geenivarianti

Geenivarianti refers to a variant form of a gene that differs from the reference DNA sequence in an individual or population. Such variants arise through mutations and structural changes during DNA replication and recombination and can be inherited or occur in somatic cells. They range from single nucleotide changes to larger insertions, deletions, duplications, and more complex rearrangements. Most gene variants have no measurable effect on health or appearance, but some alter a gene's function or regulation and contribute to traits or disease.

Variants are typically categorized by type: single nucleotide variants (SNVs), insertions and deletions (indels), copy number variants (CNVs), and larger structural variants. Detection relies on DNA sequencing, genotyping arrays, or cytogenetic methods, and interpretation uses standardized nomenclature such as HGVS and identifiers like rsIDs in dbSNP. Population databases such as gnomAD provide allele frequencies, aiding in distinguishing common variation from rare, potentially pathogenic changes.

Functional consequences depend on context. Coding variants may change amino acids (missense), introduce stop codons (nonsense), or disrupt splicing; regulatory variants can modify expression levels. Clinically, gene variants are classified as benign, likely benign, uncertain significance, likely pathogenic, or pathogenic, guiding diagnosis, prognosis, and treatment. Pharmacogenomic variants influence drug metabolism and response, informing personalized medicine.

Examples of well-known gene variants include pathogenic BRCA1/BRCA2 alleles associated with elevated cancer risk and CFTR variants causing cystic fibrosis. Ethical considerations include reporting incidental findings, informed consent, and privacy in genomic testing. Databases and resources such as ClinVar, dbSNP, and gnomAD support research and clinical interpretation.