A lysosomal storage disease, identified as a mucopolysaccharidosis (MPS), was diagnosed in a free-living Kaka (Nestor meridionalis), an endemic New Zealand parrot, which exhibited weakness, incoordination, and seizures. Histopathology showed typical colloid-like cytoplasmic inclusions in Purkinje cells and many other neurons throughout the brain. Electron microscopy revealed that storage bodies contained a variety of linear, curved, or circular membranous profiles and electron-dense bodies. Because the bird came from a small isolated population of Kaka in the northern South Island, a genetic cause was deemed likely. Tandem mass spectrometry revealed increased levels of heparan sulfate-derived disaccharides in the brain and liver compared with tissues from controls. Enzymatic assays documented low levels of iduronate-2-sulfatase activity, which causes a lysosomal storage disorder called MPS type II or Hunter syndrome. A captive breeding program is currently in progress, and the possibility of detecting carriers of this disorder warrants further investigation.
Keywords: Enzymology; Hunter syndrome; lysosomal storage disease; mass spectrometry; mucopolysaccharidosis II; parrot; ultrastructure.
© Wildlife Disease Association 2021.