Mary K. Bennett, Timothy F. Osborne and co-authors nailed it:

»Although the existence of gene families and overlapping mRNAs in higher eukaryotes has been known since the 1970s, the extensive clusters of highly related genes and the almost ubiquitous nature of alternative mRNA processing was not fully realized until the sequence of the human genome was reported 7 years ago. The sequencing of genomes from several other species has confirmed this as a basic feature of all complex eukaryotic organisms. Thus, a major goal now is to define precisely the unique and common roles for the different proteins produced from overlapping transcripts and for closely related proteins in the same family. This is complicated when the proteins are co-expressed in the same cells and function as dimers/multimers in which the individual molecules can form homo- or heteromers as in the case of the mammalian SREBPs.« [Bennett et al. Selective binding of sterol regulatory element-binding protein isoforms and co-regulatory proteins to promoters for lipid metabolic genes in liver. J Biol Chem. 2008 Jun 6;283(23):15628-37.]

2 decades ago, Nobel Laureates Goldstein & Brown discovered SREBPs (SREBP1a, SREBP1c and SREBP2) as key transcriptional regulators of lipid metabolism. However, until January 2016, one year ago, the only "synonyms" for the SREBF1 gene were SREBP1, bHLHd1 and SREBP-1c (provided by NCBI and HGNC). SREBP1a could not be found! This “mistake” was corrected in February 2016, after I have mentioned it. See here: NCBI and HGNC.

Not only SREBP1c, also SREBP1a is a transcript of SREBF1 and SREBP-1c is NOT a synonym for SREBP1a.