Table 2.

Overview of the strategies used in genetic research depending of the disease prevalence and assumptions about the genetic heredity

	Preferred first genetic research approach		Type of polymorphism usually analyzed
	Initial candidate gene	No candidate gene
Familial disorder	Linkage analysis	GWS	SNPs, microsatellite polymorphism
Hypothesis: risk genetic variant with a relative high penetrance
Sporadic and common disorder	Associations studies	GWAS GWAS-gene interaction analysis	SNPs, CNVs
Hypothesis: common risk genetic variant with a low penetrance
Sporadic	Sequencing	Massive sequencing	SNPs, CNVs, microsatellite polymorphism
Hypothesis: rare risk genetic variant with a relative high penetrance
Sporadic and rare disorder	?	?
Hypothesis: common risk genetic variant

Abbreviations: GWS, genome wide scan; GWAS, genome wide association study; SNP, single nucleotide polymorphism; CNV, copy number variation.