Prevalence:

• 1 in 1,000 people carry the mutant gene.
• Clinical onset of this disorder is typically in the third to fifth decade of life.

Ultrasound diagnosis:

• The kidneys are enlarged and hyperechogenic, but smaller than in autosomal recessive disease.
• Renal pelvises can be visualised.
• Bladder and amniotic fluid volume are normal.

Associated abnormalities:

• The incidence of chromosomal abnormalities and genetic syndroms is not increased.
• Associated with hepatic, pancreatic or ovarian cysts.

Investigations:

• Detailed ultrasound examination.
• Genetic testing: the disease is caused by mutations in the PKD1 gene (85% of cases) on chromosome 16p13.13 and PKD2 gene (15% of cases) on chromosome 4q13.23. Prenatal diagnosis in affected families can be carried out by first-trimester chorion villous sampling.

Follow up:

• Ultrasound scans every 4 weeks to assess amniotic fluid volume.
• Ultrasound examination of parents’ kidneys.

Delivery:

• Standard obstetric care and delivery.

Prognosis:

• In counselling affected parents with ADPKD, it should be emphasized that the prenatal demonstration of sonographically normal kidneys does not necessarily exclude the possibility of developing polycystic kidneys in adult life.
• Dialysis and transplant are the treatment options when the pathology becomes symptomatic in the third to fifth decades of life.

Recurrence:

• Risk of recurrence: 50%.