Mucolipidosis Type IV
Mucolipidosis type IV (MLIV) is a very rare inherited disorder that affects how cells break down and recycle materials. It is caused by harmful changes in the MCOLN1 gene, which disrupts lysosomal function. Children with MLIV typically show early developmental delay, weak muscle tone, severe vision problems, and gastrointestinal difficulties. This case report describes a 10‑year‑old boy from Bahrain, representing the first genetically confirmed MLIV case in the country. From infancy, he showed global developmental delay, hypotonia, and progressive visual loss. MRI scans revealed delayed myelination and thinning of the corpus callosum, consistent with MLIV. A key unusual finding was persistently elevated creatine kinase (CK), with levels sometimes exceeding 7,000 U/L. This is not typically seen in MLIV, so the case and hyperCKemia helps expand the phenotypic spectrum of MLIV indicating a possible secondary myopathic involvement.The child also experienced severe gastroesophageal reflux, recurrent infections, anaemia, and malnutrition. Genetic testing confirmed a homozygous MCOLN1 variant. This case highlights that elevated CK does not rule out MLIV, especially in non‑Ashkenazi populations, and emphasises the need for greater awareness and genetic testing in under‑recognized regions.