Blunting of the renal calyces refers to the blunting of the anterior and posterior flattened, funnel-shaped shape of the calyces due to some organic condition. Blunted renal calyces are one of the clinical manifestations of nail-patellar syndrome, as well as one of the complications of nail-patellar syndrome. Nail-patellar syndrome or hereditary bone-finger (toe) nail dystrophy is an inherited disorder characterized by patellar hypoplasia or absence, finger (toe) nail dystrophy, elbow dysplasia, iliac angle, and renal failure. it was first described by Little in 1897. in the mid-1960s Muth and Silverman described the syndrome’s glomerular Structural lesions in the late 1960s and early 1970s Hoyer and Bennett began a comprehensive study of the ultrastructure of the glomerular basement membrane and renal pathological features in this syndrome, proposing a modern theory of the structural basis of nail-patellar syndrome renal lesions and suggesting that the syndrome may be due to a biochemical defect in basement membrane collagen. The main manifestations of renal damage are proteinuria, microscopic hematuria edema and hypertension, occasionally nephrotic syndrome, with a relatively benign course, and only 10% of patients enter renal failure in late stages. Extra-renal manifestations include dystrophy of the nails, patellar agenesis on one or both sides, elbow deformities, angular pelvis and other skeletal abnormalities. Nail-patellar syndrome is most often noted for difficulty walking due to patellar agenesis and can be diagnosed on the basis of typical skeletal changes, with the presence of renal impairment being more likely to confirm the diagnosis. Radiological examination shows the iliac angle as a characteristic change, which has a clear diagnostic significance. A few patients with ultrastructural changes of the glomerular basement membrane without skeletal, skin, finger (toe) nail, and other typical manifestations of this syndrome have been reported, and these patients were considered to be the tonoplastic or single nephrotic variant of the syndrome. However, the electron micrographs published in these studies do not strongly support this view. Judgment of renal biopsy specimens cannot be made solely by the phenomenon of glomerular basement membrane moth-eating, but must be more valuable for diagnosis by identifying the protofibers with phosphotungstic acid staining due to its higher sensitivity.