copynumberdependent

Copy-number dependent, sometimes written as copy-number-dependent, is a term used in genetics to describe situations in which the level of gene expression, phenotype, or cellular function varies in relation to the number of copies of a particular gene or genomic segment present in the genome. Copy number can be altered by duplications, deletions, or more complex structural variations, and such changes are collectively known as copy-number variations (CNVs).

It is commonly associated with dosage-sensitive genes, where under- or overexpression due to copy-number change leads to disease or altered traits. Haploinsufficiency occurs when a single functional copy is insufficient for normal function; triplo­sensitivity refers to harmful effects from an extra copy. In cancer, amplifications and deletions of chromosomal regions can drive tumor behavior by changing the expression of oncogenes or tumor suppressors, in a copy-number dependent manner.

Detection relies on techniques that measure DNA copy number, such as array comparative genomic hybridization, SNP arrays, and sequencing-based depth-of-coverage analyses; validation may use quantitative PCR or fluorescence in situ hybridization. Understanding copy-number dependency helps interpret variable penetrance of CNVs, guide genetic diagnosis, and inform therapeutic strategies.

See also: copy-number variation, dosage compensation, haploinsufficiency, triplo­sensitivity.