The person in a genetic investigation who exhibits the diagnosis or trait that is of interest to the investigator.
The person about whom medical and genetic information is being gathered for the construction of a family pedigree during genetic counseling; also called propositus (female: proposita) or index case.
The initial subject presenting a mental or physical disorder and who causes a study of his or her heredity in order to determine if other members of the family have had the same disease or carry it.