Comparative informativeness for linkage of multiple SNPs and single microsatellites

Area of Science:

• Genetics
• Bioinformatics
• Statistical Genetics

Background:

• Single nucleotide polymorphisms (SNPs) are widely used biallelic markers in genetic linkage studies due to their genomic abundance, stability, and ease of scoring.
• The information ratio (IR) quantifies the informativeness of genetic markers in linkage analysis.

Purpose of the Study:

• To determine the information ratio (IR) of closely spaced single nucleotide polymorphisms (SNPs) in simulated nuclear families and affected sib pairs (ASPs).
• To compare the IR of SNPs with that of a multi-allelic microsatellite marker.

Main Methods:

• Simulated 1000 nuclear families (2-5 children) and 1000 ASPs.
• Generated SNP marker data for strings of 1-10 loci with varying minor allele frequencies (MAF) and microsatellite data with 3-9 equally frequent alleles.
• Analyzed SNP data using multipoint analysis and as composite markers (haplotypes), calculating the IR for each scenario.

Main Results:

• Multipoint analysis of 5-7 closely spaced SNPs achieved an IR of approximately 100% in nuclear families.
• For ASPs, 7-10 SNPs yielded an IR of only 70-80%.
• A microsatellite with 9 alleles showed an IR (86-88%) comparable to 4-5 SNPs in nuclear families; composite marker analysis of SNPs performed less effectively.

Conclusions:

• Closely spaced SNPs, particularly when analyzed with multipoint methods, are highly informative for genetic linkage in nuclear families.
• Affected sib pair studies may require a larger number of SNPs to achieve high informativeness compared to nuclear families.
• The choice of marker type and analysis method impacts the efficiency of genetic linkage studies.