Devising a multiplex DNA typing system to identify the third-degree kinship

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Arriving at a conclusion that two individuals are third degree relatives (e.g. cousin) via DNA analysis is a difficult task as the purported individuals have only a 25% chance of sharing common alleles at any given locus. In order to increase the certainty of the relationship, experts often resort to hypervariable minisatellite loci because a pair of individuals can demonstrate high likelihood ratios (LRs) in the event that they share rare alleles. We firstly investigated the comparison of allele structures in Thai, Han Chinese, and Japanese populations. The great majority of alignable Asian alleles showed their closest structural relative in Asia. This rapidly evolving minisatellite can therefore serve as a lineage marker for exploring recent events in human population history and dissecting population structure at the fine-scale level, as well as being an extremely informative DNA marker for personal identification. we then examined third degree relatives from two groups of siblings … More using two hypervariable minisatellite loci. Relationships were not established because no alleles were shared between the two groups ; albeit sharing of alleles within each group was noted in moderation. We also estimated the distribution of LRs in a variety of kinships (parent-child, siblings, two s! iblings etc.) using a commercially available typing kit which simultaneously amplifies 15 STR loci. Although the STR system is extremely useful in establishing individual identification when both parents, or two or more children (or siblings) are available for comparison it is highly unlikely that the system will be effective in third degree kinship analyses. This postulation is based on our study of samples obtained from known third degree relatives in which we attempted a microsatellite-based approach to establishing kinship. However, unfortunately with microsatellites alone the calculated LR was less than 1, which is insufficient for positive identification. Consequently, a more effective method such that estimates the proportion of chromosomal sharing would be more advantageous in comparison to attempting to demonstrate allelic hypervariability at several loci. To date we have analyzed 382 dinucleotide loci distributed throughout the human genome in order to estimate the length proportion of shared haplotypes between two individuals in varying modes of kinship. The initial data we have obtained is promising and is currently being carefully analyzed. Less