When people think of DNA, they usually think of genes, the parts that code for proteins and drive inherited traits. But there ...

The type of repetitive DNA contributing most to cancer detection was the largest subfamily of Alu elements, called AluS; the blood plasma of people with cancer had less of it than usual.

While all human chromosomes contain repeats, more than 30 million letters of the Y chromosome — out of 62.5 million — are repetitive sequences, sometimes called satellite DNA or junk DNA.

Though small, the Y chromosome has intimidated many researchers because it has so many repetitive bits of DNA, says Adam Phillippy, a bioinformatics researcher at the U.S. National Human Genome ...

This technique doesn’t work with repetitive DNA where lots of the pieces are identical. Because of this, the “completed” human reference genome announced in 2003 was actually far from complete.

The rest are nonfunctional repetitive sequences long deemed “junk DNA,” though scientists now know that it’s not actually junk. A lot of that genetic gibberish can affect how genes function.