<prompt> A 53 year old male, consumes alcohol in heavy dose for a long time, with documented evidence of vitamin B 6 deficiency, presented with pigmented rash of sun-exposed areas, bright red tongue, diarrhea, apathy, memory loss and disorientation. What could be the cause for these features?Niacin deficiencyRiboflavin deficiencyFolate deficiencyThiamine deficiency  <response>: The clinical features are suggestive of niacin deficiency. Alcoholism, vitamin B6 deficiency, riboflavin deficiency and tryptophan deficiency are the contributing factors for niacin deficiency. Ref:Harrisons Principles of Internal Medicine, 18th Edition, Page 594 