On 15th April 2022, the WHO issued a report on temporally clustered cases of severe acute hepatitis of unknown cause in children, predominantly under 5 years of age, in the UK.1 2 Clinicians were urged to identify and report probable cases, defined as anyone 16 years or younger presenting with acute hepatitis (with serum aspartate or alanine transaminase greater than 500 IU/L) since 1 October 2021.3 The gene discussed is GPT; the disease is Acute hepatitis.