Clinical and Biochemical Abnormalities in Porcine GM 2 -Gangliosidosis

Progressive clinical changes of GM 2 -gangliosidosis in a herd of inbred Yorkshire swine were reduced postnatal growth rate; incoordination, usually evident at 3 months of age; numerous, gray-white spots scattered through the retina; prominent, dark blue cytoplasmic granules in many neutrophils; and an increased frequency of azurophilic granules in lymphocytes. There was less N -acetyl-β-D-hexosaminidase in tissue homogenates from affected than from normal pigs, but there was more in serum from affected pigs than in serum from either carrier or normal pigs. The serum enzyme assay was a reliable test to distinguish carrier pigs from normal pigs; carrier pigs had moderate enzyme activity, and normal pigs had the lowest enzyme activity. The frequency of affected and carrier pigs in this herd suggested that porcine GM 2 -gangliosidosis is a familial disease transmitted as an autosomal recessive trait. Cerebral cortical ganglioside was about two times higher than normal in the stillborn and newborn affected pigs and three to four times higher than normal in the 140- to 167-day-old moribund affected pigs. The major cerebral cortical gangliosides in control pigs were GT 1 , GD 1b , GD 1a , and GM 1 , with only trace amounts of GM 2 -ganglioside. GM 2 -ganglioside was as much as 58% of the total gangliosides in the brains of moribund affected pigs. The clinical and biochemical features of porcine GM 2 -gangliosidosis closely resembled those of the juvenile (type AB) form of the disease in man.