Familial disorder with increased number of insulin receptors: a new category of insulin receptor abnormality

We found a family in which 6 of 13 family members had extremely high insulin binding to their erythrocytes. The specific binding values of these patients were 3- to 4- fold higher (22.8-28.6% of added [125I]insulin) than normal (mean ± SD, 7.1 ± 0.8%; r = 44). Scatchard analysis revealed that in each patient increased insulin binding was due to increased binding capacity, with little change in affinity. In all patients, reticulocyte counts were within the normal range. From the pedigree analysis, the pattern of inheritance was considered to be autosomal dominant. The propositus was more extensively studied. His mononuclear leukocytes and Triton X-100-solubilized preparations of erythrocyte ghosts also had high (∼3-fold) insulin-binding capacity compared to that of normal subjects. In contrast, the number of ouabain-binding sites and kinetics of sugar transport were normal. From these findings, we propose a new type of inherited abnormality of the insulin receptor.