Absence of active cutaneous vasodilation associated with congenital absence of sweat glands in humans.

In the rare syndrome, hereditary anhidrotic ectodermal dysplasia (AED), sweat glands are congenitally absent. Assuming normal vasculature and normal central mechanisms, presence or absence of active cutaneous vasodilation (AVD) in hyperthermic subjects with AED critically tests the hypothesis that AVD is a consequence of sudomotor activity. Three men with full expression of the syndrome and a woman who is mosaic were heated in water-perfused suits until oral temperature was 1.4-1.7 degrees C above control. The men showed no sweat gland imprints on iodine-treated paper nor significant elevation in forearm blood flow (FBF, determined plethysmographically). In the woman, we observed sweat gland activity, approximately 9 and 22 glands/cm2, on the right and left side, respectively, and vasodilation, slight on the right and more on the left. Cutaneous vasoconstriction in response to negative pressure applied to the lower body was observed (3 subjects) and local FBF increased in response to local heating (2 subjects). Therefore, in AED, with apparently normal cutaneous vasculature and sympathetic innervation, AVD is absent as well as sweat glands.