Simultaneous estimation of a Y-specific fragment, an X-specific fragment and sex determination of forensic studies in real-time PCR.

The human sex test in forensic multiplexes is based on the amelogenin gene on both the X and Y chromosomes commonly used in sex genotyping. In this work sex determination across the quantification of nuclear DNA was achieved by real-time PCR of a segment of the X-Y homologous amelogenin (AMG) gene that allowed the simultaneous estimation of a Y- and an X-specific fragment. The AMG real-time PCR design has been used to quantify a set of forensic casework samples.

Rapid and efficacious real-time quantitative PCR assay for quantitation of human DNA in forensic samples.

A reliable quantification of human DNA is necessary in the process of routine forensic human identification. When DNA is degraded, contaminated or associated with inhibitors, is important to accurately estimate the concentration of extracted DNA prior to perform an analysis based on nuclear markers amplified. In this work, a new approaches to DNA quantification employees the use of a real-time fluorescence probe system. The real-time PCR assay is highly sensitive, specific, rapid, cost-effective and flexible assay for analysis of forensic casework samples, can perform with DNA of poor quality and detect specifically amplifiable DNA rather than total DNA for STR analysis.

Routine clinical application of the FRAXA Pfu PCR assay: limits and utility.

Fragile X genotype is characterized by the excessive amplification of an unstable region of DNA: a trinucleotide repeat CGG of variable copy number present in the FRAXA locus. Methods based on polymerase chain reaction (PCR) amplification of the CGG repeat region could facilitate the development of a rapid screening assay. Unfortunately, amplification across CGG repeats can be inefficient and unreliable due to their 100% G + C base composition. The utility of the exonuclease-deficient Pfu polymerase for amplification and detection of the CGG repeats at the FRAXA locus has been reported. In the present study we analysed the utility of a Pfu PCR assay as a rapid initial screening method to rule out a diagnosis of fragile X syndrome in males with mental retardation. Affected males did not show any amplification products or a smear of amplification products between 350 and 550 bp. Only 10% of affected male samples did not show any amplification products, while the vast majority showed the amplification smear. The amplification smears represent a serious drawback of the method, since they cannot be distinguished from the amplification products of normal samples after separation in 1% agarose gel. Several modifications of the PCR conditions were attempted to eliminate this problem, but none was appropriate for clinical applications. However, the problem was easily solved by using a higher resolution electrophoretic system that allows a clear distinction of normal bands from pathological smears. We tested the specificity of the Pfu PCR assay, followed by an improved MetaPhor gel electrophoretic separation of PCR products, on 50 samples from normal males and 24 samples form affected males. The results showed that this method is a rapid, sensitive and specific assay for the exclusion of fragile X syndrome diagnosis in mentally retarded males.