New Spielmeyer-Vogt variant with granular inclusions and early brain atrophy

Three females in 2 families were originally diagnosed with Spielmeyer-Vogt disease (SVD). The clinical course was different from SVD, with vision well preserved until age 10 years, and learning rather than visual difficulties the marker at the onset. Later, regression was unusually rapid, including global dementia, blindness, aphasia, and finally loss of self-feeding and ambulation between ages 12-18 years. MRI scan in patient 3 documented brain atrophy between ages 8-10 years. Position Emission Tomography (PET) scanning with fluorodeoxyglucose in patients 2 and 3 showed diffusely decreased or absent cortical glucose metabolism, comparable at ages 12 and 18 years, respectively, to the results found in the oldest typical SVD case tested at age 29 years. Fine granular inclusions, instead of the expected fingerprint inclusions, were demonstrated by electron microscopy of lymphocytes, conjunctiva, and skin. Usual markers on chromosome 16p12 were not present in the first family tested. The clinical course, with nonspecific initial behavior difficulties, late onset of visual decline followed by fast global regression, progressive brain atrophy, decreased cortical glucose utilization as shown by PET scanning, and granular tissue inclusions, suggest a genetic variant of SVD.