Researchers generate complete human X chromosome sequence

There is a space missing in the title ("X chromosome").

From the article: "Repetitive DNA sequences are common throughout the genome and have always posed a challenge for sequencing because most technologies produce relatively short "reads" of the sequence, which then have to be pieced together like a jigsaw puzzle to assemble the genome. Repetitive sequences yield lots of short reads that look almost identical, like a large expanse of blue sky in a puzzle, with no clues to how the pieces fit together or how many repeats there are. . . . Filling in the remaining gaps in the human genome sequence opens up new regions of the genome where researchers can search for associations between sequence variations and disease and for other clues to important questions about human biology and evolution."

Or, to make this more simple: Finding the complete DNA sequence of chromosomes is difficult. That's because some parts of the sequence are highly repetitive. Using a new type of lab machine, the scientists were able sequence the repetitive parts of the X chromosome. This gives a more complete picture of the X chromosome. And that can help scientists fight diseases and understand human biology better.

So how do you actually isolate one chromosome to sequence it?

The press release is better than the link:

https://www.genome.gov/news/news-release/NHGRI-researchers-g...

Having a complete and accurate map is important for researchers who study the X-chromosome.

Long sequences reads allowed them to map the highly repetitive chromosome. Most sequencing is done by high-throughput short reads.

The technology can theoretically be used to map other regions of the genome which are highly repetitive.