When Mary Mitchell Stewart wasn’t talking by age 2, her mom, Sarah Stewart suspected something was wrong. The Stewarts eventually learned that their toddler had Sanfilippo syndrome, also known as childhood Alzheimer’s, a rare genetic disorder that causes children to lose their ability to speak and understand before causing immobility and death by the time they are teens.
Almost at the same time as her diagnosis, they learned that there was a clinical trial for a gene therapy for Sanfilippo syndrome. They felt hopeful when Mary Mitchell became the second child to receive it and she started to thrive.
“We thought the gene therapy was doing its job and she continued to progress and was saying all kinds of new words, new phrases,” Stewart, 37, of Knoxville, Tennessee, told TODAY. “The number of words that I was adding started to slow down and there were no new words and then she started to plateau.”
But then Mary Mitchell, also known as Shug, stopped progressing and started deteriorating before passing away in October at age 5, younger than most children with Sanfilippo syndrome. The family has “absolutely no regrets” that they enrolled Mary Mitchell in the clinical trial.
“It was our one shot,” Stewart said. “I don’t think we thought it would be a cure. But we thought maybe it would slow the progression of the disease. You’re going to do whatever you can to help your child."
Lysogene, the company behind the therapy, issued a statement following Mary Mitchell’s death:
“The immediate cause of death is currently unknown and additional information is being collected. At this time, there is no evidence that the event is linked to the study drug administration … Lysogene is profoundly saddened by the passing of this child and extends its deepest sympathies to the family.”
Hope after treatment
Stewart spoke with TODAY a week after Mary Mitchell underwent the gene therapy in the spring of 2019. Almost immediately she and her husband, Mitch, noticed improvements. It was much easier to understand what Mary Mitchell said and she started using new words.
“It’s truly unbelievable,” Stewart told TODAY in May 2019. “We’re so excited and thankful.”
For months, Mary Mitchell improved and the family felt grateful. They loved seeing their “fiery” daughter enjoy life. The toddler, who loves Dolly Parton and would ask nurses to play “Jolene,” made an impression on everyone she met. In fact, she made such a mark that Parton even visited her and played her favorite song as Mary Mitchell watched enthralled. She was talking until about October 2019, but then she stopped.
“It was a year ago that Mitch (my husband) and I realized that not only did the gene therapy not work but also she was starting to regress at an unusually fast pace,” Stewart said. “We started the grieving process and accepting the fact that the progression of the disease was inevitable.”
Prior to last October, Mary Mitchell loved “Happy Birthday” and enjoyed singing it. When she started losing her ability to speak, the family started “doughnut Sunday” where they’d sing “Happy Birthday” with a candle in her favorite treat.
“Mary Mitchell has always loved doughnuts,” Stewart said. “Every Sunday we were going to show her how much she’s loved … That became our weekly tradition.”
They enjoyed their time together as much as they could. Yet, the last six months of her life were challenging for the family.
“It was like she was just this shell of a body that required all our time and attention,” Stewart said. “That was a very tough pill to swallow.”
But there were moments where they saw the spirited daughter they remembered. On her birthday on August 29, she woke with a stomach bug and the family worried she’d miss her drive-by parade but she was always a “fighter and she rallied.”
“We have the sweetest memories of her from her last birthday, her 5th birthday,” Stewart said. “For three hours so many people came by to see her. It was pretty incredible.”
Grappling with loss
Stewart and Mitch relied on their faith to keep them strong as they faced the death of their daughter at such a young age.
“We just see that as God's mercy on her because the disease is so ugly, so awful, so unimaginable,” she said. “We’ve just seen God show up so much it’s undeniable.”
They have received so much support and that helps, too.
“There’s just a countless number of people who have been affected by her story. It gives us so much hope and encouragement and knowing that Mary Mitchell's life, her short little life, her painful and broken little life, that there was purpose in it,” Stewart said.
While it’s been an incredibly difficult year for the family, including Mary Mitchell’s brother, Reynolds, the Stewarts believe they have grown from their tragedy.
“So much good has come from such a terrible diagnosis,” Stewart said. “I would have never chosen this road for my little girl, for Reynolds, for Mitch, for myself. But we said we couldn’t change it for the world because who we are today is different than who we were 20 months ago.”