Scalp hair, eyelashes, and eyebrows are silver.
Sun exposure leads to pronounced and long-lasting skin tanning. The age at
onset of neurologic signs can range from 1 month to 11 years and include
severe muscular hypotonia, ataxia, seizures, hyperreflexia or hyporeflexia,
spastic or flaccid hemiplegia or quadriplegia, and ocular features (e.g.,
congenital amaurosis, nystagmus, diplopia, pupillary areflexia). Mental
retardation with delayed psychomotor development usually is obvious in the
first month of life. Magnetic resonance imaging can demonstrate cerebellar