Relationship between Transposable Elements and behavioral traits: insights from six genetic isolates from North-Eastern Italy

Half of the human genome is derived from Transposable Elements (TEs), among which Alu, LINE-1 and SVA are particularly represented. Germline transposition of TEs generates polymorphisms between individuals and may be used to study association with phenotypes and inter-individual differences. Italy presents an increased number of isolated villages compared to other European groups, and these isolates provide a desirable study subject to understand the genetic variability of the Italian peninsula. Therefore, we focused on the association between polymorphic TEs, behavioral traits (tobacco use and alcohol consumption), and Body Mass Index (BMI) variations, which could lead to an increased risk of developing addiction-related or metabolic diseases. We identified 12,709 polymorphic TEs in 589 individuals from six isolates: classical population genetics analyses showed that while closely related to other European populations, the isolates tend to cluster amongst themselves and are dominated by drift-induced ancestral components. Several TEs were also significantly associated with behavioral traits (tobacco use or alcohol consumption) or with BMI variations and some of them have a functional role. These results suggest that polymorphic TEs may significantly impact inter-individual and inter-population phenotypic differentiation, while also functioning as variability markers and potentially having a role in susceptibility to medical conditions.