Segregation analyses attempt to estimate from family data the characteristics (in terms of mode of inheritance, allele frequency and risk of disease in carriers) of unmeasured genetic variants that have a major impact on risk of disease.
The effect identified in our study (OR = 1.7) was stronger than in the study of Purdue but this value was observed when dominant mode of minor allele classification was applied.
The dependence of the relationship between PAF and λs on the frequency of the marker, the frequency of the causative allele, the inheritance mode of the causative allele and the extent of linkage disequilibrium is presented in the supporting information.
It also asks why there should exist genetic variants associated with susceptibility to breast cancer other than mutations in BRCA1 and BRCA2, and what might be their modes of inheritance, allele frequencies and risks.
Using the observed data from the detection data set and simplified adapting it to the bi-allelic case to derive a power estimate for the confirmatory sample using Quanto 1.2.4, we estimated that 363 trios would have a power of 97% to detect an RR effect of RR = 1.7 under a log-additive mode of inheritance (minor allele frequency 15%, αtwo-sided = 0.05).
Meta-analysis of the published summary carrier frequency data was performed (i.e., assuming a dominant mode of inheritance) because allele frequency and individual-level patient data were mostly unavailable from the authors of the studies.
A cohort of 85 GCA cases and 130 controls provides 80% power to detect an odds ratio (OR) of 2.5 or 2.9 for a dominant and recessive mode of inheritance, respectively, assuming an allele frequency of 0.35 (5% significance level); for an allele frequency of 0.5 the corresponding ORs are 3.2 and 2.5).
It should be noted that the heterozygous littermates did not demonstrate vascular mineralization, with the exception of the kidneys, and were indistinguishable from the wild-type controls, attesting to the autosomal recessive mode of the asj mutant allele.
This mode-shift in the distribution of allele frequencies in WB and PB signifies population bottlenecks.
The presence of a mosaic blocks pattern and evidences for a mode-shift in the distribution of allele frequencies found in WB and PB agrees with theoretical expectations for populations which have undergone a severe bottleneck [ 8].
