True about fibronectin nephropathy are all except:: (A) Autosomal recessive inheritance, (B) Glomerular enlargement with PAS+ trichrome+ mesangial deposit, (C) Glomerulus do not consistently stain for Ig and complement, (D) Ultrastructural feature is presence of large electron dense mesangialorsubendothelial deposit
Answer is A. Ans. (a) Autosomal recessive inheritance(Ref: Rosai 10th/pg 1153)Fibronectin glomerulopathyDefinitionCharacterized by massive fibronectin deposition in the glomeruli.Genetic basisCaused by mutations of FN1 gene on chromosome 2q34InheritanceHereditary autosomal dominant (option A) disease; Both sexes are equally affectedClinical featuresProteinuria (nephrotic range), microscopic hematuria & slow deterioration of renal function over a period of several years.Light microscopy* Glomeruli appear enlarged & lobulated with minimal degree of hypercellularity* Most characteristic feature: marked enlargement of mesangium & subendothelial (option D) space due to deposition of a homogeneous PAS +ve, Congo red -ve (option B) materialElectron microscopyDense granular appearance of the deposit in mesangium or subendotheliumImmunohisto-chemical studies* Strong positivity for fibronectin in the areas corresponding to the deposits.* Scanty immunoglobulins & complement factors may occasionally be seen, inconsistently. (option C)PrognosisPoor prognosisRecurrence after renal transplantThe disease has been reported to recur after renal transplantation.