It it has now lost its subscripts and superscripts and conforms to the limitations of amateur computing and simple text editing. It retains the major advantage of the greater legibility of lower case. The rat has its own nomenclature, mainly followng the mouse, but the first character is capitalised. Almost all other species follow the human nomenclature, except in the HLA locus. The scale of human mapping made it impractical to follow any clear rules, and many loci are named with little other consideration than having a uniquenees unless clearly homologous to the mouse, when the mouse nomenclature was followed but, to add to the confusion, capitalised.
Some journals capitalise all first letters in mice.
The larger mammals follow the human nomenclature, with species-specific names for their MHC loci.such as DLA and HLA for dog and man. These will be recoded MHC throughout, with the shorter segment in those ruminants with an intervening segment ignored, or termed MHC2 - at present only defined in the cow in these data and loci represented in only one pecies included are ignored. The mouse and cow have effectively no short arms. For example human chromosomes 21 and 22 are almost indentical in length on the long arm and the very small short arm is of variable length. Lejeune described what is now known as Down's syndrome as trisomy 21 and when techniques showed this to be demonstrably shorter than 22 the the original numbers were retained.