Mucolipidosis type IV

Mucolipidosis type IV (ML IV), also known as Berman syndrome or sialolipidosis, is a rare autosomal recessive lysosomal storage disorder caused by mutations in the MCOLN1 gene, which encodes the transient receptor potential channel mucolipin-1 (TRPML1). This protein functions as a cation channel in lysosomes and endosomes, and its deficiency leads to the accumulation of lipids and mucopolysaccharides within cells throughout the body. The disease is particularly prevalent among individuals of Ashkenazi Jewish descent, where the carrier frequency is estimated at approximately 1 in 100. Mucolipidosis type IV typically presents in the first year of life with psychomotor delay, severe intellectual disability, and progressive visual impairment. Corneal clouding is a hallmark feature, often present from early infancy, and retinal degeneration develops over time, frequently leading to blindness. Most affected individuals never achieve independent ambulation or meaningful speech. Hypotonia in infancy may evolve into spasticity. A distinctive feature of ML IV compared to other mucolipidoses is the absence of skeletal abnormalities (dysostosis multiplex) and organomegaly, which helps distinguish it clinically. Achlorhydria (absence of gastric acid secretion) with resulting iron-deficiency anemia and elevated blood gastrin levels is a characteristic finding. Neurodegeneration is slowly progressive, and most patients survive into adulthood, though with severe disability. There is currently no cure or disease-specific treatment for mucolipidosis type IV. Management is supportive and multidisciplinary, including ophthalmologic care, physical and occupational therapy, nutritional support, and iron supplementation for anemia. Research into potential therapies, including gene therapy approaches, is ongoing but remains in early stages.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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