The mucopolysaccharidoses are a group of inherited disorders of lysoso
mal storage of glycosaminoglycans. Among them, mucopolysaccharidosis (
MPS) type II (Hunter's syndrome), caused by a deficiency in iduronate
sulfatase, is the only one inherited in an X-linked recessive manner.
We describe 12 Hunter's syndrome patients and seven carriers, with pre
cise analysis of glycosaminoglycan content in urine and iduronate sulf
atase activity in cultured fibroblasts and plasma. Their ages at the t
ime of diagnosis ranged from 1 year 10 months to 11 years (mean 4.3 yr
). The delay in diagnosis tvas from 1 month to 5 years (mean 2.1 yr) a
fter the initial presentation. The most frequent initial complaints of
the patients were delayed developmental milestones (75%) and speech (
67%), although all patients were found to have coarsening of facial fe
atures at diagnosis. The difficulties in disease recognition allowed d
isease recurrence in four of the 11 families. Prompt clinical suspicio
n and referral will be important in genetic counseling for MPS type II
and its management, if definitive therapy becomes available.