The Hunter syndrome in females: is there an autosomal recessive form of iduronate sulfatase deficiency?

Profound iduronate sulfatase deficiency, characteristic of the Hunter syndrome, has been found in cultured fibroblasts, serum, lymphocytes, and tissues of two clinically affected girls. The patients are karyotypically normal and have normal fathers; cloning of the mothers' fibroblasts did not reveal the mosaicism expected of carriers of an X-linked disease. Homozygosity for a previously unsuspected autosomal recessive gene for iduronate sulfatase is considered the most likely explanation, although heterozygosity for the X-linked gene and subsequent selection cannot be completely excluded.