Morquio Syndrome Type IVA, an Autosomal Recessive Lysosomal Storage Disorder in a 7-year-old Female: A Case Report

Abstract

Mucopolysaccharidosis Type IV (Morquio syndrome) is a rare autosomal recessive lysosomal storage disorder caused by deficiency of N-acetylgalactosamine-6-sulfatase, resulting in progressive accumulation of Glycosaminoglycans (GAG) in multiple tissues. The disorder primarily affects skeletal development and is characterised by short stature, skeletal dysplasia, kyphoscoliosis, pectus carinatum and genu valgum, while intelligence is usually preserved. Diagnosis is established through biochemical and genetic investigations demonstrating elevated levels of keratan sulfate and chondroitin-6-sulfate along with reduced enzyme activity. Management is mainly supportive and involves Enzyme Replacement Therapy (ERT), orthopaedic interventions and multidisciplinary monitoring to improve functional capacity and quality of life. A seven-year-old female child presented with progressive lower limb deformities and inability to walk. Clinical evaluation revealed characteristic skeletal abnormalities with normal cognitive function. A history of third-degree consanguinity and sibling mortality with similar complaints raised suspicion of an inherited metabolic disorder. Enzyme assay confirmed Morquio syndrome Type A. Although ERT was advised, logistic and financial constraints limited its availability. The present case emphasises the importance of early diagnosis, genetic counselling and family screening, particularly in populations with high prevalence of consanguineous marriages, to facilitate timely intervention and improve longterm outcomes.