Nature's big break! Create a complete sequence of human X chromosomes!

Researchers at the National Human Genome Institute, part of the National Institutes of Health, created the first end-to-end sequence of human chromosomesThe results, published recently in the journal Nature, suggest that it is now possible to accurately produce base sequences of human chromosomes, which will allow researchers to produce complete sequences of the human genome"This achievement ushers in a new era of genomics research, " said M.D., director of the National Genomics Institute"The ability to produce truly complete sequences of chromosomes and genomes is a technological feat that will help us gain a comprehensive understanding of genomic function and inform the use of genomic information in health care." "After nearly two decades of improved human genome reference sequences is by far the most accurate and complete vertebrate genome sequenceHowever, there are still hundreds of unknown blank or missing sequencesPhoto Source: These gaps often contain duplicate fragments that are very difficult to sequenceHowever, these duplicate fragments include genes and other functional elements that may be associated with human health and diseaseBecause the human genome is so long that a sequencer consisting of about 100 million bases cannot read all the bases at onceInstead, the researchers cut the genome into smaller fragments and analyzed sequences of hundreds of bases at a time for each fragmentThese shorter sequences must be reassembledDrPh.D., a senior author at the National Human Genome Institute, likened the problem to solving a puzzle"Imagine we're going to rebuild a jigsaw puzzleIf you're using smaller pieces each containless backgrounds to find out where it comes from, especially parts of the puzzle that don't have any unique clues, such as blue skyThe same is true of human genome sequencingUntil now these fragments have been too small to put together the hardest parts of the genome puzzle"In the human chromosome including and studying the study authors and PhDs chose to complete the chromosome sequence first because it is associated with many diseases including haemophilia, chronic granulomaanddisease and Duchs muscular dystrophy Humans have two sets of chromosomes from their parents For example, a woman has biologically inherited two chromosomes from the mother and the other from the father However, the two chromosomes are not identical in their sequences and there are many differences In this study, the researchers did not sort chromosomes from normal human cells Instead, they used a special cell type with two identical chromosomes Such cells provide more sequencing than male cells with only one chromosome copy It also avoids sequence differences encountered when analyzing two chromosomes in a typical female cell The authors and their colleagues used new technology to sequence long segments Instead of preparing and analyzing small fragments, they used a method of keeping molecules basically intact These large molecules are then analyzed using two different instruments Each machine can produce a long sequence that previous instruments could not complete After analyzing human chromosomes in this way, he and his team combined many fragments of the resulting sequence using their newly developed computer program The team worked to narrow the largest remaining sequence gap on the chromosome, which is called the middle part of the chromosome, about 10,000 duplicate bases There is no "gold standard" for researchers to critically assess the accuracy of assembling such highly repetitive sequences Several validation steps were performed to help confirm the validity of the resulting sequence and its collaborators "In fact, we've never seen these sequences in our genome before and there aren't many tools to test whether our predictions are correct That's why it's important to involve experts in genomics and ensure the quality of the final product "This is part of the broader initiative of the Telomere to Telomere Alliance, which is funded in part The goal of the alliance is to produce a complete human genome reference sequence Photo Source: The Alliance continues to study the remaining human chromosomes with the goal of producing a complete sequence of the human genome over the years The researchers say they don't yet know what will be found in the newly discovered sequence, but this is an exciting unknown discovery It's an age of whole genome sequences and they're embracing it wholeheartedly Potential challenges remain For example, chromosomes and chromosomes have larger duplicate fragments than chromosomes "We know that these previously uncharted sites in our genome differ greatly from individual to individual, but it's important to begin to understand how these differences affect human biology and disease," he said "It is agreed that enhanced sequencing methods will continue to create new opportunities in the fields of human genetics and genomics () References: : "" :