Azathioprine-Induced Severe Myelosuppression Accompanied by Massive Hair Loss and Painful Oral Ulcer in an Autoimmune Hepatitis Patient with NUDT15 Minor Variant: A Case Report

A 65-year-old woman with autoimmune hepatitis experienced severe myelosuppression, massive hair loss, and painful oral ulcers after starting azathioprine treatment. Genetic testing revealed a homozygous variant of the NUDT15 gene, which predicts azathioprine toxicity. The adverse reactions required hospitalization, discontinuation of azathioprine, and treatment with granulocyte colony-stimulating factor and antibiotics. This case underscored the importance of early recognition of symptoms and genetic testing for NUDT15 variants to prevent severe side effects in patients undergoing thiopurine therapy.