Analysis of 49 autosomal SNPs in three ethnic groups from Iran: Persians, Lurs and Kurds

Genotyping of 49-plex autosomal SNP panel in Iranian Turkmens ethnic group

A total of 94 unrelated individuals from Turkmens ethnic group in Iran were typed for forty-nine of the autosomal single nucleotide polymorphisms (SNPs) in the SNPforID 52plex using the SNaPshot assay. Allele frequencies are presents for the 49 SNPs. No deviation from Hardy-Weinberg equilibrium (HWE) was observed in all but one of the 49 SNP systems and no significant linkage disequilibrium was detected for any SNP pairs. F_IS and F_ST were estimated. A statistically significant global F_ST value was obtained when Turkmens ethnic group were compared with other 20 populations in Turkey, Israel, Pakistan, India, China, Taiwan, Japan, Thailand, Siberia, Algeria, Somali, Uganda, Mozambique, Angola, Nigeria, Russia, Slovenia, Sweden, France and Spain. All but 11 pairwise F_ST values were statistically significant. Multidimensional scaling plot drawn based on the pairwise F_ST values showed that the Turkmens ethnic grouped with populations geographically close to Iran and other Middle-Eastern populations. The cumulative values for the match probability using the 49 SNPs was 5.65 × 10^-19 consistent to a combined power of discrimination of >99.99999% and the mean exclusion probability was 99.95%.

Expansion of a SNaPshot assay to a 55-SNP multiplex: Assay enhancements, validation, and power in forensic science

A previously developed multiplex assay with 44 individual identification SNPs was expanded to a 55plex assay. Fifty-four highly informative SNPs and an amelogenin sex marker were amplified in one PCR reaction and then detected with two SNaPshot reactions using CE. PCR primers for four loci, 28 single-base extension primers, and the reaction conditions were altered to improve the robustness of the method. A detailed approach for allele calling was developed to guide analysis of the electropherogram. One hundred and eighty unrelated individuals and 100 father-child-mother trios of the Han population in Hebei, China were analyzed. No mutation was found in the SNP loci. The combined mean match probability and cumulative probability of exclusion were 1.327 × 10(-22) and 0.999932, respectively. Analysis of the 54 SNPs and 26 STRs (included in the AmpFLSTR Identifiler and Investigator HDplex kits) showed no significant linkage disequilibriums. Our research shows that the expanded SNP multiplex assay is an easily performed and valuable method to supplement STR analysis.

Current status of the use of single-nucleotide polymorphisms in forensic practices

Forensic geneticists often use short tandem repeats (STRs) to solve cases. However, STRs can be insufficient when DNA samples are degraded due to environmental exposure and mass disasters, alleged and real relatives are genetically related in paternity or kinship analyses, or a suspect is lacking. In such cases, single-nucleotide polymorphisms (SNPs) can provide valuable information and thus should be seriously considered as a tool to help resolve challenging cases. In this review, the current status of SNP analyses in forensic applications and the comparative advantages and disadvantages of SNPs with other biomarkers are discussed.