Ans. is 'd' i.e., Hypopigmentation* Maple syrup urine disease is caused by a defect of branched chain keto acid dehydrogenase (BCKADH), the enzyme which is involved in the catabolism of branched chain amino acids - valine, leucine and isoleucine* The disorder is so called because of the classic sweet odour observed in urine. This classic odour is found to be because of the presence of sotolone (a metabolite of branched chain keto acids) in urine* The enzyme BCKADH has three subunits - Branched chain keto acid dehydrogenase, Dihydrolipoyl transacetylase, Dihydrolipoyl dehydrogenase. It uses 5 coenzymes - thiamine pyrophosphate,, lipoamide, CoA, FAD and NAD* Mutation of any of the genes of any of the subunits involved in the complex can result in maple syrup urine disease.* It presents as either an early onset acute illness or as late onset chronic disorder.* Early onset acute illness# The infant is normal at birth but slowly neurodegenerative features are observed and it progresses rapidly and the infant dies close to 6 months* Late onset chronic illness# In late onset type, the person is normal and features appear during metabolic crisis states like during starvation or catabolic states. As during starvation or during catabolic states, the person presents with# Weight loss# Hypoglycemia# Ketoacidosis# Diorrhea, vomiting, dehydration# Neurological manifestations like alternating hypotonia and hypertonia, ataxia, seizures, coma# Pancreatitis* Diagnosis can be done using dried blood spot analysed using HPLC and Tandem mass spectrometry* Screening tests includes DNPH test (Dinitrophenylhydrazine test). DNPH reacts with the carbonyl groups of aldehydes and ketone to give a red or yellow complex.* Treatment involves diet (restriction of valine, leucine and isoleucine with formula foods) and supplementation of vitamins, minerals and omega 3 fatty acid)* To avoid RBCs of the sample utilising glucose of the plasma, fluride is added in the tube (Grey topped tube). Fluride inhibits glycolysis in RBCs. Hence it avoids false low values of glucose.* Pyruvate dehydrogenase is an enzyme complex made up of three subunits - pyruvate dehydrogenase, dihydrolipoyl transacetylase. Dihydrolipoyl dehydrogenase. Lipoamide is one of the coenzymes required for this enzyme complex. During the process of conversion of pyruvate to acetyl CoA, lipoamide gets reduced to form dihydrolipoamide. Regeneration of lipoamide is not possible in the presence of arsenite