| The following is an example to illustrate the CYP naming system using CYP3A4: |
| The standard abbreviation for human cytochrome P450 is CYP. |
| Families of the isozyme which share greater than 40% protein sequence homology with each other are designated by the first number following the cytochrome P450 designation, e.g., 3. |
| Subfamilies which share greater than 60% homology with each other are differentiated by the letter following the family designation, e.g., A. |
| Single members of subfamilies represent a particular gene and are designated by the number following the subfamily description, e.g., 4. |
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