According to their findings, children experienced muscle-related symptoms around the age of four, while the majority of ALS patients are diagnosed in their 50s or 60s. The condition was linked to mutations in the SPTLC1 gene, which the researchers explained is related to the body’s fat production.
“ALS is a paralyzing and often fatal disease that usually affects middle aged people,” said Dr. Carsten Bönnemann. “We found that a genetic form of the disease can also threaten children. Our results show for the first time that ALS can be caused by changes in the way the body metabolizes lipids.
“We hope these results will help doctors recognize this new form of ALS and lead to the development of treatments that will improve the lives of these children and young adults. We also hope that our results may provide new clues to understanding and treating other forms of the disease.”
Understanding a new form of ALS
For the study, Dr. Bönnemann and his group analyzed medical records for 11 patients who showed signs of ALS from as young as four years old. However, unlike adults with ALS, the children’s symptoms were more severe for longer periods of time.
“These young patients had many of the upper and lower motor neuron problems that are indicative of ALS,” said researcher Dr. Payam Mohassel. “What made these cases unique was the early age of onset and the slower progression of symptoms. This made us wonder what was underlying this distinct form of ALS.”
After analyzing the DNA make-up of each of the patients, the researchers identified a key difference in the children with ALS -- changes to the SPTLC1 protein. While some of the children were born with a genetic mutation that created this change, others had it passed down from their families.
With more blood tests, the researchers learned that the SPTLC1 protein was responsible for the overproduction of sphingolipids, which is a fatty acid found in brain tissue. They explained that the SPTLC1 protein is related to an enzyme known as SPT; in the ALS patients, there was no regulation of the SPT enzyme, which is what led to an abundance of sphingolipids in the body.
“Our results suggest that these ALS patients are essentially living without a brake on SPT activity,” said Dr. Dunn. “SPT is controlled by a feedback loop. When sphingolipids are high then ORMDL proteins bind to and slow down SPT. The mutations these patients carry essentially short circuit this feedback loop. We thought that restoring this brake may be a good strategy for treating this type of ALS.”
Moving forward, the team hopes to create treatment options for children struggling with ALS. By silencing the SPT enzyme, the researchers hope that they can better regulate the level of sphingolipids to help keep symptoms at bay.