A condition, also known as agenesis (failure of development) of the gallbladder which occurs in approximately one out of every 1,000 people. Gallbladder agenesis is an isolated abnormality in more than two-thirds (70%) of people with agenesis. The person with isolated agenesis of the gallbladder is healthy. No treatment is needed. The prognosis (outlook) is excellent. Gallbladder agenesis occurs in association with additional malformations in the remaining (30%) of cases which fall into two groups: one (9%) with atresia (failure of opening) of the bile ducts and the other (21%) with normal bile ducts but distant abnormalities such as ventricular septal defect (a hole between the ventricles of the heart), imperforate anus (blind rectum with no anus), malrotation of the gut (failure of the intestines to rotate normally during embryonic development), renal agenesis (absence of a kidney), and syndactyly (fusion of fingers).