This observational natural history study will follow individuals with MEHMO (Mental disability, Epileptic seizure, Hypopituitarism/Hypogenitalism, Microcephaly, Obesity) syndrome or an eIF2-pathway related disorder, who have symptoms such as intellectual delay, seizures, abnormal hormone and blood sugar levels, and decreased motor skills. No current treatment for these conditions is available. A major impediment to the testing of potential therapeutic interventions is the lack of well-defined outcome measures. This protocol seeks to identify biochemical and clinical markers to monitor disease progression, and better understand the natural history of these conditions. Any person diagnosed with MEHMO syndrome or related conditions, who can travel to the NIH Clinical Center can participate in this study. The study involves: * General health assessment and evaluation * Imaging studies * Laboratory tests * Collection of blood, urine, spinal fluid, skin biopsy.