Mucolipidosis type IV


Autosomal recessive

Inheritance from both parents will result in the disease

Age range at onset:

Within first year

Specialists you may see:


Mucolipidosis type IV is most commonly found in the severe form, with symptoms including delayed development of motor skills such as sitting, standing, walking and grasping. Intellectual disability is also common, alongside swallowing and speech difficulties and hypotonia (weak muscle tone) leading to spasticity. Vision is increasingly impaired in the first 10 years of life, with severe sight loss or blindness by teenage years.

Affected individuals usually survive to adulthood, although this condition may cause a shortened lifespan. Those with the rare mild form may have mild delay to development of motor skills and mild eye difficulties.


This condition is caused by mutations in the MCOLN1 gene, which provides instructions for making a protein called mucolipin-1. This protein is located in the membranes of lysosomes and endosomes, compartments within the cell that digest and recycle materials.

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