I am trying to use the 'readGVF' function but it seems to be inexistent.
 

> library("cnvGSAdata")
> library(cnvGSA)
> readGVF()
Error: could not find function "readGVF"
> sessionInfo()
R version 3.2.2 (2015-08-14)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=C                  LC_COLLATE=C
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats4    parallel  stats     graphics  grDevices utils     datasets
[8] methods   base

other attached packages:
 [1] cnvGSAdata_1.6.0      cnvGSA_1.14.0         splitstackshape_1.4.2
 [4] data.table_1.9.6      GenomicRanges_1.22.0  GenomeInfoDb_1.6.0
 [7] IRanges_2.4.0         S4Vectors_0.8.0       BiocGenerics_0.16.0
[10] doParallel_1.0.10     iterators_1.0.8       foreach_1.4.3
[13] brglm_0.5-9           profileModel_0.5-9    BiocInstaller_1.20.0

loaded via a namespace (and not attached):
[1] codetools_0.2-14 chron_2.3-47     zlibbioc_1.16.0  XVector_0.10.0
[5] tools_3.2.2

Any idea why?

Can you say what package you expect that function to be in? There is no indication that I can see that the function is part of cnvGSA, and a search of the entire BioC subversion using Itoshi Nikaido's awesome search page doesn't come up with that function name in any BioC package.