Pediatric autoimmune neuropsychiatric syndrome (PANS) is a term used to describe a clinical picture which includes sudden onset of psychiatric symptoms and a possible autoimmune genesis. The sudden decline in neuropsychiatric functioning as well as the multiple combinations of symptoms may lead to a clinical phenotype similar to that in infantile autism (IA) with regressive features. We are conducting a study with the aim to evaluate a diagnostic test for PANS currently marketed by Moleculera Labs. All patients in Sweden who had taken the test (n = 154) were invited to the study.

The aim of the study is to characterize a subgroup of patients with IA within the PANS diagnosis study.

Participants (n = 53) were examined for psychiatric and somatic symptoms and evaluated for PANS caseness by an experienced psychiatrist. Because the criteria for entering the study was having taken the diagnostic test for PANS, the participants in the study comprise a group with mixed symptoms.

Twelve participants had IA. Eleven of these reported a developmental regression with loss of abilities. Two of the IA patients also fulfill criteria for PANS. Eight of the IA patients had been treated with antibiotics for psychiatric symptoms and 4 reported a positive effect of this treatment. Nine of the patients had elevated test results suggesting possible PANS according to Moleculera Labs.

Very early onset on PANS may be phenotypically similar to IA with regressive features. Further analysis of the immunological attributes of patients with autism with regressive features is warranted.

The authors have not supplied their declaration of competing interest.