Sanfilippo Syndrome Is Basically Childhood Alzheimer's—Here's What That Means
When mother-of-two Sarah Stewart started noticing that her 2-year-old daughter, Mary Mitchell Stewart, wasn't speaking as well as other kids her age, she wondered if her little girl might be on the autism spectrum. The true diagnosis, however, was something much more grave.
Mary Mitchell was diagnosed with Sanfilippo syndrome, a rare genetic condition dubbed “childhood Alzheimer’s." This progressive neurodegenerative disorder, which affects approximately one in every 70,000 children, causes a loss of speech and comprehension. Eventually, a child who has it will become completely immobile.
Kids with Sanfilippo syndrome typically don't live past their teens. Unfortunately, there is currently no cure.
“We were shocked,” Stewart said in an interview with Today. “We were in disbelief to be told it was something that effects her life expectancy and to be told on top of that there was no treatment.”
Mary Mitchell's initial symptoms were subtle. Her lack of speech was the most noticeable, Stewart told Today, but she also wasn't able to draw the way children in her class could. Mary Mitchell could only draw a circle, while the other kids were able to draw a smiley face.
The family was devastated when Mary Mitchell, who is now 3, received her diagnosis. Fortunately, an experimental gene therapy Mary Mitchell recently underwent is giving her family hope.
Sanfilippo syndrome, also known as mucopolysaccharidosis type 3 (MPS3), occurs when the body is missing or doesn't have enough of certain enzymes needed to break down long chains of sugar molecules, Patricia Dickson, MD, chief of the division of genetics and genomic medicine at Washington University in St. Louis, Missouri, tells Health. Those sugar molecules then build up in the cells and cause progressive damage.
There are four known enzyme deficiencies that cause Sanfilippo syndrome, described as type A, B, C, or D. Mary Mitchell has type A, which is the most common type and strikes the youngest children.
Symptoms typically begin with behavioral problems, such as irritability or aggression, in the toddler years, Dr. Dickson says. As in Mary Mitchell's case, many parents mistake the symptoms for autism.
The biggest red flag, however, is if a child begins to lose the skills most kids acquire as toddlers, such as speech. Difficulty sleeping, coarse facial features, joint stiffness, and abdominal issues are also signs.
Sanfilippo syndrome is inherited in an autosomal recessive pattern, meaning both parents must carry the mutated gene. Parents typically don't display symptoms, however, and they likely would not know if they are carriers, Dr. Dickson explains.
The experimental therapy that is giving Mary Mitchell's family hope is a one-time treatment. Doctors at Weill Cornell Medical Center in New York City placed a properly functioning gene in Mary Mitchell's brain via surgery. The goal is for that gene to enter the body and begin making the enzyme that Mary Mitchell lacks.
Just a week after Mary Mitchell's surgery, her family said that they began seeing improvements. Her speech was much clearer, and she even used new words. Her family hopes that because they started Mary Mitchell's treatment so early, it will prevent her from declining.
Dr. Dickson says there is good reason to believe treatments like this one could be successful, though it's too early to say whether they will be for sure.
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