A mother and daughter with the p.R443X mutation of mucopolysaccharidosis type II: Genotype and phenotype analysis.

Mucopolysaccharidosis type II (Hunter syndrome) is a lysosomal storage disease caused by a deficiency of iduronate-2-sulfatase. Most reported patients are males because of X-linked recessive inheritance pattern. Only a few female patients with Hunter syndrome have been reported, and there is no prior report of offspring from a patient with Hunter syndrome. In this report, we describe a woman with mild manifestations of Hunter syndrome who gave birth to a daughter. Both the mother and daughter carried the p.R443X mutation in exon 9 of the ID2S gene. Iduronate-2-sulfatase activity in the mother was as low as that found in male Hunter syndrome patients, but it was in the low-normal range in her daughter. Unlike her mother, the daughter did not show any physical signs of Hunter syndrome, and urinary excretion of glycosaminoglycan was within normal range. However, she had severe pulmonary vein stenosis with pulmonary hypertension and a large atrial septal defect and died at 11 months of age.