Gendosering

Gendosering, or gene dosage, describes the number of copies of a gene present in a cell's genome and the corresponding level of gene expression. Variation in dosage arises from copy-number variations, duplications, deletions, or whole-chromosome aneuploidy, and can alter the amount of gene product produced. The biological effect of dosage changes depends on the gene's dosage sensitivity, regulatory context, and compensatory mechanisms. Some genes tolerate copy-number changes with little phenotypic impact, while others cause developmental abnormalities or disease when dosage is increased or decreased.

Common examples include Down syndrome, caused by an extra copy of many chromosome 21 genes; various neurodevelopmental disorders linked to copy-number variations; and cancer, where amplifications or deletions alter dosage of oncogenes and tumor suppressors, influencing proliferation and survival.

Gene dosage is measured by genomic techniques such as comparative genomic hybridization, SNP arrays, and sequencing-based depth-of-coverage analyses, often complemented by expression data to separate dosage from regulation. Understanding dosage effects informs fields from developmental biology to gene therapy, as altering copy number or expression levels may target disease pathways. The concept also relates to dosage compensation, where organisms balance gene expression between sexes despite differing chromosome complements.