B. 50% – Explanation
Polycystic kidney disease is usually inherited in an autosomal dominant fashion and hence 50% of
her children will be affected, regardless of gender. The autosomal recessive form is rare and usually
causes death in childhood.
ADPKD
Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of
kidney disease, affecting 1 in 1,000 Caucasians. Two disease loci have been identified, PKD1 and
PKD2, which code for
polycystin-1 and polycystin-2 respectively
| ADPKD type 1 | ADPKD type 2 |
| 85% of cases | 15% of cases |
| Chromosome 16 | Chromosome 4 |
| Presents with renal failure earlier |
The screening investigation for relatives is abdominal ultrasound:
Ultrasound diagnostic criteria (in patients with positive family history)
- two cysts, unilateral or bilateral, if aged < 30 years
- two cysts in both kidneys if aged 30-59 years
- four cysts in both kidneys if aged > 60 years
