Elevated Creatine Kinase in Mucolipidosis Type IV: Investigating an Atypical Manifestation and Its Clinical Complications.

Mucolipidosis type IV (MLIV) is a rare autosomal recessive lysosomal storage disorder caused by pathogenic variants in the MCOLN1 gene on chromosome 19. It is characterized by neurodevelopmental delay, progressive visual impairment, and gastrointestinal abnormalities. Here, we report a 10-year-old boy from Bahrain with MLIV who presented with global developmental delay, spastic quadriparesis, severe visual impairment, gastrointestinal manifestations, and persistent elevation of creatine kinase (CK). Serial brain MRI demonstrated delayed myelination, corpus callosum thinning, and periventricular leukomalacia. Diagnosis was confirmed by whole-exome sequencing, identifying a homozygous MCOLN1 variant. Management was supportive, including nutritional optimization, iron supplementation, intermittent blood transfusions, and multidisciplinary follow-up. This case expands the phenotypic spectrum of MLIV by highlighting persistent hyperCKemia, supporting possible secondary myopathic involvement, and emphasizing that elevated CK does not exclude MLIV in non-Ashkenazi populations.