Reduced levels of tissue plasminogen activator and plasminogen activator inhibitor in plasma of patients with familial amyloidotic polyneuropathy.

Tissue plasminogen activator (tPA) antigen levels and plasminogen activator inhibitor (PAI) activity were measured in the plasma from 23 patients with familial amyloidotic polyneuropathy. Both tPA levels and PAI activity were reduced to about half normal, even when the effects of patient age and body mass index were taken into account. There were higher mean tPA levels and PAI activity in patients with mild disability than in those with moderate or severe disability, but these differences were not statistically significant. There were normal tPA levels after venous occlusion of the upper arm, indicating a normal capacity of vascular endothelium to release tPA. This is the first reported disorder with reduced rather than increased basal tPA and PAI levels. The pathogenetic and clinical significances of these disturbances so far remain obscure.