Biomedical Engineering Reference
In-Depth Information
Chapter 2
A Survey of Next-Generation-Sequencing
Innovative application of new technologies in research is one of the major factors
driving advances in knowledge acquisition. In 1977, Maxam and Gilbert reported
an approach in which terminally labeled DNA fragments were subjected to base-
specifi c chemical cleavage and the reaction products were separated by gel electro-
phoresis (Maxam and Gilbert 1977 ). In an alternative approach, Sanger described
the use of chain-terminating dideoxynucleotide analogs that caused base-specifi c
termination of primed DNA synthesis (Sanger et al. 1977 ; Chap. 1 ). Improvements
of the Sanger method led to utilization in the research community and eventually in
the clinical diagnosis of many genetic disorders (
sites/GeneTests/ ). In a factory-based format, Sanger sequencing was the method of
choice for the fi rst human genome at an estimated cost of $2.7 billion (Fig. 1.1 ;
Chap. 1 ) . In 2008, by comparison, the genome of Dr. James Watson was sequenced
over a 2-month period for less than $1 million (Wheeler et al. 2008 ). With the com-
mercial availability of high-throughput massively parallel DNA sequencing plat-
forms in the past few years, complete sequencing of the whole human genome can
be done commercially today in 2-3 months at a cost below $10,000 (Bick and
Dimmock 2011 ; Fig. 1.1 ) . Since their introduction, next-generation-sequencing
(NGS) technologies have constantly improved and the costs have steadily decreased.
A legitimate question therefore is what role targeted gene capture will play if
whole-genome sequencing (WGS) can be done for about $1,000 in the future, with
the ability to survey the human genome in an unbiased manner. This chapter
describes NGS technologies and briefl y explores how they have been translated
into molecular diagnostics. The clinical applications of NGS will be covered in
detail in Chaps. 4-8.
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