Parkin-positive autosomal recessive juvenile Parkinsonism with alpha-synuclein-positive inclusions.

Objective: To report an autopsy case of an autosomal recessive juvenile parkinsonism patient with a homozygous exon 3 deletion in the parkin gene and alpha-synuclein-positive inclusions.

Methods: The representative areas of the brain were embedded in paraffin, stained with hematoxylin-eosin, Klüver-Barrera, and Gallyas-Braak stainings. Immunohistochemically, some of the specimens were used for immunostaining with the antibodies to alpha-synuclein, ubiquitin, and phosphorylated tau (AT8). Immunoreaction was visualized by the streptavidin-biotin-peroxidase complex method.

Results: Histologically, the lesions of the brain were limited to the dopaminergic neuron system such as the substantia nigra (SN) and locus ceruleus. Melanin-containing neurons in the pars compacta of the SN were moderately to severely depleted, accompanied by gliosis. In the locus ceruleus, neurons were mildly decreased and extraneuronal melanin pigments were seen. Lewy bodies were not observed in the neuropils of the pars compacta of the SN or locus ceruleus. However, basophilic inclusion bodies were only occasionally observed in the neuropils of the pedunculopontine nucleus in the mesencephalic reticular formation. Immunohistochemistry with antibodies to alpha-synuclein and ubiquitin showed alpha-synuclein- and ubiquitin-positive inclusions in the neuropils of the pedunculopontine nucleus, which had a doughnut or round shape.

Conclusions: A variety of parkin gene abnormalities may produce pathologic differences in the degree and distribution of neuronal degeneration, including the absence or presence of Lewy bodies. A relationship between parkin-induced parkinsonism and idiopathic Parkinson disease (PD) may exist.