Patellar syndrome

　　(I) Etiology

　　This syndrome is an autosomal dominant inheritance, with the gene locus linked to the adenylate cyclase and ABO blood type locus located on chromosome 9.

　　(II) Pathogenesis

　　Currently, little is known about the pathogenesis of this syndrome. Some believe it is a collagen disease, with abnormalities existing in the synthesis, assembly, or degradation of collagen. The cytological mechanism of this disease has not been studied. The lack of non-glomerular basement membrane damage in pathological changes suggests that various damages of this syndrome may originate from different mechanisms, and not all damages are related to basement membrane abnormalities. A few patients develop anti-glomerular basement membrane nephritis, supporting the hypothesis that the glomerular basement membrane components are abnormally arranged. The results of studies using monoclonal antibodies targeting the Goodpasture epitope found that 2/3 of patients' renal biopsy specimens did not bind to the monoclonal antibody, suggesting a certain degree of heterogeneity in the basement membrane components of this syndrome, and also suggesting the absence or alteration of Goodpasture antigen. It is worth noting that it is not clear whether this is an primary or secondary change in this syndrome.

　　In addition to its clinical manifestations, the nail-patella syndrome can also cause other diseases. This disease often complicates vesicoureteral reflux; renal calyces become blunt and renal calculi, iliac spine spurs, elbow and iliac varus deformities, etc., and occasionally, eye iris pigmentation abnormalities may occur.

　　1. Renal manifestations More than half of the nail-patella syndrome patients have no obvious renal clinical manifestations. Among patients with clinical renal manifestations, the characteristic manifestation is benign nephropathy, the most common symptom being varying degrees of proteinuria, microscopic hematuria and cast urine, edema, and hypertension. A study found that 56% of patients have abnormal precipitates in their urine, with impaired urine concentration ability, abnormal acidification, or protein secretion. 30% of kidney involvement may gradually develop into renal failure and die of uremia.

　　2. Skeletal and nail (toenail) damage The nail abnormalities of this syndrome include discoloration, spoon-shaped nails, longitudinal ridges, nail loss or nutritional disorders, and triangular nail arc shadows. These manifestations are often symmetrical and occur in 80% to 90% of patients. Nails are more susceptible to damage than toenails, with the thumb being the most frequently affected. About 60% of patients have patella absence or maldevelopment. These changes may be related to the lateral reduction during joint flexion, leading to genu varum deformity. Abnormal patella may also lead to osteoarthritis, osteoarthrosis, and joint effusion. 80% of patients with this syndrome have an iliac spine expansion, protruding forward and upward, known as the iliac angle. Abnormalities of the elbow include maldevelopment, distal humerus posterior prominence, causing increased carrying angle and restricted extension and supination function. Some patients are accompanied by radial head maldevelopment and radial-ulnar joint abnormalities.

　　Among the manifestations, the absence or incomplete development of nails (toenails), unilateral or bilateral patella absence or maldevelopment, iliac spine spurs, elbow and hip joint varus deformities, and other conditions are known as the nail-bone tetrad.

　　3. Other In addition to glomerular basement membrane defects, other structural abnormalities of the kidney and urinary tract in this syndrome have been found through radiological examination, including: renal pelvis dilatation and cortical scarring, suggesting vesicoureteral reflux; unilateral renal atrophy combined with double ureters and double renal pelvis; unilateral renal hypoplasia and contralateral double kidneys; renal pelvis blunting and renal calculi.

　　The main diagnostic basis of this disease is family history, and the typical clinical manifestations are X-ray signs of the skeleton and proteinuria. Renal biopsy may be performed if necessary.

　　Clinically, it is more common in adolescents, and the main manifestations of renal damage are proteinuria, microscopic hematuria, edema, and hypertension. Nephrotic syndrome is occasionally seen, and nephritis shows chronic progression, with an average age of about 30 entering renal failure. Extra-renal manifestations include nail dystrophy, unilateral or bilateral patellar agenesis, elbow joint deformity, angular pelvis, and other skeletal abnormalities. Most of the disease is noticed due to difficulty in walking caused by patellar agenesis. Diagnosis can be made mainly based on typical skeletal changes, and diagnosis can be made more reliably if renal damage is present. Radiological examination shows the iliac angle as a characteristic change, which has clear diagnostic significance.

　　There have been reports of a few patients with ultrastructural changes in the glomerular basement membrane without skeletal, skin, nail, and other typical manifestations of this syndrome. These patients are considered to be atypical or a single renal lesion variant of this syndrome. However, the electron microscopic photographs published in these studies do not strongly support this view.

　　The judgment of renal biopsy specimens cannot be made solely by the glomerular basement membrane phagocytosis phenomenon, but must be identified by phosphotungstic acid staining of the original fiber. Because it is more sensitive, it is more valuable for diagnosis.

　　The etiology of metatarsophalangeal syndrome is genetic. The gene causing metatarsophalangeal syndrome is dominant, meaning that there is a 50% chance of inheriting the disease gene for the next generation of patients with this disease. The majority of patients with metatarsophalangeal syndrome do not require treatment. If the patient develops renal failure, dialysis and kidney transplantation should be performed.

　　To prevent the onset of the disease in the next generation, patients who wish to have children should undergo genetic counseling.

　　Proteinuria, microscopic hematuria, and casturia may be present to varying degrees, with reduced urine concentration ability, acidification, or abnormal protein secretion. Thirty percent of patients with renal involvement may slowly progress to renal failure, and when renal failure occurs, uremic changes may be present.

　　1. Under light microscopy, the appearance of glomeruli shows considerable variability. In patients without renal functional damage, the glomeruli are usually normal or nearly normal. In some typical cases, partial capillary basement membrane thickening can be seen, but it is not普遍存在. Global or focal glomerulosclerosis can also be observed, which is related to the level of renal function damage, especially the degree of proteinuria, suggesting the role of proteinuria in the progression of renal damage in this syndrome. Other possible findings include increased epithelial and endothelial cells, crescent formation in association with anti-glomerular basement membrane disease, tubular atrophy and interstitial fibrosis that parallel the degree of renal function damage, intimal fibrosis, arteriolar hyalination, and so on. At this time, it often suggests the presence of hypertension.

　　2. Immunofluorescence examination Since this syndrome is not immune-mediated, the results of glomerular immunohistochemical examination are often negative. In cases of global or segmental glomerulosclerosis, irregular and focal deposits of IgM, C3, C1q, or all three can be observed. The deposits are distributed in the capillary wall or glomerular mesangium, or both, and their distribution is related to the stage and degree of glomerulosclerosis. When other pathological changes occur concurrently, immunofluorescence can show positive findings. In patients with concurrent anti-glomerular basement membrane disease, IgG and C3 can be seen as linear deposits in all glomerular capillaries, and the deposition of fibrin in the capillaries is a manifestation of crescent formation. The connection between this syndrome and anti-glomerular basement membrane disease is not clear, and it may refer to the persistent and severe damage to the glomerular basement membrane in patients with nail-patella syndrome, which changes the antigenicity of the glomerular basement membrane and leads to antibody production. Mackay et al. reported a case of nail-patella syndrome complicated with membranous glomerulonephritis, where uniform granular IgG deposits were observed in all capillary walls.

　　3. Ultrastructure Regardless of the appearance of the glomeruli under the light microscope in patients with this syndrome, and regardless of the presence of kidney symptoms such as proteinuria in clinical practice, the ultrastructure of the glomerular basement membrane in patients with this syndrome is always altered.

　　Common and characteristic damage is the abnormal ultrastructure of the glomerular basement membrane, where a large amount of translucent patchy material can be seen throughout the basement membrane. This material is sometimes also visible in the glomerular mesangial matrix, and it is called the characteristic 'maggot-like' manifestation. Standard lead citrate staining sometimes reveals coarse fibrils and cross-striated collagen in the glomerular basement membrane and mesangial matrix. Phosphotungstic acid staining shows these substances more commonly. The fibrils are in small clusters and located in the glomerular segmental basement membrane or distributed along the entire glomerular basement membrane. The thickness of the glomerular basement membrane is uneven, and the thickness variation range in the same capillary wall can range from normal to thickened. In the thickened parts of the glomerular basement membrane, the presence of the translucent band is more frequent and prominent. The glomerular mesangial matrix also increases, and in some cases, translucent substances and collagen fibers can be seen. The non-glomerular basement membrane of the kidney does not have translucent substances and collagen-like fibrils, and the changes in the renal tubular basement membrane show chronic tubulointerstitial nephritis-like damage, which is consistent with glomerular damage in the late stage.

　　In most cases, there is no electron-dense material deposition. The glomerular podocytes are often reduced or absent, and the degree of reduction is related to the severity of proteinuria.

　　A- Patellar syndrome dietary recipe

　　(1) Crucian carp and tofu soup

　　Ingredients: 1 crucian carp (about 250 grams), 400 grams of tofu

　　Preparation method:

　　Cut the tofu into 5 cm thick slices, blanch in salted boiling water for 5 minutes, then drain and set aside;

　　Scrape off the scales and remove the intestines of the crucian carp, rub with wine and salt, and soak for 10 minutes;

　　Place the pot on the stove, add cooking oil, and heat for 5 minutes. Add ginger slices and fry the fish until both sides are golden brown. Add an appropriate amount of water, bring to a boil over low heat for 30 minutes, add tofu slices, season, and sprinkle with chopped green onions.

　　(2) Chicken and Mushroom Soup

　　Ingredients: about 200g chicken, appropriate amount of mushrooms, scallions, ginger, preparation method

　　1. Cut the mushrooms into thin slices, blanch and remove for later use;

　　2. Cut the chicken into pieces and cook it in the pot until it boils, then add the mushrooms and cook together. After boiling, thicken with cornstarch and then remove from heat.

　　(3) Angelica and Ginger Mutton Soup

　　Ingredients: 20g ginger, 20g angelica, 100g mutton. Preparation: blanch the mutton with water, slice the ginger, wrap the angelica in gauze, and then simmer with the mutton.

　　(4) Enoki Mushroom and Egg Yolk Soup

　　Ingredients: enoki mushrooms, fresh mushrooms, two egg yolks

　　Accessories: nori, salt, ginger, scallions, chicken essence soup

　　Preparation method:

　　1. Wash the enoki mushrooms clean, cut off the roots.

　　After the shiitake mushrooms are soaked, make a crosshatch pattern. Cut the scallions into circles, and mince the ginger. Set aside the egg yolks for later use, and the egg whites can be added to other dishes for cooking.

　　2. Boil water in the pot, add egg yolks, enoki mushrooms, shiitake mushrooms, and then add chicken broth, season with ginger, salt, and chicken essence.

　　Simmer for 2 minutes.

　　3. Turn off the heat. Add scallions and nori

　　What foods are good for the body in metapателличный syndrome?

　　High-protein diet:

　　A high-protein diet is necessary to maintain healthy nails, and egg yolks are a good source of protein. Oatmeal, nuts, seeds, grains, and dairy products are rich in plant protein.

　　Eat more vegetables and fruits: fruits and vegetables should account for 50% of daily diet.

　　Supplement more nutrients: such as protein, vitamin A or vitamin A emulsion, brewer's yeast, calcium and magnesium, vitamin D, vitamin B, vitamin C, etc.

　　What foods should be avoided in metapателличный syndrome?

　　Avoid spicy foods.

　　(I) Treatment

　　There is no specific treatment for renal damage in metapателличный syndrome, general treatment is the same as other kidney diseases. For those who progress to end-stage renal disease, dialysis or kidney transplantation can be performed. Generally, the transplanted kidneys do not have recurrent basement membrane damage.

　　(II) Prognosis

　　Dislocation of patella and radial head can affect normal activity function. By middle age, about 1/3 of patients may have concurrent nephritis with proteinuria, which may eventually lead to renal failure and endanger life.