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Table 2 Sample size requirements for case–control analyses of single nucleotide polymorphisms

From: Using single nucleotide polymorphisms as a means to understanding the pathophysiology of asthma

 

Dominant model

Recessive model

 

Exposure (%)

No. of cases required

Exposure (%)

No. of cases required

Allele frequency (%)

 

α = 0.05

α = 0.005

 

α = 0.05

α = 0.005

10

19

430

711

1

6113

10,070

20

36

311

516

4

1,600

2,637

30

51

308

512

9

769

1,269

40

64

354

590

16

485

802

50

75

456

762

25

363

602

60

84

661

1,107

36

311

516

  1. There were two controls per case; a detectable difference of OR is 1.5 or more; power = 80%. The allele frequencies shown are those in controls. Exposure (that is, prevalence) is that in controls assuming a diallelic locus with a dominant or recessive allele at Hardy–Weinberg equilibrium. In the dominant model, estimates are for an OR of 1.5 between cases and controls for the possession of at least one copy of disease-associated SNP by case; in the recessive model, estimates are for an OR of 1.5 between cases and controls for the possession of two copies of disease-associated SNP by case.
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Respiratory Research

ISSN: 1465-993X

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