Ans. is 'a' i.e. Beta 2 microglobulin Dialysis-related amyloidosis (DRA) is a disorder caused by tissue deposition of beta2 microglobulin as amyloid fibrils.The clearance of beta2 microglobulin, a component of the major histocompatibility complex that is present on cell surfaces, normally occurs by glomerular filtration with subsequent reabsorption and catabolism in proximal tubules. Clearance therefore declines in patients with reduced kidney function, leading to plasma accumulation and slow tissue deposition.The tissue deposition of amyloid detected histologically occurs much earlier than any clinical or radiographic manifestations of the illness.In contrast to fragments of immunoglobulin light chains in primary amyloidosis and serum amyloid A in secondary amyloidosis, the amyloid protein in DRA is composed primarily of beta2- microglobulin.The amyloid found in the bone cysts and synovial tissue in patients with DRA is similar to other forms of amyloid in its staining properties with Congo red and in exhibiting apple-green birefringence under polarized light. It has been proposed that beta2- microglobulin has a high affinity for collagen, an effect that could explain the predominance of joint and bone diseaseClearance of beta2-microslobulinUnderlying the tissue deposition of beta2-microglobulin among patients with end-stage renal disease is the inability to adequately clear this substance, even with modem high flux hemodialysis and/or convective therapies. Bones and diseasesLess tendency to deposit in gastrointestinal organsRarely involvesp2 amyloid has preference for deposition in bones joints and synoviump2 amyloid has affinity for collagenCarpal tunnel syndromeScapulohumeral periarthritisEffusive arthropathySpondyloarthropathyBone diseasesColonStomachEsophagusSmall intestineCardiacPulmonarycutaneousTissue histologyIn contrast to fragments of immunoglobulin light chains in primary amyloidosis and serum amyloid A in secondary amyloidosis, the amyloid protein in DRA is composed primary of beta2-microglobulinThe amyloid found in the bone cysts and synovial tissue is similar to other forms of amyloid in its staining properties with Congo red and in exhibiting apple-green birefringence under polarized light - Biopsy remains the "gold standard" for the diagnosis of beta2- microglobulin amyloidosis. Despite this, the diagnosis of DRA is usually clinical and relies upon the combination of typical clinical features plus characteristic radiographic findings. Abdominal fat pad aspirates are not useful for the diagnosis of DRA.Type of AmyloidosisMajor Fibril proteinPrecursor proteinSystemic Amyloidosis Primary amyloidosisSecondary amyloidosisHemodialysis associated amyloidosisALAAAb2 microglobulinImmunoglobulin light chainSSAb2 microglobulinHereditary amyloidosis Familial Mediterranean feverFamilial amyloidotic neuropathiesSystemic senile amyloidosisAAATTRATTRSAATransthyretinTransthyretinLocalized amyloidosis Senile cerebral(Alzheimer's)Medullary ca thyroidIslet of LangerhansIsolated atrial amyloidosisAbAcalAIAPPAANIAPPCalcitoninIslet amyloid peptideAtrial natriuretic factor