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Population Genetics and Statistics for Forensic Analysts

Non-autosomal DNA Analysis

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The use of mitochondrial DNA (mtDNA) and Y-chromosome markers has become more prevalent in forensic science. Both methods characterize non-autosomal DNA, which does not follow the basic rules of Mendelian genetics. The statistical assessment can still be applied when comparing the DNA profiles obtained from forensic evidence to that from a known individual. A common approach is simply to state the number of occurrences of a mtDNA sequence or Y-STR type present in the database. This approach is commonly referred to as the counting method. This is the approach adopted by the FBI for mtDNA analysis.22 Likelihood ratios provide another approach to statistical assessment of non-autosomal DNA results.05

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