Mucolipidosis IV: A milder form with novel mutations and serial MRI findings

Background Mucolipidosis IV (MLIV; OMIM #252650) is an autosomal recessive lysosomal storage disorder, frequently observed in the Ashkenazi Jewish population. MLIV typically results in intellectual disability, corneal opacities, and delayed motor milestones during infancy, with a relatively static course. To date, reports of MLIV in other ethnic groups have been sparse. Patient The present study is a case report of a 9-year-old Japanese boy, diagnosed via whole-exome sequencing, with compound heterozygous mutations of MCOLN1 (OMIM^*605248): c.410T>C (p.Leu137Pro) and c.802_803delAG (p.Ser268Trpfs*17). Although his clinical course was mild (due to a lack of corneal clouding), other relevant features were present. These included strabismus, white matter signal abnormalities, and a hypoplastic corpus callosum at 2 years of age. After a molecular diagnosis, a markedly elevated serum gastrin level (which is also common in MLIV) was confirmed. Discussion The present results suggest that MLIV could be added as a differential diagnosis for white matter disorders, regardless of ethnicity. Beyond neurological or ophthalmologic findings, serum gastrin could be a useful diagnostic marker for MLIV.