KARYOTYPING: looks at number & appearance & of a person's Chromosomes, so can see only big structural changes (ex.: missing chrX, duplication of Chr21, etc).
Low res. ~5-10Mb. Needs culture cells.
MODERN DNA SEQUENCING: creates new complementary strands of DNA to read the original
1977 SANGER SEQUENCING: long, expensive and unable to get all variations. Accurate for small parts of genome), up to 500bp sequences per reaction, for single nucleotide variation, small insertions/deletions
1990 DNA MICROARRAYS (DNA chips): SYNTHETICALLY MAKES SECTIONS of SINGLE-STRANDED DNA & MATCHES with areas of the examined DNA on a microchip.
For short part & variations but also whole gen. - Res ~200kb
MLPA: detecs copy number changes of up to 50 loci in a single test
PCR: multitude of different types
GENE PANEL TESTING: fast tests together MULTIPLE genes (PANELS):
NEXT GENERATION SEQUENCING (NGS)
can also make WHOLE "EXOME" SEQUENCING: analysing all protein-coding sequences (2% in the genome) for clinical exams.
NGS is a general term, whereas WGS, WES are the specifics.
All these sequencing methods are done in a FRAGMENTED way, results must be put back together to see the whole.