Human genomes vary quite a bit from individual to individual. These differences include single nucleotide changes, or "spelling mistakes" in the DNA sequence, but even more variation comes from structural variants, which include additions, deletions and rearrangements of large segments of DNA. A recent study used multiple advanced technologies to dive deeper than ever before to comprehensively characterize the structural variants present in three families, and what their functional consequences might be.
Genome sequencing has become much faster, more accurate and less expensive over the past decade. As a result, more and more human genomes are being sequenced, and our knowledge of what those sequences actually mean for function and disease is growing rapidly.
It has also become clear that the more we learn, the more we appreciate just how little we still know about human genomics. While a linear sequence of ATGCs looks tidy, our genomes are actually dynamic entities that harbor considerable differences between individuals - differences that can alter traits contributing to both normal function and disease.
The genetic difference between individuals contributes to our individuality. These differences include millions of single nucleotide variants - where, for example, one person may have an A, another may have a C at a given position. There are also hundreds of thousands of structural variants (SVs). SVs include segments of DNA that are inserted into or deleted from the genome, segments that are duplicated, and segments that are inverted. SVs are more difficult to identify than single nucleotide variants, and hence it has been unclear just how many SVs really exist in a given human genome.
Now a paper entitled "Multi-platform discovery of haplotype-resolved structural variation in human genomes," published in Nature Communications, delves deeper into individual genomic differences than ever before.