Table 1.

Genetic screening tests while diagnosing rare disease.

Diagnostic type	Methodology	Resolution	No. of loci screened	Variants detected	Diagnostic yield
Traditional genetic screening	G-band karyotyping	10Mb	500	Larger than 5Mb	Low
	FISH	>300kb	More than 300	Gene rearrangements, aneuploidy and malignancies	Low
	CMA	100kb	2 million	CNVs	Medium
Next generation sequencing	Targeted sequencing	20kb	40 million	SNVs in coding region	High
	WES	1bp	50 million	Variants in exonic regions	High
	WGS	1bp	3 billion	Variants throughout the genome	Highest

Note: Genetic screening tests ranges from analyzing chromosome via light microscope to detecting copy number variation to detecting specific coding regions to the full genome. With increase in resolution, the number of variants detected also increases. WGS detects the highest number of variants by covering the entire genome showcasing the largest diagnostic yield making it an ideal technique for detecting variants left undiscovered from traditional techniques.