<prompt> 65 year old man presents with anaemia and posterior column dysfunction, the likely cause is:B1-deficitB12-deficitSSPEMultiple sclerosis  <response>: Ans. is b Vit. B12 deficit Ref Harrison, 16e, p 2458 15e, p 2432.Patient with anaemia and post, column dysfunction is most likely suffering from subacute combined degeneration of the cord. SACDSACD occurs due to vitamin B12 deficiency.Vitamin B12 deficiency leads to megaloblastic anaemia and defects in myelination. Demyelination occurs in predominantly post-column and pyramidal tract and later in the course peripheral nerves are also involved. 