Symptoms of the most common (and most serious) form of<unk>  typically appear in early infancy usually between the first three to six months of age.<unk>  then progresses rapidly from that stage, with typical cases involving intellectual disability, loss of previously acquired motor skills, feeding difficulties, abnormal muscle tone (i.e., initial floppiness - hypotonia - that may eventually translate into spasticity), poor head control, and megalocephaly (abnormally enlarged head). Paralysis, blindness, or seizures may also occur. There exists a much less common variant of<unk>  which is generally much less serious, and involves later onset of symptoms, which are often mild and nonspecific enough to go unrecognized as manifestations of<unk> 's disease. This variant does not seem to have any effect on lifespan, and is typically limited to minor cases of speech and motor skill development delay.
Canavan disease
Menkes disease
Akureyri disease
CADASIL
White dot syndromes
Keshan disease
Farber disease
Familial British dementia