Mucolipidosis type IV is a unique autosomal recessive progressive neurodegenerative disorder of unknown etiology. There is minimal facial dysmorphism and absence of organomegaly. Most patients reported are of Ashkenazi Jewish descent.
We present two patients from northern Newfoundland with significant developmental and speech delay, ataxia, corneal clouding, and absence of organomegaly. The skin biopsy was significant for the presence of lamellar inclusions which exhibited autofluorescence characteristic of Mucolipidosis IV cells. Cranial MRI showed changes in signal intensity consistent with increased ferritin deposition in the thalamus in one of the patients (female) but was normal in the second (male). Both the patients did not show any changes in the white matter, nor hypoplasia of the corpus callosum. Both patients had elevated serum gastrin levels, 936 and 332 pmol/L (0-43 pmol/L) respectively. The finding of high serum gastrin in patients with Mucolipidosis IV has been recently reported by Schiffmann R et al (Proc Natl Acad Sci USA 1998 Feb 3;95(3): 1207-12). This finding in combination with the characteristic skin biopsy findings can be diagnostic for this disorder.
Our patients belong to the same geographical area. They are not of Ashkenazi Jewish ancestry. Both the patients exhibit a milder course without neurological deterioration. They lack the typical cranial MRI findings of cerebellar atrophy and hypoplastic corpus callosum reported recently.
With the availability of reliable diagnostic testing, the pathogenesis and etiology of this poorly understood condition will likely be delineated in the future.
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Prasad, C., Buckley, D., Pushpanathan, C. et al. Experience with Mucolipidosis Type IV in Newfoundland. Genet Med 1, 51 (1999). https://doi.org/10.1097/00125817-199901000-00040