The present invention provides specific 4-(p-quinonyl)-2-hydroxybutanamide derivative compounds, pharmaceutical compositions comprising them, and those compounds and compositions for use methods of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, and treating a subject suffering from a pervasive developmental disorder selected from the group consisting of Autistic Disorder, Asperger's Disorder, Childhood Disintegrative Disorder (CDD), Rett's Disorder, and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS).