Bernard-Soulier syndrome caused by a novel GP1BB variant and 22q11.2 deletion

Bernard-Soulier syndrome (BSS) is caused by defects in GP1BA , GP1BB , or GP9 genes. Patients with 22q11.2 deletion syndrome (22q11.2DS) are obligate carriers for BSS because GP1BB resides on chromosome 22q11.2. A 15-month-old girl without bleeding symptoms had giant platelets and thrombocytopenia. Physical findings and macrothrombocytopenia suggested 22q11.2DS, which was confirmed by fluorescence in situ hybridization. Flow-cytometry showed decreased GPIbα on the platelets. A novel variant in GP1BB , p.(Val169_Leu172del), was revealed by gene panel testing. These findings confirmed that she had BSS. This case suggests that any 22q11.2DS patient associated with macrothrombocytopenia should be further investigated for the presence of BSS.