Features apparently distinguishing PTP1B-related encephalopathy from AGS are a later age at onset (nine of 12 cases in our cohort presenting beyond 18 months of age), notable bulbar involvement manifesting as difficulties with swallowing and expressive speech, and cerebral atrophy as the predominant neuroradiological sign. The gene discussed is PTPN1; the disease is Aicardi-Goutieres syndrome.