New research suggests that as a many as a quarter of cerebral palsy cases are related to an underlying genetic condition.

Researchers sequenced the DNA of 50 children and adults with various types of cerebral palsy. About half had no known risk factors for the condition while the remainder were either individuals with a risk factor like prematurity, a brain bleed or oxygen deprivation or those considered to be “CP masqueraders” meaning that they exhibited most symptoms of cerebral palsy but had seen their condition deteriorate over time, which isn’t typical.

In 26% of cases, the sequencing uncovered a genetic variant that is either known to cause or likely to cause the developmental disability, according to findings published recently in the Annals of Clinical and Translational Neurology.

The odds of finding a genetic cause were greatest among the “CP masqueraders,” but a culprit was also identified in 29% of cases where there was no known risk factor and even in 15% of those with a known risk factor for cerebral palsy.

“In cerebral palsy, the first thing that comes to many physicians’ minds is birth injury or asphyxia,” said Dr. Siddharth Srivastava, a neurologist at Boston Children’s Hospital and a senior author of the study. “That idea has become pervasive, in both neurology and orthopedics training and in the general public.”

Srivastava said that the research could offer relief for many families.

“One mother of an adult child with CP told us that his genetic diagnosis absolved her of more than three decades of guilt,” Srivastava said. “Many families felt they finally had a sense of closure.”

What’s more, the researchers said that understanding the genetics at play actually altered the care plan for some of the people in the study. An adolescent who had always been thought to have cerebral palsy found out that he had a mutation associated with a progressive neurological disorder and needed to be looking out for changes in his condition, for example. And an adult was referred to ocular and kidney specialists based on results from the sequencing.

“This work is groundbreaking and very exciting,” said Dr. Benjamin Shore, co-director of the Cerebral Palsy and Spasticity Center at Boston Children’s Hospital and a researcher on the study. “Historically, the diagnosis of CP has been assigned to many children who have elements of muscle tightness and developmental delay without really understanding the cause. We can now investigate these causes with much more detail. I hope in the future we can provide genetic diagnoses for many more children, particularly CP masqueraders.”

Researchers said the findings highlight the importance of regularly re-evaluating kids with cerebral palsy to ensure that nothing is being missed or changing over time.