What doesn't make sense here? Questions, comments, and suggestions are welcome.
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The words "heterozygous albino" contain 19 letters. That is a lot of bandwidth, particularly if it must be written over and over when diagramming a cross.
Mendel used letter symbols for several reasons. He lacked words because "heterozygous" and other genetics terms had not been invented. And symbols were simple, clear, and easy to understand. Geneticists have continued to use symbols for much the same reasons.
Various groups of geneticists have agreed on rules for genetic symbols. These rules allow a few alphanumeric characters to indicate whether the gene is normal or mutant, dominant or recessive, allelic or independent, etc. That is quite a load of information to carry, but it can be done.
So far, there is no single set of rules for gene symbols for all species. The rules for the fruit fly are not exactly the same as the rules for the mouse. And the rules for the mouse are not exactly the same as for maize, though there is considerable agreement. As uniformity is desirable, these rules follow the <A HREF="http://www.informatics.jax.org/mgihome/nomen/table.shtml">gene nomenclature for the mouse</A>.
1. Give the mutant a unique name that is reasonably descriptive of the phenotype. Examples: amelanistic, charcoal, striped.
2. Derive the unique one to four letter symbol from the unique mutant name, and italicize the symbol if possible. Alphabet books for young children often start with "a is for apple." In the same way, <I>c</I> is for charcoal. Because <I>c</I> is already used, <I>ca</I> is for caramel.
3. Use lower case letters for all letters symbolizing a recessive mutant. Again, <I>ca</I> is for caramel, a recessive mutant gene.
4. Use an upper case letter for the first letter in the symbol for a dominant or codominant mutant. The symbol <I>T</I> is for tiger, a codominant mutant in the reticulated python.
5. The locus symbol is the same as the symbol given to the first mutant discovered at that locus. The <I>a</I> locus has the <I>a</I> (amelanistic) mutant gene and all its alleles.
6. The wild type allele is symbolized by either the <I>+</I> symbol alone or by the locus symbol with the + symbol as a superscript. The wild type allele at the <I>a</I> locus can be either <I>+</I> (if the useage is obvious) or <I>a<SUP>+</SUP></I> (to make useage absolutely clear).
7. Multiple alleles are symbolized by one or two lower case letters added to the base symbol as a superscript. In the mouse, multiple alleles at the <I>c</I> locus include wild type, <I>c<SUP>+</SUP></I>; chinchilla, <I>c<SUP>ch</SUP></I>; himalayan, <I>c<SUP>h</SUP></I>; and albino, <I>c.</I>
8. If possible, use the same symbols for similar mutants in closely related species. As <I>a</I> is for amelanistic (tyrosinase negative) in the corn snake, it should also be reserved for albino (tyrosinase negative) in the black rat snake.
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The words "heterozygous albino" contain 19 letters. That is a lot of bandwidth, particularly if it must be written over and over when diagramming a cross.
Mendel used letter symbols for several reasons. He lacked words because "heterozygous" and other genetics terms had not been invented. And symbols were simple, clear, and easy to understand. Geneticists have continued to use symbols for much the same reasons.
Various groups of geneticists have agreed on rules for genetic symbols. These rules allow a few alphanumeric characters to indicate whether the gene is normal or mutant, dominant or recessive, allelic or independent, etc. That is quite a load of information to carry, but it can be done.
So far, there is no single set of rules for gene symbols for all species. The rules for the fruit fly are not exactly the same as the rules for the mouse. And the rules for the mouse are not exactly the same as for maize, though there is considerable agreement. As uniformity is desirable, these rules follow the <A HREF="http://www.informatics.jax.org/mgihome/nomen/table.shtml">gene nomenclature for the mouse</A>.
1. Give the mutant a unique name that is reasonably descriptive of the phenotype. Examples: amelanistic, charcoal, striped.
2. Derive the unique one to four letter symbol from the unique mutant name, and italicize the symbol if possible. Alphabet books for young children often start with "a is for apple." In the same way, <I>c</I> is for charcoal. Because <I>c</I> is already used, <I>ca</I> is for caramel.
3. Use lower case letters for all letters symbolizing a recessive mutant. Again, <I>ca</I> is for caramel, a recessive mutant gene.
4. Use an upper case letter for the first letter in the symbol for a dominant or codominant mutant. The symbol <I>T</I> is for tiger, a codominant mutant in the reticulated python.
5. The locus symbol is the same as the symbol given to the first mutant discovered at that locus. The <I>a</I> locus has the <I>a</I> (amelanistic) mutant gene and all its alleles.
6. The wild type allele is symbolized by either the <I>+</I> symbol alone or by the locus symbol with the + symbol as a superscript. The wild type allele at the <I>a</I> locus can be either <I>+</I> (if the useage is obvious) or <I>a<SUP>+</SUP></I> (to make useage absolutely clear).
7. Multiple alleles are symbolized by one or two lower case letters added to the base symbol as a superscript. In the mouse, multiple alleles at the <I>c</I> locus include wild type, <I>c<SUP>+</SUP></I>; chinchilla, <I>c<SUP>ch</SUP></I>; himalayan, <I>c<SUP>h</SUP></I>; and albino, <I>c.</I>
8. If possible, use the same symbols for similar mutants in closely related species. As <I>a</I> is for amelanistic (tyrosinase negative) in the corn snake, it should also be reserved for albino (tyrosinase negative) in the black rat snake.
