<s>[INST] context: Collapsing fRel Internet reference Robbin's 7th/e p 985] Focal segmental glornerulosclerosis:- The individual component of the name refers to the appearance of the kidney tissue on biopsy. Focal --> Only some of the glomeruli are involved Segmental --> Only pa of an entire glomerulus is involved Glomerulosclerosis --> Refers to scarring of the glomerulus Depending on the cause it is broadly classified as:? Primary When no underlying cause is found; usually presents as nephrotic syndrome. Secondary When an underlying cause is identified, usually presents with kidney. failure and proteinuria This is actually a heterogenous group including numerous causes such as:? - Infections such as HIV (HIV associated nephropathy) - Toxins and drugs such as he ruins predominate - Familial .forms - Secondary to nephron loss and hyperfiltration such as with chronic pyelonephritis and reflux, morbid obesity, diabetes mellitus Pathological variants Five mutually exclusive variants of focal segmental glomerulosclerosis may be distinguished by the pathological findings seen on renal biopsy:? Collapsing variant Glomerular tip lesion variant Cellular variant Perihilar variant Not otherwise specified variant (NOS) The NOS variant is the most common subtype. Recognition of these variants has prognostic value in individual with primary focal segmental glomerulosclerosis. The collapsing variant is associated with higher rate of progression to end stage renal disease whereas Glomerular tip lesion variant has low rate of progression to end stage renal disease in most patients. Cellular variant shows similar clinical presentation to collapsing and glomerular tip variant but has intermediate outcomes between these two variants. The prognostic significance of perihilar and NOS variants has not yet been determined. Also know Genetic basis of focal segmental glomerulosclerosis Defect in the gene ACTN4 which encodes alpha actinis 4. A second gene associated with FSGS is TRPC6. [/INST] question: Which type of FSGS has worst prognosis ? | options: A: Tip variant B: Collapsing C: NOS D: Perihilar | answer: B </s>