What is the most common inherited kidney disease?

Xiao Wang's father was diagnosed with uremia at the end of last year. At the beginning of this month, Xiao Wang's company organized a physical examination, and the examination found "multiple renal cysts in both kidneys". The physical examination center recommended that Xiao Wang go to the hospital for a reexamination. Xiao Wang went to the hospital for further examination. After the examination, the doctor asked Xiao Wang: "Does anyone in your family have kidney disease?" After Xiao Wang told the doctor the truth, the doctor told him: "You have the most common hereditary kidney disease - polycystic kidney disease."

Polycystic kidney disease, also known as Potter (Ⅰ) syndrome, Perlmann syndrome, congenital renal cystic tumor disease, cystic kidney, bilateral renal dysgenesis syndrome, benign multilocular cystic tumor of the kidney, is an autosomal hereditary kidney disease named after one or more large cysts on the kidney. Clinically, it can be divided into three types according to the size and location of the cyst: small, medium and large. The most common is small polycystic kidney disease, accounting for 50% to 60% of the total number of polycystic kidneys in adults, which can be divided into autosomal dominant polycystic kidney disease and autosomal recessive polycystic kidney disease.

Polycystic kidney disease is insidious in its early stages. When patients are young, their kidneys are normal or slightly larger in size. As the cysts continue to grow, they affect normal renal function, leading to symptoms such as bilateral kidney enlargement, renal pain, hematuria, and hypertension. When it develops to the end-stage renal disease stage, it is commonly known as uremia, and renal replacement therapy is required. Therefore, early diagnosis and treatment of polycystic kidney disease is particularly important.

The diagnostic methods for polycystic kidney disease include collection of clinical data (family history, symptoms and signs), imaging examinations and genetic diagnosis. Renal ultrasound is currently the preferred imaging examination method.

Ultrasound manifestations of adult polycystic kidney disease: Both kidneys are irregularly enlarged and morphologically abnormal, the kidneys are filled with liquid dark areas of varying sizes, the normal renal structure disappears, the cysts are not connected to each other, and sometimes the renal parenchyma becomes significantly thinner and cannot even be found.

Genetic diagnosis of polycystic kidney disease[1]:

(1) Autosomal dominant polycystic kidney disease: Currently, long-fragment PCR + next-generation sequencing technology is mainly used to detect mutations in patients with autosomal dominant polycystic kidney disease. The detection rate of polycystic kidney gene mutations is about 90%, and 10% of mutations cannot be detected. It is suitable for sporadic patients with no family history, atypical imaging manifestations, living kidney donors with positive family history, early diagnosis of suspected pediatric patients, and reproductive genetic counseling. Genetic testing is not recommended for individuals under 15 years old with a family history of autosomal dominant polycystic kidney disease.

(2) Autosomal recessive polycystic kidney disease: Genetic diagnosis is the gold standard for diagnosing autosomal recessive polycystic kidney disease. It is recommended that all children with autosomal recessive polycystic kidney disease in the imaging studies undergo genetic testing to confirm the diagnosis. The PKHD1 gene coding region is long and has many mutation sites, making detection more difficult. The detection of DZIPIL gene mutations is relatively easy. When the imaging manifestations are nonspecific and/or combined with other ciliary syndrome manifestations, modular screening of genes related to cystic lesions is recommended.

At present, the main treatment for polycystic kidney disease is oral nonsteroidal anti-inflammatory drugs, immunosuppressants, and glucocorticoids to control the size, location, and other symptoms of cysts. In addition, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers are clinically needed to control the development of cysts and thus relieve renal dysfunction. These drugs can be taken at the same time to reduce or prevent glomerular cystic changes. For patients with polycystic kidney disease with faster disease progression, tolvaptan can be used for treatment under the guidance of a doctor.

In addition, traditional Chinese medicine can be used to treat polycystic kidney disease. Polycystic kidney disease is generally classified as a symptom in traditional Chinese medicine. Insufficient innate endowment, excessive fatigue, emotional disorders, etc. can easily lead to kidney deficiency, liver dysfunction, and spleen dysfunction. The causes of polycystic kidney disease are often mainly qi stagnation, blood stasis, and phlegm and dampness. Long-term phlegm and dampness will deplete the vital energy, eventually leading to kidney deficiency, and toxins in the body cannot be discharged in time. In traditional Chinese medicine treatment, the methods of regulating qi, activating blood circulation, unblocking collaterals, resolving phlegm, softening hard masses and dispersing nodules are often used. At the same time, drugs that strengthen the spleen and kidney, remove dampness, eliminate turbidity and detoxification are also often used as auxiliary treatment.

The prognosis of patients with polycystic kidney disease who develop complications is much worse than that of patients who do not develop complications. Common complications of polycystic kidney disease include: (1) Urinary tract infection: including cystitis, pyelonephritis, cyst infection and perirenal abscess. Among them, pyelonephritis and cyst infection are more difficult to distinguish. If the patient has white blood cell casts and the conventional antibacterial treatment of urinary tract infection is effective, it can be diagnosed as pyelonephritis; if the blood culture is positive and there is local tenderness, it may be a cyst infection. (2) Kidney stones and intrarenal calcification: If there is increased pain, colic or gross hematuria, stones may be complicated. According to statistics, the incidence of this disease is about 20%, and the main components are calcium and uric acid. (3) Hypertension: When polycystic kidney disease develops into renal failure, almost all patients will develop hypertension. Long-term hypertension will not only lead to decreased kidney function, but also increase the risk of heart disease and stroke.

Polycystic kidney disease is a hereditary disease. For people with a family history of polycystic kidney disease, regular kidney ultrasound examinations, blood urea nitrogen and creatinine levels should be performed, and genetic testing should be performed when necessary to detect polycystic kidney disease as early as possible.