A Narrative Review of Morquio Syndrome: Mucopolysaccharidosis (MPS) Type IV

Abstract

Background: Morquio Syndrome or Mucopolysaccharidosis Type IV (MPS IV) is a rare inherited metabolic disorder characterized by the deficiency of certain lysosomal enzymes involved in the breakdown of mucopolysaccharides. The deficiency results in proteoglycan accumulation, particularly keratan sulfate in various tissues in the body. Morquio Syndrome is classified into two subtypes: Morquio A and Morquio B, which are distinguished by the specific enzyme deficiency involved, with Morquio A being more prevalent. Morquio Syndrome commonly affects the eyes with 46.7% of diagnosed patients experiencing ocular symptoms related to the disorder. Objective: To perform a comprehensive review of the existing literature and summarize the ophthalmological manifestations of Morquio Syndrome. Methods: A methodical literature search was conducted, including papers with abstracts discussing ophthalmology or ocular pathology of “Mucopolysaccharidosis Type IV” or ” Morquio Syndrome.” Twelve relevant articles met the inclusion criteria and were included in the review. Seven of the articles consisted of case reports, collectively reporting on forty-one patients with Morquio Syndrome, primarily Morquio A. The outcome of the narrative review is an overview of the existing literature on ocular presentations of Morquio Syndrome and a summary of case report findings. Results: Forty-one different patients were identified from the included case reports, and forty patients were included as they presented with ocular pathology related to Morquio Syndrome. Corneal opacification was the most common presentation where twenty-seven patients had significant corneal opacification and seven patients had slight corneal opacification. Small, gray, spherical, dust-like opacities that dispersed among the stroma were most commonly seen in cases with corneal opacification. Other ocular presentations included decreased visual acuity, astigmatism, lens opacities, and glaucoma. Conclusion: Morquio syndrome, a rare genetic disorder, exhibits multiple ocular symptoms, with corneal opacification being the most common. While most research has concentrated on Morquio A, the more severe subtype, there's limited information on Morquio B, highlighting a need for more comparative studies. As the syndrome remains incurable, exploring new treatment avenues and understanding the reasons behind these ocular manifestations can significantly improve the quality of life for Morquio patients.