The application of miniplex primer sets in the analysis of degraded DNA from human skeletal remains

A new set of multiplexed PCR primers has been applied to the analysis of human skeletal remains to determine their efficacy in analyzing degraded DNA. These primer sets, known as Miniplexes, produce shorter amplicons (50-280 base pairs (bp)) than standard short tandem repeat (STR) kits, but still utilize the 13 CODIS STR loci, providing results that are searchable on national DNA databases. In this study, a set of 31 different human remains were exposed to a variety of environmental conditions, extracted, and amplified with commercial and Miniplex DNA typing kits. The amplification efficiency of the Miniplex sets was then compared with the Promega PowerPlex 16 system. Sixty-four percent of the samples generated full profiles when amplified with the Miniplexes, while only 16% of the samples generated full profiles with the Powerplex 16 kit. Complete profiles were obtained for 11 of the 12 Miniplex loci with amplicon sizes less than 200 bp. These data suggest smaller PCR amplicons may provide a useful alternative to mitochondrial DNA for anthropological and forensic analysis of degraded DNA from human skeletal remains.     

The utility of whole genome amplification for typing compromised forensic samples

Biological evidence has become invaluable in the crime laboratory; however, it may exist in limited quantity and/or quality. Given this, the ability to amplify total DNA obtained from evidence, in an unbiased manner, would be highly advantageous. Methods for whole genome amplification (WGA) have the potential to fulfill this role, resulting in a virtually unlimited supply of DNA. In the research presented, two WGA methods, improved primer extension preamplification and multiple displacement amplification (MDA), were tested using commercial kits. Control DNA, artificially degraded DNA, and DNA from fresh blood, aged blood, hair shafts, and aged bones underwent WGA, followed by short tandem repeat and mitochondrial DNA analysis. The methods did amplify DNA, but performed poorly on forensically relevant samples; the maximum amplicon size was reduced, and MDA often resulted in extraneous bands following polymerase chain reaction. Taken together, WGA appears to be of limited forensic utility unless the samples are of a very high quality.     

Simultaneous determination of total human and male DNA using a duplex real-time PCR assay

A single duplex assay to determine both the amount of total human DNA and the amount of male DNA in a forensic sample has been developed. This assay is based on TaqMan technology and uses the multicopy Alu sequence to quantitate total human DNA and the multicopy DYZ5 sequence to quantitate Y chromosomal (male) DNA. The assay accepts a wide concentration range of input DNA (2 muL of 64 ng/microL to 0.5 pg/microL), and also allows detection of PCR failure. The PCR product sizes Alu (127 bp) and DYZ5 (137bp) approximate that of the smaller short tandem repeats (STRs) which should make the assay predictive of STR success with degraded DNA. The assay was optimized for probe/primer concentrations and BSA addition and validated on its reproducibility, on its human specificity, on its nonethnic variability, for artificial mixtures and adjudicated casework, for the effect of inhibitors and for state of DNA degradation. This assay should prove very usual in forensic analyses because knowing the relative amounts of male versus female DNA can allow the examiner to decide which samples may yield the most probative value in a case or direct the samples to methods that would yield the greatest information.     

中国汉族人mtDNA控制区异质性遗传规律

目的探讨中国汉族人mtDNA控制区异质性分布情况和遗传规律。方法将人mtDNA控制区扩增成6个部分互相重叠的片段,利用已建立的DHPLC技术分析其异质性规律。结果对150例汉族无关个体的多种组织检测,发现异质性个体的发生率达34%(51/150);个体的组织mtDNA异质性检出率最高为脑(50/150)、心肌(48/150)、最低为骨骼(22/150);本组共发现mtDNA控制区异质性位点有36个;同一个体可有多个异质性位点,最多的不超过3个;未发现异质性发生率有性别差异;超过41岁的高年龄组的异质性发生率(27/59)高于低年龄组(24/91);同一个体在2年前后取的血样,异质性检测结果一致;同一母系不同成员的异质性位点相同,但异质性mtDNA的含量有差异。结论DHPLC检测mtDNA控制区异质性具有高分辩力;mtDNA控制区异质性在中国汉族人中广泛存在;上述结果可作为mtDNA控制区多态性作个人认定和亲权鉴定的指导性资料。