Repetitive Elements in Humans

Abstract

Repetitive DNA in humans is still widely considered to be meaningless, and variations within this part of the genome are generally considered to be harmless to the carrier. In contrast, for euchromatic variation, one becomes more careful in classifying inter-individual differences as meaningless and rather tends to see them as possible influencers of the so-called ‘genetic background’, being able to at least potentially influence disease susceptibilities. Here, the known ‘bad boys’ among repetitive DNAs are reviewed. Variable numbers of tandem repeats (VNTRs = micro- and minisatellites), small-scale repetitive elements (SSREs) and even chromosomal heteromorphisms (CHs) may therefore have direct or indirect influences on human diseases and susceptibilities. Summarizing this specific aspect here for the first time should contribute to stimulating more research on human repetitive DNA. It should also become clear that these kinds of studies must be done at all available levels of resolution, i.e., from the base pair to chromosomal level and, importantly, the epigenetic level, as well.

Eukaryogenesis: The Rise of an Emergent Superorganism

“…In eukaryotes, much of the genome is composed of viral elements. For example, the human genome is composed of > 20% LINES and ~ 13% SINES, both of which are repetitive elements derived from retroviruses ( Liehr, 2021 ). In animals, the ARC genes underlying synaptic plasticity required for memory are clearly derived from retroviruses ( Budnik and Thomson, 2020 ) and the mammalian placenta relies on endogenous retroviral elements to function ( Blond et al, 2000 ).…”

The Role of Human Satellite III (1q12) Copy Number Variation in the Adaptive Response during Aging, Stress, and Pathology: A Pendulum Model

“…The estimated total fraction of repetitive sequences in human genome varies from approximately one-half [1] to over two-thirds [2]. While first studies on the human genome size in the 1990s elicited an estimate that the human genome harbored 50,000-100,000 protein-coding genes [3], by 2008, RNA-seq further identified an ocean of non-coding transcribed sequences, divided into long noncoding RNAs (lncRNAs), antisense RNA and miscellaneous RNA, and finally, in 2018, 20,000 protein-coding genes,~15,000 pseudogenes and, impressively,~17,000-25,500 non-coding RNAs were catalogued [4]. Indeed, the coding RNA (mRNAs) covers merely 1-2% of the genome sequences, whereas a much larger part of the genomes is known to be actively transcribed to produce non-coding RNAs (ncRNAs) [5][6][7].…”

Mutated KLF4(K409Q) in meningioma binds STRs and activates FGF3 gene expression

“…FGF3 -IN2.1 and IN2.2 can be designated as microsatellites, varying (1–6 bp) length stretches of repetitive DNA motifs ( Liehr, 2021 ). They consist of GGAT and GGGT tetra-nucleotides, which in tandem order form a KLF4 K409Q consensus motif ( Figure 4 F) in trans orientation with FGF3 gene transcription.…”