Autosomal Dominant Polycystic Kidney Disease (ADPKD) Diagnosis and Characteristics

Disease Prevalence and Characteristics

The American College of Nephrology recommends awareness of Autosomal Dominant Polycystic Kidney Disease (ADPKD) as the most common inherited kidney disorder with a prevalence of approximately 1 per 1000 in the general population 1, 2
ADPKD is characterized by bilateral kidney cysts that progressively enlarge and replace normal kidney tissue, with polycystic liver disease (PLD) being the most frequent extrarenal manifestation 1, 3
Liver cysts are present in >80% of ADPKD patients by age 30 years, with cysts being more common and liver volumes greater in women, increasing with age 4

The major causative genes are PKD1 (approximately 48% of screened families with truncating variants, 19% with nontruncating variants) and PKD2 (approximately 15% of screened families), influencing disease severity 1, 5
PKD2 mutations result in milder and later kidney enlargement, with chronic kidney disease stage 3 around age 55 years and kidney failure in the 70s—making this particularly relevant for elderly presentations 1, 6
Several minor genes (ALG9, GANAB, DNAJB11) are specifically associated with frequent or sometimes severe liver cysts alongside kidney manifestations 1, 7

The American College of Radiology recommends abdominal ultrasound as the first-line imaging modality for screening in elderly patients with incidentally detected kidney and liver cysts 8, 2
For patients aged ≥60 years with positive family history, ≥4 cysts in each kidney confirms the diagnosis 8, 2
When family history is unknown or imaging is equivocal, kidney MRI should be performed (>10 total cysts confirms diagnosis, <5 cysts rules it out for ages 16-40 years) 8
Genetic testing is particularly helpful when there are few kidney cysts, discordant imaging and kidney function, or negative family history 8

While isolated autosomal dominant polycystic liver disease (ADPLD) exists as a separate entity linked to PRKCSH and SEC63 genes with no or few kidney cysts, the presence of multiple cysts in both organs strongly favors ADPKD over isolated ADPLD 1, 6

Typical ADPKD (Class 1) is characterized by bilateral and diffuse distribution with mild, moderate, or severe replacement of kidney tissue by cysts, where all cysts contribute similarly to total kidney volume, according to the Kidney International guidelines 9
Atypical ADPKD (Class 2) includes lopsided presentation where ≤5 cysts account for ≥50% of total kidney volume, as described in the Kidney International journal 9
Screening for intracranial aneurysms should be considered if indicated by family history or symptoms, as recommended by the Kidney International guidelines 10

Acquired Cystic Disease (ACD) occurs in patients with advanced chronic kidney disease or on dialysis, and can be distinguished from ADPKD by assessing current kidney function, according to the Kidney International journal 9
The Mayo Imaging Classification calculates height-adjusted total kidney volume (htTKV) to classify disease severity into classes 1A through 1E for typical ADPKD (Class 1), with higher Mayo classes predicting faster progression to kidney failure, as described in the Kidney International guidelines 9
PKD2 variants are associated with a milder disease course, with CKD stage 3 around age 55 and kidney failure in 70s, making this genotype particularly relevant for elderly presentations, according to the Kidney International journal 10
Genetic testing can provide prognostic information, and if performed, should use nomenclature such as ADPKD-PKD1 or ADPKD-PKD2, as recommended by the Kidney International guidelines 11, 10