‘Vertical’ #pleiotropy is when a variant affects a phenotype that has its own downstream effects on another phenotype

‘Horizontal’ pleiotropy is where a variant has multiple independent effects; no phenotype mediates another

Needless terminology! Easily represented in simple #DAGs as chaining and common cause, respectively. #Genetics should avoid making up new terms for simple stuff.

The interesting twist for genetics is #LinkageDisequilibrium because it can masquerade as pleiotropy