Heritability and biochemistry of gangliosidosis in emus (Dromaius novaehollandiae)

The progeny of two emu breeder pairs, which had a history of producing offspring with gangliosidosis, were monitored for 15 mo. DNA fingerprinting revealed that individuals in each breeder pair were not related to each other. One breeder pair had 13 progeny that reached or exceeded the age of 1 mo, and six of these progeny developed gangliosidosis. The mean age at which these affected emus were euthanatized, with distinct neurologic disease, or died was 5.7 mo. The second emu pair had 13 progeny, seven of which developed gangliosidosis, with a mean age of euthanasia/death of 4.6 mo. Affected emus died or were euthanatized from 2 to 8 mo of age. The primary clinical sign in the affected emus was mild to severe ataxia. Severe hemorrhage into the body cavity or the muscles of the thigh was noted in 8 of 13 of the affected emus. Brain ganglioside levels were evaluated in six of the affected emus and six controls. Significant increases (P < 0.05) in gangliosides GM1 and GM3 were noted, with 2.3- and 4.9-fold increases in these two gangliosides, respectively, in affected emus. Furthermore, the diseased emu brains contained ganglioside GM2, whereas this monosialoganglioside was undetectable in the brains of normal controls. Total mean brain ganglioside sialic acid in affected emus was increased 3.3-fold in comparison with controls. Serum chemistries revealed elevated cholesterol and decreased uric acid levels in affected emus. Gangliosidosis in emus is an inherited disease process that, in the current study, caused 50% mortality in the progeny of two emu breeder pairs. The elimination of this lethal gene from emu breeder stock is essential for the long-term economic viability of the United States emu industry.