Polycystic Kidney Disease: Autosomal Dominant and Recessive

Question 1

Definition

Answer 1

Genetic condition where the kidneys develop multiple fluid-filled cysts through out renal parenchyma. Leads to bilateral enlargement + kidney function is also significantly impaired.

Question 2

Autosomal Dominank PKD Aetiology

Answer 2

PKD-1: Chromosome 16 (85%)
PKD-2: Chromosome 4 (15%)

Question 3

Autosomal Dominant PKD Epidemiology

Answer 3

MALES
20-30 years

Question 4

Autosomal recessive Aetiology

Answer 4

Genes on chromosome 6 - rarer + more severe.
- Often presents in pregnancy with oligohydramnios as the foetus does not produce enough urine

Question 5

Autosomal recessive Epidemiology

Answer 5

Disease of infancy or prebirth with increased mortality
- many congenital abnormalities (e.g. Potters sequence = flattened nose, clubbed feet)

Question 6

Pathophysiology

Answer 6

PKD1+2 code for polycystin (Ca2+ channel). In cilia of nephron, when filtrate passes, cilia move + polycystin on cilia OPEN. Ca2+ influx INHIBITS EXCESSIVE GROWTH
In PKD mutation = Ca2+ decrease in influx = leads to excess cilia growth = CYSTS

Question 7

Signs and Symptoms

Answer 7

BILATERAL FLANK/ BACK OF ABDO PAIN
+/- HTN
Haematuria
* In autosomal recessive presents with oligohydramnios as the foetus doesn’t produce enough urine which leads to underdevelopment of the lungs *

Question 8

Extrarenal manifestations

Answer 8

Circle of Willis = Berry Cerebral aneurysms = SUBARACHNOID HAEMORRHAGE
Hepatic, splenic, pancreatic, ovarian and prostatic cysts
Cardiac valve disease (mitral regurgitation)
Colonic diverticula
Aortic root dilatation

Question 9

Diagnosis

Answer 9

FIRST LINE = Kidney USS
- enlarged bilateral kidneys with multiple cysts
GOLD STANDARD = Genetic testing

Question 10

Treatment

Answer 10

Non curative
- Tolvaptan can slow development of cysts in ADPKD = VASOPRESSIVE ANTAGONIST
Manage Sx:
- Antihypertensives
- Analgesia for renal colic
- Abx
- Dialysis = ESRF
- Renal transplant

Question 11

Complications

Answer 11

Chronic loin pain
Hypertension
Cardiovascular disease
Gross haematuria can occur with cyst rupture (this usually resolves within a few days
Renal stones are more common in patients with PKD
End-stage renal failure occurs at a mean age of 50 years