<prompt> Expected change in Vitamin B,2 deficiencyIncreased homocysteine in urineIncreased methylmalonic acid in urineFIGLU in urinePhenylalanine in urine  <response>: Ans. is b i.e., Increased methylmalonic acid in urine Isomerization of methvlmalonyl CoA to succinyl CoAIn this reaction, active form of vitamin BI2 is deoxyadenosyl cobalamine.Propionyl-CoA is produced as catabolic end product of some alipathic amino acids andb-oxidation of odd chain fatty acids.Propionyl CoA is then conveed to succinyl CoA through methylmalonyl-CoA.Thus methylmalonyl-CoA is accumulated and excreted in urine as methylmalonic acid methylmalonate in vitamin B12 deficiency, i.e. methylmalonic aciduria. 