June 2011. He has the same muscle disease as his mother and will require surgery at some point, a third-generation Shriners' kid, his mother says. He toddles around the house quite nicely on his tiptoes and uses a walker for more extensive excursions.

They found out Jen was pregnant again on the day of John's mother's funeral. They decided to name the baby after her. Mackenzie Allison Kaye was born in September 2012, red hair, big blue eyes, nine pounds, 14 ounces. Perfect baby.

Two months later, John and Jen were in their Travelers Rest home, relaxing in recliners on either end of their couch. It had been a chilly day. They'd taken Mackenzie to the doctor for routine shots. Ill-tempered and running a bit of a fever, she'd been asleep but was now awake in Jen's arms.

They'd just finished dinner. At about 8 p.m., Mackenzie began convulsing. She stopped breathing several times. Jen, who trained as a nurse's assistant, knew her daughter was having a seizure. Calmly she told John, "Get her on her side. Get her to breathe."

Minutes passed. No ambulance. Forty minutes. Mackenzie was still seizing. They were getting in their car when EMS arrived and took her to Greenville Memorial, 30 minutes away. By the time they got to the hospital she was lethargic but asleep.

Blood work. Tests. Perhaps it was an immune deficiency, a sodium deficiency. Medication. More seizures — so many the hair on the back of her head rubbed off from the convulsions that jerked her head against the floor, the bed, the couch.

She endured painful injections of medication drilled right into the bone in her leg to end seizures.

Hospital stays, overnight and longer, but rarely did she have a seizure in the hospital. Jen recorded some on her phone to show the doctors what was happening.

More tests. Always tests. Seizures at least twice a day, sometimes three.

Last May, the Boswells took their daughter to the Medical University of South Carolina. Doctors there had all the results, the screens, the extensive work from Hunnicutt.

John and Jen waited in an exam room. Then the doctor came in and told them, "I think she has Dravet. We can confirm in two weeks with genetic testing."

Devastated and too stunned to ask all the questions they had, the Boswells gathered their daughter and her things and went to their car and cried. Then they drove to the beach. It was cold and rainy, but Mackenzie loves the water. She wanted to rush off into the surf. Then they drove back to Travelers Rest.

Jen started researching. Very poor prognosis, she read. She found a Facebook page with pictures of Dravet children, and few were older than 10. Children go to sleep and the brain stops. It was overwhelming.

As promised, two weeks later, the phone call came. The diagnosis was confirmed. A rare disease, a relatively newly found disease, had become their life partner.

Jen Boswell seems the kind of woman who, if she wasn't in nursing, would be a salesperson in a high-pressure company. She's one of those people who, when told no, simply says, I haven't explained it properly.

From the outset, her goal was to give her daughter a happy life. As normal as possible. Jen and John drew closer as challenges and pain mounted, rather than pulling apart. To be sure, there are days when they cry all day. Sometimes they get mad. They've been known to squirt mustard and ketchup at each other. Once they threw mushy oranges. Another time Jen slung everything on the counter onto the floor.

"You feel better now?" John said. And they both burst out laughing.

Their five-room house is not the tidiest and won't be in Architectural Digest, but it's clean and they are making it on disability checks, food pantries and money Jen makes caring for a friend's child. John worked at Lowe's on Woodruff Road until he had to have ankle surgery. He has a disability hearing in June.

"The kids get what they need, and John and I do without," Jen said. She smiled as she spoke. She's not one to feel sorry for herself.

"What good would it do?" she said.

Therapists make the trek to the house in the northern reaches of Greenville County weekly. An interventionist, occupational therapist, physical therapist, speech therapist. Tests show Mackenzie is developmentally about 9 months old, Hunnicutt said. She can say five or six words, most recently learning to hold up two fingers and say "two." A child her age should have a vocabulary of 20 to 50 words, Hunnicutt said.

She crawls rather than walks. On a recent day, she zoomed across the room as the interventionist engaged her in first one toy, then another. A year ago she could hardly roll over. She could barely grasp a finger.

Now she packs a mean punch. John calls her the Sour Patch Kid for her mood changes. Loving to irritable in 60 seconds. The doctor the family sees at MUSC wants to test for autism. Hunnicutt said she's not ready to make that diagnosis.

Mackenzie takes three medicines a day and has trouble eating. Hunnicutt believes rather than a physical problem, it has more to do with texture. Mackenzie gets her nutrition from milk and Ovaltine and the food Jen manages to force-feed her.

"That girl can eat some cereal," Jen said.

Addie Hunnicutt attended the University of South Carolina Medical School, completed a residency at Greenville Hospital System, a fellowship in pediatrics at Duke University Medical Center and specializes in pediatric neurology with expertise in pediatric epilepsy. She's one of four doctors in Children's Hospital Neurology with the Greenville Health System.

In the practice, which serves communities within a 150-mile radius of Greenville, there are five children with Dravet. Studies show fewer than one in 40,000 children have the disease, which in Mackenzie's case is caused by a genetic mutation. One in 1,000 will die, often while sleeping.

The syndrome was described in medical literature for the first time in 1978 by Charlotte Dravet, a French psychiatrist who works in Italy. Her work has become a model for studying genetic childhood epilepsies.

Typically seizures begin before 6 months of age, with the worst seizures occurring between ages 2 and 4.

The brain runs on electricity, Hunnicutt said, allowing communication between brain cells to keep everything working properly. In a seizure, the electricity becomes a thunderstorm. The entire brain is misfiring.

Seizures are never completely under control, Hunnicutt said. Prolonged seizures are Mackenzie's greatest challenge. Often children with Dravet will suffer intellectual disability.

Hunnicutt said besides the constant fear and weariness of caring for a child like Mackenzie, parents also face a challenge of affording all the medical supplies and preventative measures the child needs. Medicaid pays for a lot, but the things that help prevent seizures often are not covered.

"There are a lot of kids in need," Hunnicutt said.

That's where Travelers Rest United Methodist Church has come in. The United Methodist churches in the Greenville area have begun an effort to partner with families in poverty. A member at Travelers Rest told the church leadership about the Boswells.

In recent months, the church has bought them a cooling vest and a temperature monitor. Mackenzie has an oxygen machine the size of a carpet cleaner and a pad for her mattress that can sense when a seizure is occurring.

Last week the church had a fundraiser for the family. They need a bigger car, one in which the air conditioning works, or tinted windows for their Jetta.

The Rev. Jonathan Tompkins, pastor of the church, said members take a holistic approach to incorporate the family into the church fellowship.

"It's not just helping financially and medically, but spiritually and emotionally as well," he said.

One of the more controversial treatments is medical marijuana, which some families of epileptic children say stops the seizures altogether. Hunnicutt said she knows of a family who moved to Colorado so their child could use it. The Boswells would like for Mackenzie to have the chance to see if it would help. In South Carolina, as in most states, it is illegal.

Hunnicutt said no research has taken place to determine if marijuana can prevent seizures.

"I wouldn't encourage parents that it will be a cure all," she said, "It has to prove its worth."

Another course of action for children with Dravet is a special high-fat diet known as the Ketogenic diet. It requires special training for nutritionists, which none of those employed by Greenville Health Systems has. Hunnicutt said they are interviewing people for that position. The diet is mostly butter and mayonnaise and is usually administered through a feeding tube, she said. The measurements must be precise.

The founder of the Dravet Syndrome Foundation, Lori O'Driscoll, believes the diet has saved her daughter's life and enabled her to progress developmentally. Ciara was diagnosed at 5 months after she suffered a seizure in a grocery store six months earlier. She is now 8 and reading and writing on grade level.

The foundation was established in 2009 and through several fundraisers a year has awarded $1.6million in research grants. O'Driscoll is committed to finding a cure.

For now, Mackenzie has a mechanism implanted in her chest that, when swiped with a magnet, is designed to stop a seizure. It worked once so far. And once it didn't, but Jen thinks that's because the magnet was not fully charged. That seizure, last week, sent her to the hospital overnight.

Mackenzie is down to one to two seizures a week. The medications that Hunnicutt prescribed seem to be working.

One day, one week, at a time.

"All we have is time," Jen said. "She's not an obligation to us. She's our child. We do it because we love her, not because we have to."

Mackenzie is awake now, scooting from one toy to the next, roaming the living room. She skitters over to a visitor and pulls up to a standing position. It's obvious she wants to walk. She takes a step and, plop, she's sitting down.

Kyle and his friend are playing with Hot Wheels, dozens of them, on the couch, not paying attention to the little sister. But they know, too, what to do should a seizure develop. Stay out of the way.

Kyle, though, feels the same terror as his parents. He knows she might have to go to the hospital. She might not come back.

Her parents, close by, are waiting for nightfall, when the temperature drops and the heat no longer threatens her. For the first time of the day it is safer — not ever safe — to let her go outside.