Abstract
Five families (three English, one Irish, one West Indian) contained eleven members with sarcoidosis, nine of whom have been investigated and followed. Their multisystem involvement and course was similar to that of other patients attending the Sarcoidosis Clinic at the Royal Northern Hospital. There were three brother-sister and two mother-offspring relations; it was not observed in a father-offspring relationship. It is noted that the course of one sister was considerably worse than that of her brother. The evidence suggests a recessive mode of inheritance for sarcoidosis susceptibility. Four other families are reported on in an Addendum.