Vertebrate genes and proteins have names (typically strings of words) and symbols, which are short identifiers (typically 3 to 8 characters). For example, the gene cytotoxic T-lymphocyte-associated protein 4 has the HGNC symbol CTLA4. These symbols are usually, but not always, coined by contraction or acronymic abbreviation of the name. They are pseudo-acronyms, however, in the sense that they are complete identifiers by themselves—short names, essentially. They are synonymous with (rather than standing for) the gene/protein name (or any of its aliases), regardless of whether the initial letters "match". For example, the symbol for the gene v-akt murine thymoma viral oncogene homolog 1, which is AKT1, cannot be said to be an acronym for the name, and neither can any of its various synonyms, which include AKT, PKB, PRKBA, and RAC. Thus, the relationship of a gene symbol to the gene name is functionally the relationship of a nickname to a formal name (both are complete identifiers)—it is not the relationship of an acronym to its expansion. In this sense they are similar to the symbols for units of measurement in the SI system (such as km for the kilometre), in that they can be viewed as true logograms rather than just abbreviations. Sometimes the distinction is academic, but not always. Although it is not wrong to say that "VEGFA" is an acronym standing for "vascular endothelial growth factor A", just as it is not wrong that "km" is an abbreviation for "kilometre", there is more to the formality of symbols than those statements capture.
The root portion of the symbols for a gene family (such as the "SERPIN" root in SERPIN1, SERPIN2, SERPIN3, and so on) is called a root symbol.