<prompt> Pellagra is caused by deficiency of:ThiamineNiacinBiotinAscorbic acid  <response>: Ans. b NiacinRef: K. Park 23rd ed. 619 Pellagra is caused by deficiency of Vitamin B3 Niacin. It is seen commonly in maize eating populations because maize is deficient in tryptophan which is usually converted to niacin. Therefore maize eaters develop deficiency of Niacin which ultimately leads to pellagra. 4 Ds associated to Pellagra: Diarrhea Dermatitis Dememntia Death In severe cases of pellagra Casals Necklace is seen which is a scaly pigmented rash around neck, seems like necklace. 