Neuraminidase Deficiency

Clinical Characteristics
Ocular Features: 

A cherry red spot is may be seen in late childhood or early adolescence.  It occurs in nearly 100% of patients with type I while only 75% of type II patients have this feature possibly because their early death from the more severe systemic disease prevents full ascertainment.  Visual acuity is reduced, sometimes severely.  Some but not all individuals have corneal and lens opacities.  A subtle corneal haze has also been seen.  Nystagmus has been reported. 

Systemic Features: 

This is a neurodegenerative disorder with progressive deterioration of muscle and central nervous system functions.  Myoclonus, mental deterioration, hepatosplenomegaly, muscle weakness and atrophy are common.  The defect in neuraminidase activity leads to abnormal amounts of sialyl-oligosaccharides in the urine.  Spinal deformities such as kyphosis are common.  Deep tendon reflexes are exaggerated.  Ataxia and hearing loss may be present.  Coarse facies, a barrel chest, and short stature are characteristic.  Hepatic cells contain numerous vacuoles and numerous inclusions.

Sialidosis types I and II are both caused by mutations in the neuroaminidase gene.  Type I is associated with milder disease than type II which has an earlier age of onset and may present in infancy or even begin in utero.  Early death within two years of age is common in the congenital or infantile forms.  There is, however, significant variability in age of onset and the course of disease among types. 


The sialidoses are autosomal recessive lysosomal storage disorders resulting from mutations in the NEU1 gene (6p21.3) which lead to an intracellular accumulation of glycoproteins containing sialic acid residues.  Both types I and II are caused by mutations in the same gene. 

Treatment Options: 

Treatment is focused on symptom management. 

Article Title: 


Zou W, Wang X, Tian G. Fundus autofluorescence and optical coherence tomography of a macular cherry-red spot in a case report of sialidosis. BMC Ophthalmol. 2016 Mar 22;16(1):30.

PubMedID: 27004518

Heroman JW, Rychwalski P, Barr CC. Cherry red spot in sialidosis (mucolipidosis type I). Arch Ophthalmol. 2008 Feb;126(2):270-1.

PubMedID: 18268224

Goldberg MF. Macular cherry-red spot and corneal haze in sialidosis (mucolipidosis type 1). Arch Ophthalmol. 2008 Dec;126(12):1778; author reply 1778.

PubMedID: 19064869

Federico A, Cecio A, Battini GA, Michalski JC, Strecker G, Guazzi GC. Macular cherry-red spot and myoclonus syndrome. Juvenile form of sialidosis. J Neurol Sci. 1980 Nov;48(2):157-69.

PubMedID: 7431038