MUCOPOLYSACCHARIDOSIS II (MPS II) IN A FREE-LIVING KAKA (NESTOR MERIDIONALIS) IN NEW ZEALAND.

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.

Clinical and morphologic features of mucopolysaccharidosis type II in a dog: naturally occurring model of Hunter syndrome.

A 5-year-old male Labrador Retriever had progressive incoordination, visual impairment, and exercise intolerance. Coarse facial features, macrodactylia, unilateral corneal dystrophy, generalized osteopenia, progressive neurologic deterioration, and a positive urine spot test for acid mucopolysaccharides suggested mucopolysaccharidosis. Intracytoplasmic vacuoles were most prevalent in epithelial cells, endothelial cells, and histiocytes of liver, kidney, thyroid gland, and spleen. Ultrastructural examination disclosed electron-lucent floccular to lamellar membrane-bound storage material characteristic of mucopolysaccharides. Periodic acid-Schiff-positive intracytoplasmic material was identified in multiple neurons in the medulla, pontine nucleus, cerebellum, and spinal gray matter horns. Biochemical assays identified a deficiency in iduronate-2-sulfatase (IDS) activity in cultured dermal fibroblasts compared with normal dogs. Hair root analysis for IDS showed that the dam was a carrier of X-linked Hunter syndrome and that a phenotypically normal male littermate of the affected dog was normal. This is the first report of Hunter syndrome or mucopolysaccharidosis type II in a dog.