Autosomal dominant polycystic kidney disease
What is Autosomal dominant polycystic kidney disease?
Autosomal dominant polycystic kidney disease (ADPKD) is a condition that affects approximately 12 million people worldwide. It is one of the most common genetic diseases. This disease causes cysts that destroy kidney tissue, gradually requiring dialysis and transplants. Symptoms vary from individual to individual depending on the number of cysts and the extent of the disease. Apart from transplantation, most treatments are only intended to reduce the symptoms and complications associated with the disease.
A genetic disease: the causes of ADPKD
The risk of transmitting the mutated gene from a parent to their children is 50%. In 10% of cases, ADPKD appears when there is no family history. This is called a de novo mutation. An ultrasound scan reveals cysts in the kidneys of the affected parent.
The disease is due to the mutation of two genes:
The PKD1 gene is located on the short arm of chromosome 16 and codes for polycystin-1 protein. Mutations in the PKD1 gene are responsible for 85% of cases of ADPKD. Mutations in the PKD1 gene are associated with a poorer renal prognosis than PKD2 mutations.
The PKD2 gene is located on the long arm of chromosome 4 and encodes polycystin-2. PKD2 mutations are responsible for 15% of ADPKD cases.
Rare cases of ADPKD may not be related to any of these genes, as has been observed in some cases of the condition.
Symptoms and evolutions of ADPKD
Autosomal dominant polycystic kidney disease is a systemic disease, which means it can affect several organs. Events secondary to the development of cysts are to be distinguished from events independent of cyst formation.
In ADPKD, the revealing symptoms may be lumbar pain in 7 out of 10 patients and abdominal pain in about 60% of patients. Other symptoms also include nephritic colic, hematuria (blood in the urine), and cystic infection. But the disease can also go unnoticed.
Consequences of ADPKD
Renal cysts multiply, grow and gradually destroy the renal parenchyma. Kidney destruction is responsible for chronic kidney failure. Cysts disrupt the normal shape of the kidney. This alteration is responsible for high blood pressure (hypertension), lithogenesis (stone formation) and promotes urinary tract infections. Increased renal volume is responsible for compression and pain. Increased cyst volume can erode small vessels and cause painful intracystic hemorrhage or hematuria. Lumbar pain is common.
Acute pain is associated with complications: bleeding, kidney stones, and urinary tract infections. Chronic pain is most often secondary to the increase in volume of the kidneys, which puts pressure on the kidney capsule or pulls on the pedicle.
ADPKD and pregnancy
Pregnancy is possible in women with polycystosis of the kidney. In the absence of high blood pressure and chronic renal failure, the vast majority of pregnancies occur without maternal or fetal complications.
Possible complications are the occurrence or aggravation of high blood pressure, the occurrence of preeclampsia with its maternal and fetal complications. Pregnancy can lead to impaired renal function if there is pre-existing chronic renal failure.
The risk of disease transmission is a parameter to be taken into account. You should not hesitate to meet a team of geneticists to benefit from appropriate genetic counselling. Pregnancy should be managed by multidisciplinary experienced teams. Close collaboration between the nephrological and gynaecological-obstetrical team is the key to a successful pregnancy.
Published Feb 27, 2019