Iduronate sulfatase analysis of hair roots for identification of Hunter syndrome heterozygotes.

Iduronate sulfatase, the enzyme deficient in Hunter syndrome, can be readily measured in individual hair roots. Samples from Hunter syndrome hemizygotes had activities at or near the limits of detection. Samples from two mothers of Hunter syndrome patients, one an obligate heterozygote, had lower average iduronate sulfatase activity than the normal mean, and a significant number of hair roots had activity in the pathognomic range. A third mother showed a normal distribution of enzyme activity, and no hair roots were in the range of those from an affected individual. These results are similar to studies on the distribution of other X-linked enzymes in individual hair root samples from heterozygotes. This suggests that hair root iduronate sulfatase assessment is useful in the detection of Hunter syndrome carrier status, but further refinement of the test system is necessary.