Characterizing nucleotide variation and expansion dynamics in human-specific variable number tandem repeats.

Area of Science:

• Genomics
• Human Evolution
• Bioinformatics

Background:

• Variable number tandem repeats (VNTRs) are polymorphic and mutable elements in the human genome, crucial for evolution and variation.
• Despite their significance, VNTRs remain understudied due to their size, variability, and noncoding locations.

Purpose of the Study:

• To collectively analyze human-specific VNTR expansions, focusing on their nucleotide composition, allelic variation, and evolutionary dynamics.
• To investigate VNTR structural organization and identify population-specific differences in composition and length.

Main Methods:

• Utilized long-read human genomes from the Human Genome Structural Variant Consortium to determine VNTR nucleotide composition.
• Confirmed repeat unit composition in over 3000 short-read samples from the 1000 Genomes Project.
• Compared VNTR composition and length across human superpopulations and archaic human genomes.

Main Results:

• Identified highly structured repeat motif organization in VNTRs, shaped by deletion and duplication events.
• Found largely similar VNTR compositions across 1000 Genomes Project superpopulations, with exceptions in PCBP3.
• Observed significant length differences in VNTRs within ART1, PROP1, DYNC2I1, and LOC102723906 across superpopulations.
• Noted that most analyzed VNTRs are expanded in archaic human genomes but show stability within recent generations.

Conclusions:

• Repeat motif variability, composition, and length are key factors for characterizing VNTRs and their role in genomic variation.
• VNTRs exhibit complex evolutionary patterns, with population-specific and archaic human expansions.
• Further research into VNTRs can illuminate their contribution to human genomic diversity and evolution.