Table 2.

Earliest time for manifestations in patients with MPS IH and MPS IIA.

	MPS IH	MPS IIA
Cognitive development	Progressive cognitive decline beginning at age 6–15 months [18,39,176,177,178]	Normal until age 3–4 years, followed by plateau and rapid decline [4,179]
Coarse facial features	6–12 months [18]	2–4 years [23]
Hearing loss	6–12 months [20]	4 years [32]
Cardiac valve disease	1 year [18]	6 years [23]
Kyphosis	1 year [18]	6 years [23,24]
Axial growth	Normal until age 3 years	Normal to accelerated until age 5–6 years [23,180]
Average age at diagnosis	1 year [18]	3–4 years [23,24,180,181]