The phenotypes that are associated with the common forms of polycystic kidney disease
(PKD)—autosomal dominant (ADPKD) and autosomal recessive (ARPKD)—are highly
variable in penetrance. This is in terms of severity of renal disease, which can range from
neonatal death to adequate function into old age, characteristics of the liver disease, and
other extrarenal manifestations in ADPKD. Influences of the germline mutation are at the
genic and allelic levels, but intrafamilial variability indicates that genetic background and …