Mucolipidosis type IV
General description
Mucolipidosis type IV (MLIV) represents a rare autosomal recessive lysosomal storage disorder that profoundly affects neurodevelopment and visual function through mutation of the MCOLN1 gene coding the TRPML1 channel protein.
Clinical manifestations
The clinical presentation of MLIV typically manifests within the first year of life with severe global developmental delay affecting motor, cognitive, and visual domains. Most patients demonstrate profound psychomotor retardation characterized by delayed achievement of developmental milestones.
Visual impairment represents a prominent and progressive feature of MLIV, encompassing multiple ocular abnormalities including bilateral corneal clouding, retinal degeneration, and optic atrophy.
Gastrointestinal manifestations include constitutive achlorhydria resulting from absence of gastric acid secretion, which leads to secondary elevation of blood gastrin levels and frequently causes iron deficiency anemia.
References
- Frei, K. P., et al. "Mucolipidosis type IV: characteristic MRI findings." Neurology 51.2 (1998): 565-569.
White matter lesion
MRI demonstrates diffuse hyperintensity on T2-weighted images, sparing subcortical white matter.
Corpus callosum abnormality
The corpus callosum demonstrates consistent and characteristic abnormalities in MLIV patients, with hypoplasia representing the most prominent finding across virtually all affected individuals.
Iron deposition
Brain iron accumulation represents another pathognomonic feature of MLIV, with increased ferritin deposition consistently observed in the thalamus and basal ganglia.