Polymorphic Alu insertions and the genetic structure of Iberian Basques

Area of Science:

• Population Genetics
• Human Evolution
• Molecular Anthropology

Background:

• Basque populations exhibit unique genetic characteristics.
• Previous studies suggest potential links to North African or Caucasian origins.
• Alu sequences are mobile genetic elements useful for population studies.

Purpose of the Study:

• To assess the genetic relationships of Basques within a broader European and North African context.
• To investigate the genetic heterogeneity among Basque subpopulations.
• To evaluate hypotheses regarding Basque origins using Alu insertion data.

Main Methods:

• Analysis of eight Alu insertion polymorphisms (ACE, TPA25, PV92, APO, FXIIIB, D1, A25, B65) in Basque samples.
• Compilation and comparison of Alu data from European, Caucasian, and North African populations.
• Multidimensional Scaling (MDS) plot and Analysis of Molecular Variance (AMOVA) for population structure.
• Estimation of Wright's F(ST) statistic and Wahlund's effect for Alu markers and Short Tandem Repeats (STRs).

Main Results:

• MDS and AMOVA revealed geographic population clusters but no significant genetic heterogeneity between Basque samples or with other Europeans (excluding Caucasus).
• Alu data contradicts hypotheses linking Basque origins to North African (Berbers) or Caucasian (Georgian) populations.
• On a European scale, Alu insertions showed higher F(ST) values than STR alleles, indicating greater differentiation.

Conclusions:

• Basque genetic makeup is largely European, with recent spatial heterogeneity likely driven by admixture with neighbors.
• Linguistic barriers may have modulated gene flow and contributed to observed genetic patterns.
• Alu insertion data provides insights into the relatively recent formation of Basque genetic substructure.