[Genetic markers and thrombin reaction in a family of Bernard-Soulier syndrome].

A family with Bernard-Soulier syndrome (BSS) was investigated with reference to the genetic markers and thrombin reactions. The proband was a 24-year-old man with a life-long history of epistaxis and gingival bleeding. His parents were first cousins; furthermore, his father was born to parents of second cousins. His father also had bleeding tendency and was also diagnosed as having BSS. However, his mother and elder brother were normal. Genetic marker analysis among the family members suggested that the 16th chromosome was associated with the development of BSS, because only the haptoglobin genotype coded on the 16th chromosome was the marker in both the proband and his father. In addition, they both exhibited decreased thrombin-induced platelet aggregation at a low dose, but an almost normal reaction at a high dose of thrombin.