Joint contractures in the absence of inflammation may indicate mucopolysaccharidosis

Table 1 MPS Disorders Likely to be Encountered by a Rheumatologist or Orthopedist

	MPS I (Hurler, Hurler-Scheie, Scheie)	MPS II (Hunter)	MPS IV (Morquio)	MPS VI (Maroteaux-Lamy)	MPS VII (Sly syndrome)
Deficient lysosomal enzyme	α-L-iduronidase	Iduronate sulfatase	Galactose 6-sulfatase or β-galactosidase	Arylsulfatase B	β-Glucuronidase
Inheritance	Autosomal recessive	X-linked recessive (most patients are male)	Autosomal recessive	Autosomal recessive	Autosomal recessive
Common clinical manifestations in attenuated patients (can be subtle or severe)
Joint involvement with no inflammation	+	+	+ *	+	+
Dysostosis multiplex	+	+	+ *	+	+
Growth deficits	+	+	+	+	+
Corneal clouding	+	None	+	+	~
History of umbilical and/or inguinal hernia	+	+	+	+	+
Elevated total urinary glycosaminoglycan level^† and/or abnormal glycosaminoglycan profile	+	+	+^§	+	+
Coarse facies	+	+	+	+	+
Carpal tunnel syndrome	+	+	~	+	+
Cardiac valve disease	+	+	+	+	+
Enzyme replacement therapy	Laronidase (Aldurazyme^®)	Idursulfase (Elaprase^®)	In development	Galsulfase (Naglazyme^®)	In development

*MPS IV is characterized by distinctive and severe skeletal dysplasia, dysplastic odontoid process, and joint hyper-extendibility/ligamentous laxity.
^†False negatives can occur with spot screening.
^§Patients with MPS IV typically have an abnormal GAG profile, but total urinary GAG levels can be in the normal range with some methodologies

ISSN: 1546-0096