Morquio syndrome

Morquio syndrome is an autosomal recessive mucopolysaccharidosis (MPS), type IV.

Epidemiology

Incidence estimated at ~1:40,000.

Clinical presentation

Many cases present at ~2 years of age and have normal intelligence. Clinical features:

• severe dwarfism (<4 foot)
• joint laxity
• corneal opacification/clouding
• lymphadenopathy
• progressive deafness
• spinal kyphoscoliosis
• prominent mandible and lower face 
• short neck

Pathology

It results from an excess of keratan sulphate from a deficit in its degradation pathway. Keratan sulphate accumulates in various tissues inclusive of cartilage, the nucleus pulposus of the intervertebral disc and cornea.

Radiographic features

Plain radiography/CTradiograph / CT

Axial manifestations

• platyspondyly
• hypoplasia of odontoid peg
• atlantoaxial subluxation
• os odontoideum
• anterior central vertebral body beaking
• round vertebral bodies 
• coxa valga
• goblet shaped flared iliac wings, increased acetabular angles and constricted iliac bone base

Calvarial manifestations

• hypertelorism
• dolichocephaly

Peripheral musculoskeletal manifestations

• metaphyseal flaring in long bones
• multiple epiphyseal centres
• wide metacarpals with proximal pointing, irregular carpal bones 
• short and wide tubular bones
• proximal point of index to little finger metacarpal
• flattened femoral epiphyses; risk of lateral subluxation and dislocation
• coxa valga
• genu valgum

Thoracic manifestations

• anterior sternal bowing, increased AP chest diameter, wide ribs

Echocardiography

• late onset aortic regurgitation

Treatment and Prognosis

Life expectancy ranges between 30-40 years. The most common cause of death is cervical myelopathy from C2 abnormality. Patients are also particularly vulnerable to respiratory infection.

History and etymology

Named after Luis Morquio, an Uruguayan paediatrician (1867-1935) ⁵.