VNTR Analysis
Variable Number Tandem Repeat Polymorphisms
Unlike SNPs, which involve individual nucleotides, VNTRs involve short nucleotide sequences found at a specific location in the genome. These sequences are typically 10-100 base pairs in length and occur in clusters where the sequence is repeated several times. The number of repeats varies among individuals. Genotypes are determined by reading the repeats found in each of two alleles and each variant behaves as an inheritable allele.
Consider the following DNA sequences for two individuals at a particular location in their genome.
Illustration
- Allele 1
- …TAACGG | AGTTCGCGTGA | AGTTCGCGTGA | GACTAT…
- Allele 2
- …TAACGG | AGTTCGCGTGA | AGTTCGCGTGA | AGTTCGCGTGA | AGTTCGCGTGA | GACTAT…
Both individuals have the repeating 10-base sequence (shown in red), but the first individual has two repeats of the sequence, while the second has four repeats.
