Germline mutations in the spindle assembly checkpoint genes BUB1 and BUB3 are infrequent in familial colorectal cancer and polyposis
Germline mutations in BUB1 and BUB3 have been reported to increase the risk of developing colorectal cancer (CRC) at young age, in presence of variegated aneuploidy and reminiscent dysmorphic traits of mosaic variegated aneuploidy syndrome. We performed a mutational analysis of BUB1 and BUB3 in 456 uncharacterized mismatch repair-proficient hereditary non-polyposis CRC families and 88 polyposis cases. Four novel or rare germline variants, one splice-site and three missense, were identified in four families. Neither variegated aneuploidy nor dysmorphic traits were observed in carriers. Evident functional effects in the heterozygous form were observed for c.1965-1G>A, but not for c.2296G>A (p.E766K), in spite of the positive co-segregation in the family. BUB1 c.2473C>T (p.P825S) and BUB3 c.77C>T (p.T26I) remained as variants of uncertain significance. As of today, the rarity of functionally relevant mutations identified in familial and/or early onset series does not support the inclusion of BUB1 and BUB3 testing in routine genetic diagnostics of familial CRC. ; his work was supported by the Spanish Ministry of Economy and Competitiveness, co-funded by FEDER funds – a way to build Europe – (grants SAF2016 – 80888-R to LValle, SAF2015 – 68016-R to GC and MP, and SAF2013 – 45836-R to XSP]; Carlos III National Health Institute [PI16/00563 to CL and CIBER- ONC]; the Government of Catalonia [ Pla estratègic de recerca i innovació en salut (PERIS) and 2014SGR338]; the Scientific Foundation Asociación Española Contra el Cáncer ; and EU COST Action BM1206. PM holds a Juan de la Cierva postdoc- toral fellowship from the Spanish Ministry of Economy and Competitiveness, and RMdV, a Dutch Cancer Society (KWF) Fellowship (KUN14–666 ; Sí