The present invention relates to protein kinase A (PKA) for use in diagnosing autism spectrum disorder (ASD) phenotype 1 in an ASD patient wherein PKA levels are measured in a sample of the patient and wherein ASD phenotype 1 is diagnosed if the measured levels are lower than PKA levels in an age and sex-matched control sample. Additionally, the present invention relates to PKA for use in monitoring variation in ASD severity in an ASD patient, wherein PKA levels are measured in a sample of the patient and an increase in ASD severity is characterized by a decrease of PKA levels compared to PKA levels measured in previous samples of the patient. The present invention also relates to PKA for use in monitoring efficacy of an ASD treatment in an ASD phenotype 1 patient, wherein PKA levels are measured in a sample of the patient and wherein a positive response to the ASD treatment is characterized by an increase of PKA levels in comparison to baseline PKA levels of the patient prior to treatment. Furthermore, the present invention is directed to methods of diagnosing ASD phenotype 1 as well as kits comprising means to measure PKA levels.
BIOMARKER ASSAY FOR USE IN MONITORING AUTISM