SNP Shot: Genomic Insights

Polycystic kidney disease (PKD) is a condition affecting the kidneys and potentially other organs. It's characterized by the development of cysts, fluid-filled sacs, within the kidneys. These cysts impair the kidneys' ability to filter waste from the blood, leading to kidney enlargement and potentially kidney failure. Cysts can also form in other organs, most commonly the liver.

Common complications associated with PKD include high blood pressure (hypertension), back or side pain, blood in the urine (hematuria), recurring urinary tract infections, kidney stones, and heart valve problems. Individuals with PKD also face a heightened risk of developing aneurysms, abnormal bulges, in the aorta (a major blood vessel) or in blood vessels at the base of the brain. Aneurysm rupture can be life-threatening.

PKD has two primary forms, distinguished by age of onset and inheritance patterns. Autosomal dominant PKD (ADPKD) usually presents symptoms in adulthood, although kidney cysts are often present from birth or childhood. ADPKD is further classified into type 1 and type 2, depending on the underlying genetic cause. Autosomal recessive PKD (ARPKD) is much rarer and often fatal in early life. Symptoms typically appear at birth or during infancy.

Inheritance:

Most PKD cases follow an autosomal dominant inheritance pattern. Individuals with ADPKD are born with one mutated copy of either the PKD1 or PKD2 gene in each cell. Approximately 90% of the time, the affected individual inherits the mutation from a parent who also has ADPKD. In the remaining 10% of cases, the mutation is new and occurs spontaneously in the individual, with no family history of the disorder. While only one mutated gene copy is enough to cause ADPKD, a second mutation in the other copy of PKD1 or PKD2 may accelerate cyst growth and worsen the disease. The progression of cyst enlargement and kidney function decline varies greatly and may be influenced by other, yet unidentified, genetic factors. PKD can also be inherited in an autosomal recessive manner. In ARPKD, affected individuals have two altered copies of the PKHD1 gene in each cell. Parents of a child with ARPKD are unaffected carriers, each possessing one copy of the altered gene.