Distribution and development of CLN2 protein, the late-infantile neuronal ceroid lipofuscinosis gene product

Expression of the late-infantile neuronal ceroid lipofuscinosis (LINCL) gen e (CLN2) protein was investigated by immunoblotting and immunohistochemistr y in human brains and visceral organs of control individuals and of patient s with neuronal ceroid lipofuscinosis (NCL). Immunoblotting analyses showed reactivity in the cerebrum, liver, kidney, heart and colon of controls, wh ereas CLN2 protein was not detected in these organs in a LINCL patient. Imm unohistochemistry showed that the reactivity of the protein was ubiquitous in extracerebral organs as well as within the CNS, apparently corresponding to widely distributed deposition of lipopigments in LINCL. The expression of CLN2 protein in the cerebral cortex increased with development, and reac hed adult level after the age of 2. This development of expression seemed t o be related to the onset of LINCL at 2-4 years of age. We confirmed no imm unoreactivity in two of three patients with LINCL, who were diagnosed clini copathologically. One case showing combined ultrastructural morphology of f ingerprint profiles and curvilinear bodies had intermediate reactivity, sug gesting heterogeneity in clinical LINCL. Evaluation of the immunoreactivity of the CLN2 protein may be useful for characterization of a variant form.