Morquio syndrome (Mucopolysaccharidosis type IV) — overview and management

Clinical features and course

Symptoms typically appear in early childhood and include short stature, abnormal spine curvature, a narrow chest, joint laxity, and distinctive skeletal deformities of the pelvis, legs and hands. Other common findings are breathing difficulties, frequent ear and airway infections, corneal clouding or vision problems, dental abnormalities and heart valve disease. Cognitive development is usually normal, but physical disability can progress over time and require multidisciplinary care.

Cause and diagnosis

Morquio syndrome is inherited in an autosomal recessive pattern and is divided into subtypes based on the deficient enzyme. MPS IVA results from deficiency of an enzyme needed to degrade specific glycosaminoglycans; MPS IVB has a different enzymatic defect. Diagnosis typically involves urine tests for glycosaminoglycan fragments, enzyme activity assays and confirmatory genetic testing. Radiographs and other imaging show characteristic skeletal changes that help guide evaluation.

Treatment and management

Treatment emphasizes symptom control, preserving function and slowing tissue accumulation. A disease‑specific approach is enzyme replacement therapy, in which patients receive a synthetic form of the missing enzyme to reduce storage material and improve some clinical measures. Supportive care includes orthopedic surgery, respiratory support, hearing and vision care, dental treatment and individualized rehabilitation. Long‑term follow‑up by a multidisciplinary team is essential.

History, research and prognosis

The disorder was first described in the early 20th century and later classified among the mucopolysaccharidoses as biochemical and genetic techniques improved. Research continues into improved enzyme preparations, delivery systems that better reach bone and cartilage, and gene‑based approaches. Prognosis varies widely depending on severity, subtype and access to supportive and disease‑modifying therapies.

Notable facts

• Often inherited in an autosomal recessive manner, so families may benefit from genetic counseling.
• Physical symptoms dominate; intelligence is commonly preserved.
• Enzyme therapy targets the underlying enzyme deficiency (for example, the enzyme implicated in MPS IVA is frequently the focus of treatment studies; see the missing enzyme).
• Care requires coordination among pediatricians, geneticists, orthopedists, cardiologists and other specialists.