The Human Genome Project was an inward voyage of discovery, and since this feat, genome sequencing has got more accessible and more affordable.
Long story short, this sequencing project involved the mapping of the entire human genome- identifying and mapping all of the genes present in the humans so as to determine the sequence of nucleotide base pairs that make up the human DNA. This involved snipping the
DNA into pieces which was picked by a sequencer, and then with the help of a computer, arranging the fragments in order to elucidate the entire genome sequence of an individual.
The current sequencing technologies called the second generation sequencing costs about a fraction of the earlier costs and the sequence data generated generally consists of billions of short DNA reads or words that are about 100-150 words in length. But on the downside, since the sequences are snapped in between to make short sequences, some parts of the genome can be missed—about 5% of it. Owing to which any vital deletions or insertions are rendered undetectable.
However, the scientists are now exploring an alternative- the long sequencing method to illuminate the dark corners of the genome which were conveniently missed in the case of short
sequencing.For the first time now, a team of researchers from Stanford has used the long sequencing method to diagnose a patient- Ricky Ramon, whose symptoms when observed pointed to a rare genetic condition called the Carney Complex.
The Carney Complex is a genetic disorder that increases the risk of the individual developing tumors in the heart and other parts of the body. Mr.Ramon who has already undergone multiple surgeries in the past to get each of these tumors removed, is now being considered for a heart transplant. But this move required a firm backing through medical evidence.
The scientists therefore considered the long read sequencing method and have now discovered a deletion of more than 2,000 base pairs in Ramon’s genome, confirming a diagnosis of Carney complex.
Although superiorly effective than the short read method, this method costs about 5-6x more in comparison.
“If we can get the cost of long-read sequencing down to where it’s accessible for everyone, I think it will be very useful,” said Mr.Euan Ashley, the study’s senior author and a professor of cardiovascular medicine, genetics and biomedical data science at Stanford, in a statement.
