Abstract

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most frequent genetic disease, characterized by progressive development of bilateral renal cysts. Two causative genes have been identified: PKD1 and PKD2. ADPKD phenotype is highly variable. Typically, ADPKD is an adult onset disease. However, occasionally, ADPKD manifests as very early onset disease. The phenotypic variability of ADPKD can be explained at three genetic levels: genic, allelic and gene modifier effects. Recent advances in molecular screening for PKD gene mutations and the introduction of the new next generation sequencing (NGS)- based genotyping approach have generated considerable improvement regarding the knowledge of genetic basis of ADPKD.

The purpose of this article is to provide a comprehensive review of the genetics of ADPKD, focusing on new insights in genotype-phenotype correlation and exploring novel clinical approach to genetic testing. Evaluation of these new genetic information requires a multidisciplinary approach involving a nephrologist and a clinical geneticist.

Abstract

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic disorder related to kidney. ADPKD is usually easy to diagnose in people who have a family history of ADPKD’s developing typical symptoms, including flank, abdominal pain or macroscopic hematuria. In this setting, diagnosis in adults at risk for ADPKD is commonly performed by ultrasonography, which reveals two enlarged kidneys with multiple bilateral cysts. ADPKD may be more difficult to diagnose in the absence of family history or in subjects with atypical presentation, including asymmetric or focal renal imaging findings, discordant disease within family, early onset of ADPKD and development of ESRD before 30 yr of age. The presence of “a total of three or more renal cysts” for at-risk subjects aged 15-39 years and “two cysts or more in each kidney” for at-risk subjects aged 40-59 years are sufficient for the diagnosis of ADPKD. The “absence of any renal cyst” is sufficient for disease exclusion only for at-risk subjects aged 40 years or older. If the family history is negative, the diagnosis of ADPKD can be made in a patient with enlarged kidneys, numerous cysts, presence of liver cysts and absence of findings suggesting a different cystic disease. If the imaging diagnosis is not clear or showing atypical manifestations in subjects, molecular genetic testing should be performed.