Methylphenidate in KBG Syndrome: N-of-1 Series

Who May Qualify: - Age 6-20 years - Molecularly confirmed diagnosis of KBG syndrome (pathogenic ANKRD11 variant or a chromosome 16q24 deletion including ANKRD11) - Attention deficit or ADHD-related symptoms or a formal ADHD diagnosis, with a significant impact on daily life\* - Presence of a subject's caregiver or supervisor for proxy-reports Who Should NOT Join This Trial: - Family history of acute cardiac death that warrants further cardiac investigation - Cardiovascular disease in medical history (severe hypertension, heart failure, arterial occlusive disease, potentially life-threatening arrythmias, angina pectoris, hemodynamically significant congenital heart defect, cardiomyopathy, myocardial infarction and channelopathy) - Current or previous presence of hyperthyroidism, glaucoma or pheochromocytoma - Use of (psychotropic/stimulant) drugs which interact with MPH - Schizophrenic or psychotic disorder in medical history - Unstable epilepsy (not controlled with medication) - History of frequent drug and/or alcohol abuse - Excessive alcohol/drug use and/or intoxication with one or both during the study - Pregnant or lactating women - Inability to understand or speak Dutch Always talk to your doctor about whether this trial is right for you.