Attacks can be precipitated by opioid analgesics, particularly in patients having undergone a cholecystectomy or bariatric surgery. Classification
Functional disorders of the gallbladder, bile duct and pancreas have been defined and classified by the Rome criteria for functional gastrointestinal disorders. The criteria outline three variants of functional disorders of the gallbladder, bile duct and pancreas, termed functional gallbladder disorder, functional biliary sphincter of Oddi disorder and functional pancreatic sphincter of Oddi disorder. All of the following criteria need to be met for as part of the definition of a functional disorder of the gallbladder:
the pain must be located in the upper part of the abdomen and/or the right upper quadrant of the abdomen
episodes of pain must last at least 30 minutes
the symptoms must be recurrent, and occur at differing intervals
the pain must incrementally increase to a "steady level"
the pain must be severe enough the patients daily activities are affected, or that the patient must attend the emergency department
the pain must not be relieved by any of bowel movements, change in posture, or antacids; and,
other structural disorders that could explain the symptoms must be excluded. Functional gallbladder disorder
Individuals are classified as having a functional gallbladder disorder if the above criteria are met, if the gallbladder is present, and if the testing of liver enzymes, conjugated bilirubin, and pancreatic enzymes (amylase and lipase) are normal.
Associated with the hair forelock, skin pigmentation can also appear in different parts of the body and limbs (suspected to be caused by the mutation in KIT). In parts of the body of some patients, congenital leukoderma is observed.Similar to other types of the syndrome, Type 1 displays heterochromia in some patients, sometimes complete or partial. If it happens to be partial, the differently colored iris is separated from the radial segment of the eye. Deficient iris stroma along with hypoplastic blue arises have also been found in some patients with Type 1. Another one of the symptoms is hearing loss, presenting in about 69% of cases. The types of hearing loss reported in patients differ over a great spectrum. Some of which could be bilateral or unilateral, sensorineural sometimes a combination of different ones in each ear. The most common loss types reported for Type 1 are profound and bilateral. Waardenburg Type 1 is estimated to cause 3% of overall congenital deaf children. Genetics
Type 1 Waardenburg Syndrome is a dominant autosomal disease, with extremely high penetrance of nearly 85%  Type 1, as well as type 3, are linked to a mutation in the PAX3 gene located in chromosome 2q35. This gene is responsible for encoding a transaction factor named Drosophila paired (noted as prd) resulting in essential proteins. These proteins are responsible for multiple functions in early human development such as stem cell pluripotency, as well as inhibition of differentiation when needed and cell-lineage specification, migration, and proliferation in the cells .