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Inborn error of metabolism characterized by the deficiency of one of 10 specific lysosomal enzymes, resulting in an inability to metabolize complex carbohydrates (mucopolysaccharides) into simpler molecules. It exists in two forms: Morquio syndromes A and B are caused by a deficiency in the enzyme N-acetyl-galactosamine-6-sulfatase and β-galactosidase, respectively. May be detected as early as 18 months to 2 years. The skeletal abnormalities may include macrocephaly, a broad mouth, prominent cheekbones, an unusually small nose, short necks, short barrel chests, disproportionately long arms, enlarged and possibly hyperextensible wrists, stubby hands, and “knock knees.” The joint laxity and bony abnormalities of the spine can result in life-threatening spinal cord compression. The presence of a thoracic kyphoscoliosis may contribute to spinal cord ischemia risk during positioning. Aortic regurgitation and deafness have been reported.

Morquio syndrome

Short stature and marked varus gonarthrosis (knock knees) in a patient with Morquio syndrome.

Morquio syndrome

Characteristic facies with mild coarsening, midface hypoplasia, and macroglossia in a young boy with Morquio syndrome.

Mucopolysaccharidosis Type IV; Morquio-Silfverskiöld Syndrome Morquio-Brailsford Syndrome; Morquio-Ullrich Syndrome; Atypical Chondrodystrophy; Dysotosis Enchondralis Metaepiphysaria; Eccentrochondrodysplasia; Eccentro-Osteochondrodysplasia; Familial Osseous Dystrophy; Hereditary Chondrodysplasia; Hereditary Osteochondrodystrophy; Hereditary Polytopic Enchondral Dysostosis; Keratansulfaturia; KS Mucopolysaccharidosis; Osteochondrodystrophia Deformans; Osteochondrodystrophy; Spondyloepiphyseal Dysplasia; Silfverskiöld Syndrome.

Type A: Morquio Syndrome A; Galactosamine-4-Sulfatase (GALNS) Deficiency

Type B: Morquio Syndrome B; Morquio-Like Syndrome; β-Galactosidase Deficiency

First described by L. Morquio, a Uruguayan pediatrician, in 1929 while living in Montevideo, Uruguay. He observed the disease in four sibs in a Swedish family. It is also suggested that J. F. Brailsford, a British pediatrician from Birmingham, England, simultaneously described the disease.

It is estimated between 1:40,000 and less than 1:200,000 live births. In the United States, it is estimated that 1 in 25,000 births results in some form of mucopolysacchidosis.

Autosomal recessive.

Deficiency of N-acetylgalactosamine-6-sulfate sulfatase (type A) or β-galactosidase (type B) leads to storage of keratan sulfate in tissues.

Two types lead to identical phenotype. Keratan sulfate in urine. Specific enzyme assay diagnostic.

Affected children have normal mental development but severe physical manifestations. Short trunk, lax joints, short neck, corneal clouding, midface hypoplasia with mild coarsening of the facies. Progressive kyphoscoliosis leads to cardiorespiratory failure with death from cor pulmonale in third or fourth decade. May have aortic insufficiency. Hypoplasia of the odontoid is common, causing atlantoaxial subluxation and cord compression. Platyspondyly. Tracheal collapse with flexion of the neck reported. Very thin teeth enamel in type A. Progressive hearing loss.

Assess cardiorespiratory status carefully and obtain appropriate investigations, for example, echocardiogram. Assess airway carefully. Obtain radiographs of cervical spine. Sleep apnea syndrome caused by hypertrophied tonsils ...

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