Pellagra

This is caused by a deficiency of vitamin B3 (niacin) and tryptophan. 

Physiology

Niacin and nicotinamide are both precursors of the coenzymes NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate).

Vitamin B3, is synthesized from tryptophan via kynurenine and quinolinic acids.