Recommended rules for symbolization
1. In naming hereditary factors, the use of languages of higher internationality should be given preference.
2. Symbols of hereditary factors, derived from their original names, should be written in Roman letters of distinctive type, preferably in italics, and be as short as possible.
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Examples:
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| Drosophila: | rudimentary r |
| Mouse: | kreisler kr |
| Neurospora: | p-aminobenzoicless pab |
| Maize: | virescent v |
3. Whenever unambiguous, the name and symbol of a dominant begin with a capital letter and those of a recessive with a small letter.
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Examples:
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| Man and rabbit: | Pelger Pg |
| Silkworm: | elongate e |
| Wheat: | Blue kernel Bk |
| Drosophila: | yellow y |
4. Literal or numeral superscripts are used to represent the different members of an allelic series.
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Examples:
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| Drosophila: | vq, vg2, vg40b, vga, vgni, etc. (vestigial series) |
| Man: | I0, IA1, IA2, IB, etc. (Isoagglutinogens of the ABO blood group series) |
| Mouse: | ci, cch, ce, c, etc. (colour or albino series) |
5. Standard or wild type alleles are designated by gene symbols with + as a superscript or by + with the gene symbol as a superscript. In formulae the + alone may be used.
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Examples:
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| Drososhila: | vg+, +vg or + |
6. Two or more genes having phenotypically similar effects are desiguated by a common basic symbol. Non-allelic loci (mimics, polymeric genes, etc.) are distinguished by an additional letter or Arabic numeral either on the same line after a hyphen or as a subscript. Alleles of independent mutational origin may be indicated by a superscript.
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7. Inhibitors, suppressors and enhancers are designated by the symbols I, Su and En, or by i, su and en if they are recessive, followed by a hyphen and the symbol of the allele affected.
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Examples:
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| Fowl: | I-C, inhibitor of colour |
| Galeopsis: | I-R, inhibitor of colour |
| Pharbitis: | su-dy, suppressor of dragonfly |
| Silkworm: | En-odm, enhancer of oily mottled |
8. Whenever convenient, lethals should be designated by the letter l or L, and sterility and incompatability genes by s or S.
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Examples:
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| Drosophila: | letal-translucida l-tr |
| bobbed-lethal bbl | |
9. Linkage groups and corresponding chromosomes are preferably designated by Arabic numerals.
10. The letters X and Y are recommended to designate the sex chromosomes.
11. Genic formulae are written as fractions with the maternal alleles given first or above. Each fraction corresponds to a single linkage group. Different linkage groups written in numerical sequence are separated by semicolons. Symbols of unlocated genes are placed within parentheses at the end of the formula. In euploids and aneuploids the gene symbols are repeated as many times as there are homologous loci.
12. Chromosomal aberrations should be indicated by the abbreviations: Df for deficiency, Dp for duplication, In for inversion, T translocation, Tp for transposition.
13. The zygotic number of chromosomes is indicated by 2n, the gametic number by n and the basic number by x.
14. Symbols of extra-chromosomal factors should be enclosed within brackets and precede the genic formulae.