Prune-belly syndrome is characterized by a triad of abnormalities that include, absence of the lower portion of the rectus abdominis muscle and the inferior and midportions of the oblique muscles (causing the skin of the abdomen to wrinkle like a prune), undescended testicles, an expanded bladder and problems in the upper urinary tract, which may include the bladder, ureters, and kidneys. Prognosis may vary from death in utero to a near-normal life expectancy. Prune-belly anomalies are rare and occur mostly in boys. Males suffering from PBS have been noted to be sterile. Several cases have been reported in girls (incomplete prune-belly syndrome) but usually with milder symptoms.
Absence of abdominal muscles with urinary tract abnormality and cryptorchidism is caused by homozygous mutation in the CHRM3 gene. The M3 cholinergic receptor mediates autonomic neurotransmission in the ocular iris pupillary sphincter and the detrusor muscle in humans.