Microvariants

Microvariant is a term used in genetics and related disciplines to describe a variant that involves only small-scale changes, typically affecting a single nucleotide or a short stretch of DNA, or a partial repeat unit within an STR locus. This contrasts with macrovariants, which involve larger structural changes such as large deletions, duplications, or chromosomal rearrangements.

Microvariants arise through typical mutational processes such as replication errors and mutagen exposure, and they contribute to genetic diversity among individuals and populations. They can occur in coding sequences, potentially altering amino acids, or in noncoding regions, affecting regulation or splicing, with possible benign or pathogenic consequences depending on context.

In forensic genetics, microvariants are specifically used to describe alleles at short tandem repeat loci that show partial repeat units, often denoted with decimal notation like 14.2; these require careful interpretation in haplotype analysis.

Detection relies on DNA sequencing, targeted genotyping, or STR profiling; interpretation uses reference databases, population allele frequencies, and clinical context. Not all microvariants have known functional effects, and many are considered variants of uncertain significance.

Overall, microvariants illustrate the fine-scale spectrum of genetic variation that complements larger structural variants in shaping genome function and diversity.