TWGDAM validation of a nine-locus and a four-locus fluorescent STR multiplex system.

The Gene Print PowerPlex 1.1/Amelogenin and FFFL Fluorescent STR Systems have been validated following the recommendations presented by the Technical Working Group on DNA Analysis Methods (TWGDAM). The PowerPlex 1.1/Amelogenin System supports simultaneous amplification of eight short tandem repeat loci and the Amelogenin gender identification marker. The loci D16S539, D7S820, D13S317, and D5S818 are labeled with fluorescein (FL) while the loci CSF1PO, TP0X, TH01, vWA and Amelogenin are labeled with carboxy-tetramethylrhodamine (TMR). The FFFL Multiplex System is composed of the loci F13A01, FESFPS, F13B, and LPL, each labeled with fluorescein. We have observed no overlap of alleles across loci labeled with an individual fluorescent dye. Samples of each system were amplified and labeled in a single reaction, separated by electrophoresis through a denaturing polyacrylamide gel, and amplified alleles detected using a Hitachi FMBIO Fluorescent Scanner. Alterations from the standard amplification protocols in cycle number and annealing temperature generally produced excellent results. In experiments testing sensitivity as little as 0.2 ng of DNA template could be detected. As expected, different body fluids from the same individuals generated identical DNA profile results. Template DNA derived from blood-strains deposited on a variety of matrix supports displayed robust amplification except for material derived from deposits on wood and Japanese orchid leaves. Mixtures of DNA templates could be interpreted with the minor component present in as little as ten percent of the total sample. Monoplex and multiplex amplifications produced identical amplified allele patterns, indicating that STR multiplex systems save template and increase efficiency in the amplification procedure without loss of quality. Analyses of genotype frequencies in African-American, Caucasian-American and Hispanic-American populations using all twelve loci were used to determine matching probabilities smaller than 1 in 1.14 x 10(8) and 1 in 2658 for the PowerPlex 1.1 and the FFFL Multiplex Systems, respectively. The matching probability achieved with the two systems combined is smaller than 1 in 3.03 x 10(11). The independence of alleles within loci was generally demonstrated by applying the exact test to demonstrate Hardy-Weinberg Equilibrium. All of the studies performed indicate that the PowerPlex 1.1/Amelogenin and FFFL Multiplex Systems are powerful, robust, and reliable investigative tools that can be used in the analysis of forensic samples.

Development and population study of an eight-locus short tandem repeat (STR) multiplex system.

Amplification of short tandem repeat (STR) loci has become a useful tool for human identification applications. To improve throughput and efficiency for such uses, the polymorphic STR loci CSF1PO, TPOX, TH01, vWA, D16S539, D7S820, D13S317, D5S818, F13A01, FESFPS, F13B, and LPL have been evaluated, developed, and configured into fluorescently labeled multiplex systems. Eight of these STR loci were combined to generate the PowerPlex System, a two-color multiplex system that supports rapid, accurate, reliable analysis and designation of alleles. The remaining four loci comprise the FFFL System, a one-color multiplex system. The PowerPlex System may be evaluated alternatively as two one-color, four-locus multiplex systems, CTTv Multiplex and GammaSTR Multiplex. The products of multiplex amplification may be analyzed with a variety of fluorescence detection instruments. Determination of genotypes of over 200 individuals from each of three different population/ethnic groups revealed independence of inheritance of the loci and allowed calculation of matching probability, typical paternity index, and power of exclusion for each multiplex.

Reuse of denaturing polyacrylamide gels for short tandem repeat analysis.

Denaturing polyacrylamide gel electrophoretic analysis of amplified polymorphic short tandem repeat (STR) loci using fluorescent markers is a mainstay of forensic and paternity testing. To reduce the drawback of preparing gels or using expensive precast gels, we have developed a simple and rapid method to reuse gels between 2 and 8 times over a period of several days. Following the initial electrophoresis and scan, the original samples are removed from the gel by a 1-1.5-h reverse-electrophoresis step. This step heats the gel for the next set of samples and can be performed several days after the initial electrophoresis. Sample bands remain sharp on subsequent runs, but edge effects (frowning of the outside lanes) become progressively worse and ultimately limit gel reuse. Well distortions and separation of the gel from the plates become problems if the gel is used more than twice. However, degassing the gel solution and bonding the gel to both plates eliminate these problems. Precast gels also can be used multiple times. Using this technique, we have successfully analyzed samples amplified with a nine-locus multiplex system and characterized the separated products using a fluorescent scanner and software.

Analysis of allele distribution for six short tandem repeat loci in the French Canadian population of Québec.

Short tandem repeat (STR) loci represent a rich source of highly polymorphic markers in the human genome which are useful for the purposes of forensic identification and determination of biological relatedness of individuals. Here, as a part of an ongoing extensive study, we report the analysis of a multilocus genotype survey of 642 to 870 chromosomes in the French Canadian Caucasian population of Québec at six STR loci. The loci HUMCSF1PO, HUMTPOX, HUMTH01, HUMF13A01, HUMFESFPS, and HUMvWA were typed using two multiplex polymerase chain reactions (PCR). Amplified DNA samples were subsequently analyzed by polyacrylamide gel electrophoresis followed by silver staining. The heterozygote frequencies of the loci range from 0.614 to 0.820 (0.661 to 0.818 expected) and the number of alleles from 7 to 12 per locus. Although statistically significant deviation from Hardy-Weinberg expectations of genotype frequencies was noted at some loci by one or more tests, in general, the genotype frequencies are well estimated from the product of allele frequencies at all loci. The most frequent six-locus genotype is expected to occur in the French Canadian population with a frequency of 3.50 by 10(-5) and together, these six loci have an average probability of discrimination of 0.9999985. The study presented here indicates that these six STR loci are informative genetic markers for identity testing purposes in the French Canadian Caucasian population of Québec.

Multiplex systems for the amplification of short tandem repeat loci: evaluation of laser fluorescence detection.

Short tandem repeat (STR) loci are ideal markers for personal identification and for genomic mapping. Two fluorescent multiplex systems, each designed for simultaneous PCR amplification of four polymorphic STR loci (HUMCSF1PO, HUMTPOX, HUMTH01 and HUMVWFA31, and HUMF13A01, HUMFESFPS, HUMBFXIII and HUMLIPOL), were evaluated on three laser fluorescence detection instruments. Concordant DNA typing results were obtained with all three detection methods. These fluorescent multiplex STR systems offer an accurate, reproducible and versatile method of DNA profiling that is well-suited for forensic identity testing and other genetic analyses.

Validation of multiplex polymorphic STR amplification sets developed for personal identification applications.

Polymorphic short tandem repeat (STR) loci, which typically consist of variations in the number of 3-7 base pair repeats present at a site, provide an effective means of personal identification. Typing can be accomplished by amplification of genomic DNA using the polymerase chain reaction (PCR) and locus-specific primers, separation of amplified alleles using gel electrophoresis and their display using silver staining or fluorescent detection. Primers for several STR loci can be combined in a single multiplex reaction so typing of multiple loci can be accomplished rapidly and with less DNA than required if each locus were analyzed separately. Before such muliplex systems are used in forensic or paternity applications, it is desirable that they undergo testing for their reliability. This study evaluates the performance of two STR triplex systems, one containing the loci HUMCSF1PO, HUMTPOX, and HUMTH01, and the other containing HUMHPRTB, HUMFESFPS, and HUMVWFA31. Protocols for amplification of these two triplexes, and their corresponding monoplexes, were evaluated for sensitivity of detection, resistance to changes in the annealing temperature of the amplification protocol, and the ability to identify the minority contributor in amplification of mixed samples. In addition, five laboratories determined the alleles of twenty DNA samples, each extracted by one of four different extraction methods. The results illustrate that the two STR triplex systems and the monoplex systems contained within them can be used with as little as 0.25 ng of DNA template. Both triplexes amplified with 100% success using the Perkin Elmer Model 480 thermal cycler. With the GeneAmp 9600 System, the CTT triplex amplified with 100% success and the HFv triplex in 95.6% of attempts. These experiments meet many requirements for use in validation of DNA typing systems for forensic cases and paternity identification.

Multiplex sets for the amplification of polymorphic short tandem repeat loci--silver stain and fluorescence detection.

Multiplex PCR amplification systems were developed using well-characterized, polymorphic short tandem repeat (STR) loci. Eight loci utilized in the multiplex amplifications included HUMCSF1PO, HUMTPOX, HUMTH01, HUMVWFA31, HUMF13A01, HUMFESFPS, HUMBFXIII and HUMLIPOL. From this list, three or four non-overlapping loci were simultaneously amplified, separated by denaturing polyacrylamide gel electrophoresis and visualized using silver stain or fluorescence detection. The multiplex PCR amplification systems offer a non-isotopic method for rapid, simple and accurate analysis of STR loci. This high-throughput method for DNA identification has immediate and valuable application in forensic analysis, paternity determination, tissue culture strain identification and bone marrow transplantation studies.

General approach to analysis of polymorphic short tandem repeat loci.

Polymerase chain reaction amplification products of 22 known polymorphic short tandem repeat (STR) loci were subjected to denaturing polyacrylamide gel electrophoresis and detected using a silver staining method. Loci that amplified efficiently and revealed the fewest amplification-related artifacts with this detection method were selected for development of allelic ladders. The combination of allelic ladders and silver stain detection provides an inexpensive and general non-isotopic analytical method for DNA identification. This approach has immediate application in forensic analysis, paternity determination, human cell line identification and monitoring of bone marrow transplants. It can also be adapted to more general applications of genetic analysis in human and other species including detection of genetic disorders and cancers.

Swiss population data and forensic efficiency values on 3 tetrameric short tandem repeat loci-HUMTH01, TPOX, and CSF1PO-derived using a STR multiplex system.

Allele and genotype frequencies for 3 tetrameric short tandem repeat loci were determined in a Swiss population sample (n = 100) using the GenePrint STR Multiplex System, electrophoresis of the PCR products in DNA sequencing gels and subsequent detection of allelic fragments by silver staining. The loci are HUMTH01, TPOX, and CSF1PO. The observed heterozygosities are 83.0%, 60.0%, and 72.0%, respectively. The discrimination power determined for the individual loci is 0.914, 0.780, and 0.860, respectively, and the combined discrimination power for the triplex is 0.997. All loci meet Hardy-Weinberg expectations and after Bonferroni correction there was no evidence that the population sample deviates from expectations of independence. Moreover, independence of alleles at these STR loci with other PCR-based loci derived from the same Swiss population sample, previously reported, were considered. These loci were DQA1, LDLR, GYPA, HBGG, D7S8, GC and D1S80. Again, after Bonferroni correction there was no evidence that the population sample deviates from expectations of independence among alleles at the 10 different PCR-based loci. Thus, the allelic frequency data can be used in human identity testing to estimate the frequency of a multiple PCR-based DNA profile in the Swiss population.

Allelic ladder characterization of the short tandem repeat polymorphism located in the 5' flanking region to the human coagulation factor XIII A subunit gene.

The short tandem repeat (STR) polymorphism present within the 5' untranslated region of the human coagulation factor XIII A subunit gene, HUMF13A01[AAAG]n, was evaluated using an allelic ladder, i.e., a standard size marker consisting of amplified alleles from the locus. The allelic ladder was constructed by pooling 12 polymerase chain reaction (PCR)-amplified alleles identified by their differential migration in denaturing polyacrylamide gel electrophoresis. This standard marker was used to distinguish 14 different alleles observed at this locus. Sequence analyses indicate that 13 of the alleles contain 4 through 16 iterations of the tandemly repeated AAAG sequence, respectively. The remaining allele carries four repeats and displays a deletion of two consecutive nucleotides (GT), one base distal to the repeat region. The allelic ladder was employed to type 326 F13A01 chromosomes rapidly and reliably in representatives of a German Caucasian population. Population data were analyzed with respect to Hardy-Weinberg Equilibrium (HWE) and compared with those of a previously studied Houston, Texas, Caucasian population.

Identification of repeat sequence heterogeneity at the polymorphic short tandem repeat locus HUMTH01[AATG]n and reassignment of alleles in population analysis by using a locus-specific allelic ladder.

An allelic ladder containing amplified sequences of seven alleles of the polymorphic human tyrosine hydroxylase locus, HUMTH01, was constructed and employed as a standard marker. Sequence analysis of each ladder component indicates that fragments differ by integral multiples of the AATG core repeat sequence characteristic of this locus. Individual alleles are designated "5" through "11," according to the number of complete reiterations of the core repeat contained within them. Comparison of the HUMTH01 allelic ladder with DNA samples amplified at this locus revealed core repeat length heterogeneity (i.e., deletions or insertions shorter than one core repeat) within the human population. In particular, a common allele was identified which migrates more quickly than allele 10, but more slowly than allele 9, on electrophoresis through a denaturing polyacrylamide gel. Sequence analysis of this allele, designated "10-1," reveals lack of a single adenine normally present in the seventh copy of the AATG. The allelic ladder was used to reevaluate previously published population data. Results of testing for Hardy-Weinberg equilibrium and population substructure were not altered significantly by these modifications.

The GenePrint Light method for Southern transfer and chemiluminescent detection of human genomic DNA.

A simple, fast and sensitive method to perform Southern transfer and hybridization with nonradioactive detection of genetic loci is described. With a 10-ng sample of human genomic DNA, alleles of the D2S44 locus can be detected within 7 h of completing gel electrophoresis.

An oligonucleotide probe to assay lysis and DNA hybridization of a diverse set of bacteria.

A computer bank of 16 S rRNA bacterial sequences was searched to determine a consensus sequence expected to hybridize with DNA from a wide variety of bacteria. An oligonucleotide probe, named a panprobe, containing this sequence was used to assay the degree of lysis of bacterial colonies on filter paper heated in a microwave oven and subsequently treated with NaOH. As determined by colony hybridization with the panprobe, lysis was achieved for 51 of 59 different species of bacteria tested. DNA, isolated from the eight bacteria not detected by colony hybridization, did hybridize with the panprobe in slot blot hybridizations.

Identification of more than 500 RFLPs by screening random genomic clones.

As part of our genome-mapping effort, we undertook a large-scale screening study to identify RFLPs useful as genetic markers. Some 1,664 single-copy or repeat-containing phage clones from a Charon 4A genomic library were tested for polymorphism against a panel of DNAs, from five unrelated individuals, digested with eight restriction enzymes. Approximately 30% (515) of the clones revealed polymorphism by Southern hybridization; 67 loci detected had PIC values greater than .5. Restriction enzymes MspI, TaqI, and RsaI were most efficient in detecting polymorphism within the 1-20-kb-fragment size range resolved. With only one exception each of the clones detected polymorphism originating from a single locus.

Use of highly polymorphic DNA probes for genotypic analysis following bone marrow transplantation.

The use of DNA markers known as restriction fragment length polymorphisms is a sensitive and informative method of distinguishing patient and allogeneic donor cells after bone marrow transplantation. To apply the test, it is necessary in each case to find DNA probes that display patient-specific and donor-specific bands in Southern transfer hybridization. We have isolated a set of 12 cloned DNAs from highly polymorphic loci by which siblings can usually be distinguished. With just four of these probes, we can expect to distinguish the genotypes of the recipient and a sibling donor in more than 99% of cases (except between identical twins). The availability of many highly polymorphic probes also allows selection of an optimal probe for each case, one that can detect both the patient and donor-specific bands in a single hybridization with maximum resolution and sensitivity. We have applied these probes to the analysis of cells from peripheral blood and bone marrow after transplantation and demonstrated their usefulness in confirming engraftment of donor cells or graft rejection, and in detecting mixed lympho-hematopoietic chimerism.

Cystic fibrosis locus defined by a genetically linked polymorphic DNA marker.

A polymorphic DNA marker has been found genetically linked, in a set of 39 human families, to an autosomal recessive gene that causes cystic fibrosis (CF), a disease affecting one in 2000 Caucasian children. The DNA marker (called D0CRI-917) is also linked to the PON locus, which by independent evidence is linked to the CF locus. The best estimates of the genetic distances are 5 centimorgans between the DNA marker and PON and 15 centimorgans between the DNA marker and the CF locus, meaning that the location of the disease gene has been narrowed to about 1 percent of the human genome (about 30 million base pairs). Although the data are consistent with the interpretation that a single locus causes cystic fibrosis, the possibility of genetic heterogeneity remains. The discovery of a linked DNA polymorphism is the first step in molecular analysis of the CF gene and its causative role in the disease.

A polymorphic DNA marker linked to cystic fibrosis is located on chromosome 7.

Although cystic fibrosis (CF) is among the most common inherited diseases in Caucasian populations, the basic biochemical defect is not yet known. CF is inherited as an autosomal recessive trait apparently due to mutations in a single gene, whence the efforts made to identify the genetic locus responsible by linkage studies. Two markers have recently been identified that are genetically linked to CF: one is a genetic variation in serum level of activity of the enzyme paraoxonase, and the other is a restriction fragment length polymorphism (RFLP) identified with a randomly isolated DNA probe. We report here that the genetic locus DOCRI-917 defined by the cloned DNA probe is located on chromosome 7.

Molecular cloning and characterization of double-stranded cDNA coding for bovine chymosin.

A full-length cDNA copy of the mRNA encoding calf chymosin (also known as rennin), a proteolytic enzyme with commercial importance in the manufacture of cheese, has been cloned in an f1 bacteriophage vector. The nucleotide sequence of the cDNA was determined, and translation of that sequence into amino acids predicts that the zymogen prochymosin is actually synthesized in vivo as preprochymosin with a 16 amino acid signal peptide. In vitro translation of total poly(A)-enriched RNA from the calf fourth stomach (abomasum) and immunoprecipitation with antichymosin antiserum revealed that a form of chymosin (probably preprochymosin judging from the Mr-value) is the major in vitro translation product of RNA from that tissue. Gel-transfer hybridization of restriction endonuclease-cleaved bovine chromosomal DNA with labeled cDNA probes indicated that the two known forms of chymosin, A and B, must be products of two different alleles of a single chymosin gene.