Familial sarcoidosis with multiple occurrences in eleven families: a possible mechanism of inheritance.

Among 80 Black patients with sarcoidosis, 11 families were identified as containing multiple cases. Monogenic modes of inheritance were reasonably excluded by informal inspection of pedigree patterns and by poor fit of corrected ratios within sibships to the expected ratio for all sibships at risk. The observed familial distribution conforms in several respects to properties that are descriptive of multigenic traits. Additionally, heritability based only on female probands was estimated to be between 60% and 70%. A larger sample size should permit analysis of additional multigenic properties.