Molecular basis of Bernard-Soulier syndrome in 27 patients from India

Bernard-Soulier syndrome (BSS) is an extremely rare (1:1 million) bleeding disorder of platelet adhesion, caused by defects in the glycoprotein (GP)Ib/IX/V complex.

The diagnosis in 27 patients was based on low platelet count, presence of giant platelets and aggregometry studies. Flow cytometry to assess the surface GPIb/IX/V complex showed reduced (7.7-57%) expression. gDNA was screened for mutations in the GPIBA, GPIBB, GP9 genes using PCR-conformation sensitive gel electrophoresis (CSGE).

Thirteen different disease-causing mutations, including missense (54%), frameshifts (38%) and nonsense (8%) mutations, were identified in 27 patients. Eleven of them were novel including five novel frameshifts (GPIbα: p.Gln97_98fsX113, p.Pro402_403fsX52; GPIbβ: p.Arg17fsX14; GPIX: p.Gly24fsX43, p. Pro130fs, a nonsense mutation (GPIX, p.94, Gln>X) and five novel missense mutations (GPIbα: p.492, Tyr>His; GPIbβ: p.65, Pro>Arg, p.129, Gln>His, p.132, Leu>Pro; GPIX: p.55, Phe>Cys). Interestingly, four common mutations, Cys8Arg (n = 6) and Phe55Ser (n = 2), Phe55Cys (n = 2) in GPIX and a novel 22-bp deletion in the GPIBB gene predicting p.Arg17fsX 14 (n = 10) were seen in 20 patients.

The molecular data presented here is the largest series of BSS patients to be reported so far, adding significantly to the mutation database of this condition and also useful for its genetic diagnosis in India.