1. the first affected individual in a family to be studied genetically
Usage: medical; genetics

Examples

• The propositus was a 25-year-old male with symptoms of the inherited disorder.
• Researchers traced the genetic mutation through the propositus and his relatives.
• The family pedigree was constructed starting with the propositus as the reference point.
• Medical geneticists identified the propositus during routine screening.
• The propositus showed clear signs of the autosomal recessive condition.