Background: Niemann–/INS;Pick type C (NPC) is a rare neurovisceral lipid storage disorder of autosomal inheritance, caused by abnormal intracellular cholesterol metabolism. In patients with adult form of NPC, psychiatric symptoms may precede neurological symptoms. If patients present with psychiatric manifestation of adult onset NPC, diagnosis is delayed.

Background: Mutations in the mitochondrial DNA are maternally inherited and may lead to multisystem disorders. A tissue-specific threshold-level of the respective mtDNA-mutation load must be exceeded to give rise to a phenotypic manifestation.

Background: The characteristic symptoms of normal pressure hydrocephalus are dementia, urinary incontinence and gait disturbance. Psychiatric symptoms may also occur but appear usually after the characteristic symptoms.

Introduction: Familial spastic paraplegia with thin corpus callosum is related to mutations in the genes SPG11, 15 and 18. Mutations in the SPG11 gene have also been described in amyotrophic lateral sclerosis with young onset and a relatively benign course.

Background: Niemann–/INS;Pick type C (NPC) is an autosomal recessive, neurodegenerative lysosomal storage disorder. It occurs at a frequency of approximately 1:120,/INS;000 live births, but is probably underdiagnosed, especially in the case of adult manifestation. NPC disease shows variable clinical pictures (neurological, psychiatric and systemic symptoms) and manifestations in different age groups. In teenagers and adults, dementia and psychiatric presentations may overshadow motor dysfunction. Vertical supranuclear gaze palsy (VSGP) is a very specific sign, but often missed, if the oculomotor system is not examined carefully. There have been no investigations about clinical abnormalities in heterozygote carriers of NPC so far.