A female child of healthy, unrelated parents presented at 12 months of age with 
a history of moderately severe developmental delay, macrocephaly, dysmorphic 
facies, hypotonia, hepatosplenomegaly, mild generalized dysostosis multiplex, 
mucopolysacchariduria (dermatan and heparan sulfates), and Alder-Reilly bodies 
in peripheral blood leukocytes. Iduronate sulfatase activity in plasma was 
markedly depressed: 0.11 units/ml/h (normal, 1.75 +/- 0.56, N = 6). Analyses of 
arylsulfatases A, B, and C, heparan N-sulfatase, alpha-mannosidase, 
beta-mannosidase, beta-glucuronidase, beta-hexosaminidase, beta-galactosidase, 
and alpha-fucosidase activities in plasma, leukocytes, and/or cultured skin 
fibroblasts were all normal. Urinary sulfatide excretion was also within normal 
limits. Karyotypes of peripheral blood leukocytes and cultured skin fibroblasts 
were normal. Serum iduronate sulfatase activities in the parents were in the 
normal range (father, 1.63 units/ml/h; mother, 1.25 units/ml/h). The results of 
analyses of restriction fragment length polymorphisms (RFLP) of DNA from 
cultured skin fibroblasts with the use of probes for loci extending from Xpter 
to Xq28 showed X chromosome heterozygosity and confirmed the paternal origin of 
one of the X chromosomes. Studies on sulfur-35 uptake in mixed fibroblast 
cultures showed cross-correction of [35S]-glycosaminoglycan accumulation between 
cells from the patient and normal cells or cells from a patient with Hurler 
disease; however, there was no cross-correction between cells from the patient 
and those from boys affected with classical Hunter disease. This represents only 
the second confirmed case of Hunter disease reported in a karyotypically normal 
girl.