obsolete functional copy number complement true Decided to implement copy number related classes at the sequence level, rather than the sequence feature level. Replaced by GENO:0000963. The notion of 'functional copy number' (aka 'genetic dosage') describes how many 'functional' copies of a sequence are present in a genome - i.e. sequences that retain their normal activity and/or produce gene products that retain their normal activity. In diploid organisms, the normal dosage is 2 for autosomal genes/regions. Dosage increases if there is a duplication of the gene/region. Dosage decreases if there is either a deletion of a gene/region, or an inactivating mutation that eliminates gene function. This latter condition sets it apart from the notion of a 'copy number complement', which reflects how many actual copies of a sequence exist in a genome. Addition of a non-functional allele of a gene will increase its genomic sequence complement count (i.e. its copy number), but not increase its dosage. Formerly considered modeling this as an informational entity, defined as "An information entity that describes the total number of functional copies of a gene or region of sequence in a particular genome." As for copy number complements, the defining 'sequence' here is specified in terms of a location on a reference sequence - typically the location where a gene or set of genes resides. But the criteria for membership in a functional copy number complement require only that the feature can perform the functions associated with the gene or genes at the defining location. A gene allele that varies by only one nucleotide from the wild-type gene may not qualify if that alteration eliminates the function of the allele. This represents an important distinction between 'copy number' and 'functional copy number'. The former is not concerned with the functionality of sequence copies - only that there is a duplication of sequence in the genome. Thus, the addition of a non-functional allele of a gene will increase its copy number, but not increase its 'functional copy number (aka its dosage). functional feature complement A set of all features representing *functional* versions of a specified sequence (typically that of a gene) in a particular genome. genetic dosage