Differences in genetic and epigenetic alterations between von Hippel-Lindau disease-related and sporadic hemangioblastomas of the central nervous system

Background: Although inactivation of the von Hippel-Lindau gene (VHL), located on chromosome 3p25, is considered to be a major cause of hemangioblastomas (HBs), the incidence of biallelic inactivation of VHL is reportedly low. The aim of this study was to determine the prevalence of VHL alterations in HBs, as well as to identify additional molecular aberrations.

Methods: Genetic and epigenetic alterations were comprehensively and comparatively analyzed in 11 VHL-related and 21 sporadic HBs.

Results: VHL alterations detected by sequencing and multiplex ligation-dependent probe amplification (MLPA) analysis were more frequent in VHL-related HBs than in sporadic HBs (100% vs 62%; P = 0.029). VHL alterations were found only in 4 sporadic HBs by direct sequencing; however, targeted deep sequencing detected 9 additional alterations. Loss of heterozygosity (LOH) on chromosome 3 was found in 64% and 57% of VHL-related and sporadic HBs, respectively, by single nucleotide polymorphism (SNP) array analysis. Among 19 tumors with chromosome 3 LOH, 5 were classified as copy-neutral LOH. VHL promoter hypermethylation was detected only in sporadic HBs (33%), indicating that epigenetic suppression of VHL is a common mechanism in sporadic HBs. The rate of biallelic VHL inactivation among VHL-related and sporadic HBs was 64% and 52%, respectively. LOH on either chromosome 6 or 10 was detected only in sporadic HBs (43%).

Conclusion: Although biallelic inactivation of VHL is a dominant mechanistic cause of the pathogenesis of HB, other unknown mechanisms may also be involved, and such mechanisms may be different between VHL-related and sporadic HB.