What gastrointestinal (GI) disease is associated with blue lunulae?
The lunula is the moon-shaped white area present at the proximal nail plate. Blue lunulae are seen in Wilson disease (hepatolenticular degeneration), which is caused by an autosomal recessive defect in ATP7B and copper transport. Copper accumulates in the liver, brain, cornea, skin, nails, and other tissues. Patients may also demonstrate pretibial hyperpigmentation. Kayser-Fleischer rings (brown to green circle of pigment in Descemet membrane of the eye) are pathognomonic of Wilson disease.