Genetic predisposition to vaccine-induced immune thrombotic thrombocytopenia: is there a family link?

Background: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare life-threatening thrombotic reaction to COVID-19 vaccines. Case description: Two young male first cousins, with a family history of idiopathic thrombocytopenic purpura, developed VITT after the Ad26.COV2.S vaccine. Both had a favourable clinical and analytical outcome. We investigated the genetic factors that could be associated with a genetic predisposition to VITT. Conclusions: There are no published cases where the VITT patients were relatives. The genetic study did not reveal any likely pathogenic variants, although the prevalent polymorphism c.497A>G (p.(His166Arg)) in the FCGR2A gene was found in a homozygous state. More studies are required to better understand VITT’s pathophysiology and any underlying genetic predispositions.