**3. Pellagra summary**

Pellagra was a systems failure causing premature ageing and widespread neurodegeneration or dysfunction with evidence of mitochondrial failure, oxidative stress and proteinopathy. Poor intellectual development and dementia were key features as were many neuropsychiatric effects and poor social behaviour. Severe forms resembled Jacob-Creutzfeld disease (still misdiagnosed at times), with myoclonic encephalopathy and common biochemical features with NAD disturbances [19]. Gut infections and a high incidence of TB were major features. There were many undiagnosed and untreated cases as the exaggerated sunburn rash (Casal's necklace) was often not present or as noticeable ("pellagra sine pellagra") particularly in those with pigmented skin.
