Investigators at the Clinic for Special Children in Strasburg, with help from a research institute in Phoenix, made their discovery after spending two years studying 10 Amish children here and elsewhere in Pennsylvania.

Their findings were reported in today’s issue of the New England Journal of Medicine.

“This is going to have significance outside the Amish population,” said Erik G. Puffenberger, laboratory director at the clinic.

“This will have a great deal of relevance for children in the general population with autism, seizures or mental retardation,” he said.

The researchers here and at the Translational Genomics Research Institute call the newly identified disorder “cortical dysplasia-focal epilepsy” syndrome, or CDFE.

Children with CDFE have a normal infancy, but begin getting frequent seizures — 50 to 90 per week — at 14 to 16 months of age, reported MedPage Today, an online medical news service.

The seizures are followed by a regression of language and the onset of hyperactivity, aggression, impulsive behaviors and mental retardation, said MedPage.

Dr. Kevin A. Strauss of the Clinic for Special Children said this collection of symptoms has appeared in the Amish population for generations, but previously had gone unnamed and its cause unknown.

The next step for researchers at the Phoenix institute will be to develop drugs to prevent the disorder by changing the way the brain responds to the mutated gene, said Dr. Dietrich Stephan, director of its neuro-genomic division.

Strauss, like Puffenberger and Stephan, said the findings could have broad implications outside the Amish community.

“This could be a ‘Rosetta Stone’ to what some other fruitful avenues of autism or epilepsy research can be,” said Strauss.

According to Puffenberger, the research began with a study of two siblings and two of their cousins among the “Belleville” Amish, who live in Mifflin and Juniata counties.

After isolating DNA from the four affected children and their six parents, researchers traced the disorder to a genetic mutation in a nervous-system protein named CASPR2.

Later the study group was expanded to a total of 10 children, including three from Lancaster County, all of whom showed the same symptoms.

In addition, 105 healthy Old Order Amish were studied as a control group. Four of this group were found to carry the recessive genetic mutation in the CASPR2.

Strauss and Puffenberger emphasized that the research not only led to the cause of the newly named disorder, but the discovery of the CASPR2’s role in healthy brain development.

Earlier research into the brain protein by other scientists who used cell cultures and mice did not suggest its role in either the seizures or brain development.

“It will be interesting to see if, in the general population, there are groups of children with seizures, mental retardation or autism — in combination or singularly — who have mutations in this gene,” said Puffenberger.

“We suspect there will be...If you took all the children in the United States with autism or seizures, a notable percentage — maybe 5 percent, maybe 10 percent — might have mutations in this gene. That’s what we expect. We don’t know that yet.”

But the findings have had an immediate impact, said Dr. Holmes Morton, co-founder of the Strasburg clinic, in a prepared statement.

“The identification of the mutation in CASPR2 in our Amish patients has already allowed us to recognize affected newborns before they become symptomatic.

“Our hope,” Morton continued, “is that early treatment and prevention of prolonged seizures in these infants will lessen the effects of the disorder upon the lives of children and their families.”

The Clinic for Special Children, established in 1989, is a nonprofit medical facility on Bunker Hill Road that serves Old Order Amish and Mennonite children who suffer from genetic disorders.

While providing pioneering clinical research, it also seeks to provide early diagnosis, affordable laboratory services and comprehensive medical and nutritional care for the children, as well as support for their parents.

The Translational Genomics Research Institute seeks to turn genomic discoveries into improved diagnosis and treatment of diseases. It opened in 2003.