Skip to main content

Table 6 Comparison of two-point vs. multipoint linkage scores under various non-null simulation conditions.

From: Design considerations in a sib-pair study of linkage for susceptibility loci in cancer

Simulation Model Marker Interval Z c Z p Z mc Z mp
No Heterogeneity a 5 cM 3.26 3.24 3.62 3.60
  10 cM 2.94 2.91 2.85 3.36
  20 cM 2.36 2.30 2.14 2.52
Locus Heterogeneityb 5 cM 3.10 3.08 3.75 3.53
  10 cM 2.76 2.70 2.72 3.13
  20 cM 2.05 2.01 1.91 2.23
Marker Heterogeneity – Mildc 5 cM 2.80 2.72 3.57 3.24
  10 cM 2.62 2.54 2.59 2.99
  20 cM 2.22 2.13 2.14 2.35
Marker Heterogeneity- Severed 5 cM 2.10 1.95 2.61 2.35
  10 cM 1.70 1.56 1.49 1.86
  20 cM 1.42 1.27 1.18 1.33
  1. All simulations employed 20 replicates of 500 families with 2 affected and 2 unaffected sibs, all sibs typed, no parents or children typed.
  2. a Baseline risk of 0.018, a relative risk to carriers of 20, allele frequency of 0.003, with a lifetime penetrance of 0.27, no genetic heterogeneity.
  3. b Baseline risk of 0.018, a relative risk to carriers of 20, allele frequency of 0.003, with a lifetime penetrance of 0.27, and a less common (allele frequency 0.001), equally penetrant unlinked predisposition syndrome.
  4. c Two populations modeled in an 80%/20% mixture: 1) marker allele frequencies for all markers [0.25,0.25,0.25,0.25], disease allele 0.00325; 2) marker alleles [0.4,0.3,0.2,0.1], disease allele 0.002.
  5. d Two populations modeled in an 80%/20% mixture: 1) marker allele frequencies for all markers [0.25,0.25,0.25,0.25], disease allele 0.0035; 2) marker alleles [0.4,0.3,0.2,0.1], disease allele 0.001.