Symptoms vary with age of onset and may include:
- jaundice at (or shortly after) birth
- an enlarged spleen and/or liver (hepatosplenamegaly)
- difficulty with upward and downward eye movements (Vertical Supranuclear Gaze Palsy).
- unsteadiness of gait, clumsiness, problems in walking (ataxia)
- difficulty in posturing of limbs (dystonia)
- slurred, irregular speech (dysarthria)
- learning difficulties and progressive intellectual decline (Cognitive dysfunction - "dementia")
- sudden loss of muscle tone which may lead to falls (cataplexy)
- tremors accompanying movement and, in some cases, seizures
- Attention Deficit Disorder (ADD)
- Learning Disability
- Retardation
- Delayed Development
Type C is the most variable form of the disease. Symptoms may appear and then disappear. Some symptoms may never appear. The rate of progression of the disease is different from person to person. The rate of progress for an individual will change over time.
Type C is often incorrectly diagnosed. Some of the common errors are:
Vertical Supranuclear Gaze Palsy (VSGP or VGP) is highly suggestive of Type C. VSGP is the inability to move the eyes up and down. Parents often notice this when their child walks up and down stairs, watches TV while sitting on the floor, or in similar situations - the child tilts their head to see instead of moving their eyes. Liver or spleen problems in the first few months after birth are also highly suggestive of Type C.