Cherry-red spot myoclonus syndrome

Besides this group of dysmorphic patients there is another type of sialidosis with normal physical appearance, absent or mild mental retardation, and manifestation in adolescence. Durand etal. (1977), O Brien (1977), Thomas etal. (1978) and Rapin etal. (1978) showed that patients, who presented mainly with ophthalmological problems, or with the so-called cherry-red spot—myoclonus syndrome, had a profoundly diminished neuraminidase activity and excreted abnormal amounts of sialyloligosaccharides in their urine. 

Clinical and Pathological Aspects. The disease is inherited as an autosomal recessive trait. Two major clinical forms are known. The more severe form, previously also known as mucolipidosis I, primarily occurs in infants and juvenile age groups. The less severe form is known as the cherry-red spot-myoclonus syndrome and occurs primarily in juvenile and older patients. Patients with the most severe form of mucolipidosis I may exhibit congenital... 

Patients with sialidosis show a striking syndrome characterized by action myoclonus, cerebellar ataxia and a macular cherry red spot similar to that in Tay-Sachs disease but with preserved intellect. 

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