First diagnostic criteria for Christianson syndrome

A new study provides the most definitive characterization of the autism-like intellectual disability disorder Christianson syndrome and provides the first diagnostic criteria to help doctors and families identify and understand the condition. Initial evidence suggests CS could affect tens of thousands of boys worldwide.

Because the severe autism-like condition Christianson syndrome was first reported only in 1999 and some symptoms take more than a decade to appear, families and doctors urgently need fundamental information about it. A new study that doubles the number of cases now documented in the scientific literature provides the most definitive characterization of CS to date. The authors of the study propose the first diagnostic criteria for the condition.

"We're hoping that clinicians will use these criteria and that there will be more awareness among clinicians and the community about Christianson syndrome," said Dr. Eric Morrow, assistant professor of biology and psychiatry and human behavior at Brown University and senior author of the study in press in Annals of Neurology. "We're also hoping this study will impart an opportunity for families to predict what to expect for their child and what's a part of the syndrome."

In conducting their study, which includes detailed behavioral, medical, and genetic observations of 14 boys with CS from 12 families, the team of scientists and physicians worked closely with families of the small but fast-growing Christianson Syndrome Association and hosted the group's inaugural conference at Brown's Alpert Medical School last summer.

In the study, Morrow's team was able to quantify the most frequent symptoms specific to CS. These include moderate to severe intellectual disability, epilepsy, inability to walk and talk or difficulty doing so, attenuated head and brain growth, and hyperactivity. Boys sometimes exhibit other specific symptoms including autism-like behaviors, low height and weight, acid reflux, and regressions in speech and motor skills after age 10 - that the researchers include as secondary proposed diagnostic criteria. A third of the boys also had potentially neurodegenerative problems such as atrophy of the cerebellum.

What's still not clear is whether the disease limits the eventual lifespan of patients.

Distinct genetic cause

Many CS traits, including a very happy disposition, appear similar to those of another autism-like condition, Angelman syndrome, but the study defines important differences.

Among the most important ones is that the two syndromes have distinct genetic underpinnings. In all CS cases, said Morrow, who treats autism patients at the E. P. Bradley Hospital in East Providence, boys have a mutation on the SLC9A6 gene on the X chromosome that disables production of a protein called NHE6 that is important for neurological development.

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