Ans. (a) Pellagra like symptomsRef: Harrisons 20th ed. P 3021Hartnup Disease* It is an AR condition, mainly seen due to defect in the transport of tryptophan and other neutral amino acids from the renal tubules and intestine* Molecular defect: SLC6A19 gene (encode transporter protein of these amino acid)Clinical Features:* MC: Cutaneous photosensitivity* Constant neutral aminoaciduria* Intermittent pellagra like symptoms* Intermittent ataxia (unsteady wide based gait)Diagnosis: Obermeyer test (urinary test for indole compound)Treatment: High protein diet and Nicotinic acid Extra Mile* Drummond syndrome/Blue diaper syndrome: Tryptophan transport defect lies only in intestine, NOT in kidneyClass of substance and disorderIndividual substratesTissues manifesting transport defectMolecular defectMajor clinical manifestationsInheritanceAmino acids CystinuriaCystine, lysine, arginine, ornithineProximal renal tubule, jejunal mucosaShared dibasic-cystine transporter SLC3A1, SLC7A9Cystine nephrolithiasisARLysinuric protein intoleranceLysine arginine, ornithineProximal renal tubule, jejunal mucosaDibasic transporter SLC7A7Protein intolerance, hyperammonemia, intellectual disabilityARHartnup diseaseNeutral amino acidsProximal renal tubule, jejunal mucosaNeutral amino acid transporter SLC6A19Constant neutral aminoaciduria, intermittent symptoms of pellagraARBrain branched- chain amino acid deficiencyLeucine, isoleucine, valinePlasma membrane of blood brain barrierBranched-chain amino acid transporter SLC7A5Microcephaly, intellectual disability, seizuresARCitrullinemia type 2Aspartate, glutamate, malateInner mitochondrial membraneMitochondrial aspartate/glutamate carrier 2 SLC25413Sudden behavioral changes with stupor, coma, hyperammonemiaAR