Practice question

Microsatellites consist of tandemly repeated units of one to six base pairs dispersed throughout genomes. Variation among individuals originates from difference in copy number of repeat motifs at orthologous loci, caused by replication slippage leading to expansion or contraction of repeats. Base composition of repeat motif remains constant, for example CA dinucleotide, and genomic location is conserved. Length variation is secondary consequence of repeat number change. Therefore, allelic diversity at microsatellite loci directly reflects hypervariability in number of repeat iterations.