In our report, given the fact that there was no previous psychiatric history, presenting encephalopathy, the rapid onset of the psychotic features, subclinical hypothyroidism, no other probable causes of encephalopathy in addition to the presence of anti-thyroid peroxidase antibody (TPOAb), high CSF proteins, and response to steroids made the diagnosis of HE as the most likely diagnosis. The gene discussed is TPO; the disease is Encephalopathy.