Gangliosidosis in Emus (Dromaius novaehollandiae)

Abstract

A 6-month-old female emu (Dromaius novaehollandiae) died following acute central nervous system signs. Hematoxylin-and-eosin-stained sections revealed that neurons of the brain were distended with nonstaining 1-to-2-microns vacuoles. Ultrastructural examination of the affected neurons revealed numerous membranous cytoplasmic bodies (MCBs) similar in appearance to the MCBs seen in mammalian gangliosidoses. A full sibling of this emu was donated for study. This 7-month-old female emu was stunted compared with hatchmates. Neurologic examination revealed hypermetric gait, persistent head tremor, and mild ataxia. No gross lesions were evident at postmortem. Histopathologic and electron microscopic findings were similar to those in the index case in that swollen, pale neurons were present in the cerebrum, pons, medulla, cerebellum, spinal cord, spinal ganglia, autonomic ganglia, myenteric plexus, and ganglion cell layer of the retina. Analysis of brain gangliosides of the affected 7-month-old emu revealed 14- and 25-fold increases of GM1 and GM3 gangliosides, respectively, compared with control emus. The total brain ganglioside sialic acids were, on a wet weight basis, 519 micrograms/g (control A), 658 micrograms/g (control B), and 1800 micrograms/g (affected emu). The familial association seen with this condition suggests that emus are affected by an inherited disorder similar to mammalian gangliosidoses.

Unusual Gangliosidosis in Emu (Dromaius novaehollandiae)

“…One of us (A.J.B.) previously reported the presence of membranous cytoplasmic bodies in the neurons of affected emus (Bermudez et al, 1995) and suggested that these animals may suffer from a lysosomal storage disease. The present findings showing highly significant increases in the content of all ganglioside fractions in the affected emu brain are consistent with this notion.…”

“…The finding that the affected emu brain contains GM2 (even though the total amount of this monosialoganglioside is small in comparison with all other ganglioside components) first led us to consider the possibility of one form of GM2-gangliosidosis. This possibility was discounted following analysis of the total hexosaminidase and hexosaminidase A activities, which revealed normal enzyme levels for the affected and control emu brains (Bermudez et al, 1995). The occurrence of a GM1-gangliosidosis was also excluded by determination of the activity of acid /3-galactosidase, which only showed a partial decrease to 43% of normal levels (Bermudez et al, 1995).…”

“…The majority of the birds seemingly died related to the disease described in this report; the controls used for our study had been euthanized with unrelated diseases or trauma. A description of the pathological lesions of the affected birds has been reported elsewhere (Bermudez et al, 1995). Four of the seven affected emus were progeny from a breeder pair in an emu farm in Missouri, whereas two others were progeny from a breeder pair in Illinois.…”

“…Recently, one of us (A.J.B.) reported a unique neuronal storage disease involving glycolipids that occur in the emu (Dromaius novaehollandiae) (Bermudez et al, 1995). The symptoms ofthe affected birds include progressive neurological symptoms such as ataxia as well as severe hemorrhage into the body cavity originating from liver or large muscles resulting in an early death of the young bird.…”

Morphological, Biochemical and Molecular Biology Approaches for the Diagnosis of Lysosomal Storage Diseases

“…16,36,53,59 Depending on the mutation site and/or defective gene, they may be presented as an infantile or an adult form. They may be manifested as a neurological disorder, hepatosplenomegaly, cloudy corneas or by skeletal abnormalities and as a combination of the above.…”