Table 2.

Clinical and molecular features mucopolysaccharidosis subtypes.

Type	Subtype	Eponym	Defective Enzyme	Accumulated GAG	Gene Locus	Inheritance	Corneal Clouding	Glaucoma	Optic Neuropathy
I	IH	Hurler	α-L-Iduronidase	HS, DS	4p16.3	AR	+ → +++ 6 months–1.1 years	+/++ 1 year	+/++ 17 years
	I H/S	Hurler-Scheie	α-L-Iduronidase	HS, DS	4p16.3	AR	+/++ 4.4 years	++ 1 year	++ 17 years
	IS	Scheie	α-L-Iduronidase	HS, DS	4p16.3	AR	+ → +++ 24 months–10.5 years	+/++ 1 year	+/++ 17 years
II		Hunter	Iduronate-2-sulfatase	HS, DS	Xq28	XL recessive	Clear/+	+ 7.5 years	None → ++ 33 years
III	A	Sanfilippo A	Heparan-N-sulfatase	HS	17q25.3	AR	+	+	+
	B	Sanfilippo B	α-N-acetylglucosaminidase	HS	17q21	AR	+	+	+
	C	Sanfilippo C	α-glucosaminidase-acetyltranferase	HS	8p11.1	AR	+	+	+
	D	Sanfilippo D	N-acetylglucosamine-6-sulfatase	HS	12q14	AR	+ 8 years	+	+
IV	A	Morquino A	N-acetylgalactosamine-6-sulfatase	KS	16q24	AR	+ 11 years	+ 7.8 years	None → +
	B	Morquino B	β-galactosidase	KS	16q24	AR	+ 11 years	+ 7.8 years	None → +
VI		Maroteaux-Lamy	N-acetylgalactosamine-4-sulfatase	DS	5q12	AR	+++ 7 years	++ 3 years	None → ++ 26 years
VII		Sly	β-D-glucuronidase	HS, DS, KS	7q22	AR	+/++ 15 years	++	None → ++
IX		Natowicz	Hyaluronidase	CS	3p21.2–3	AR	unknown	unknown	unknown

GAG: glycosaminoglycan, DS: dermatan sulfate, KS: keratan sulphate, CS: chondroitin sulphate, AR: autosomal recessive, XL: X-linked.