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Autosomal STR Reference Standard
Background
STR (Short Tandem Repeat) refers to a special pattern in DNA sequence, that is, a string of short nucleotide sequences are repeated. Since each individual's STR sequence is unique, they can be used as genetic markers for individual identification. STR typing detection technology is widely used in forensic medicine, anthropology, biology and other fields. Its main function is to be used for individual identification, paternity testing, and genetic susceptibility research of diseases.
In terms of individual identification, STR testing is widely used in the field of forensic medicine, such as criminal investigation, identification of missing persons, and identification of disaster remains. At the same time, STR testing is also the gold standard method for paternity testing, and its accuracy and reliability have been widely recognized.
In the study of animal and plant population genetics, STR analysis can be used to study the genetic diversity, inbreeding and genetic drift of animal and plant populations.
At present, the most widely used application of STR is still cell identification. In 2011, the American National Standards Institute issued a special cell STR identification standard, and the ChP (Pharmacopoeia of the People's Republic of China) also stipulates STR tests for cell line quality control. STR genotyping has been used as the gold standard for cell identification by authoritative organizations such as ICLAC and ATCC.
Definition of an Autosomal STR Standard
A stable and reliable DNA sample with known precise typing results for all autosomal STR loci. It is typically derived from a rigorously authenticated cell line to ensure absolute genotyping accuracy and unlimited replicability.
The core functions of an autosomal STR standard are:
*Quality Control: Standards must be run concurrently with DNA testing experiments. If the results of the standard differ from the known values, this indicates a problem with the experimental process (e.g., DNA extraction, PCR amplification, electrophoresis), and all test results for that sample are unreliable and must be repeated.
*Data Comparison Calibration: It provides a unified benchmark for DNA data comparison within and between laboratories globally, ensuring that "[GATA]8" measured in Zhang San's laboratory and "[GATA]8" measured in Li Si's laboratory are identical, thus enabling data sharing and interoperability.
STR Identification Method Principle
STR identification uses PCR (polymerase chain reaction) technology to amplify specific STR sites, and then separates amplified fragments of different lengths by electrophoresis. Since different individuals have different numbers of repetitions at specific STR sites, the lengths of the amplified fragments generated are also different. By comparing these lengths, the genetic characteristics of the individual can be determined, and then a certain calculation method can be used to obtain the STR typing results.
Application Scenarios
The primary application of autosomal STR standards and their detection technology is in forensics and paternity testing, followed by other areas of identity verification.
1.Forensic Identification - Core Applications
*On-site Biological Sample Comparison: DNA is extracted from samples collected at the crime scene, such as blood, semen, hair, and saliva, and then STR profiled. This DNA is then compared with the suspect's STR profile. A successful match provides strong evidence to solve the case.
*Unidentified Body Identification: STR profiles of unidentified remains are entered into a DNA database and compared with the DNA of the missing person's family, enabling identification.
*Database Construction: Countries around the world have established extensive criminal DNA databases (such as the CODIS system in the United States). All data is based on a core set of autosomal STR loci. Standards ensure the accuracy of these data storage and comparisons.
2.Paternity Testing
A child's STR alleles are half paternal and half maternal. By comparing the STR profiles of three individuals, biological parentage can be confirmed or ruled out with greater than 99.99% accuracy. This is currently the gold standard.
3.Other Identification Fields
*Disaster Victim Identification: In major disasters such as plane crashes, tsunamis, and fires, it is often difficult to identify the remains by appearance. STR DNA testing is the most reliable means of identifying victims. Standards ensure the reliability of this process.
*Stem Cell Line Authentication: In scientific research, STR profiling is frequently used to confirm the identity of cell lines and prevent contamination or mix-up. The American Advanced Tissue Culture Collection (ATCC) provides STR profiles for the cell lines it sells.
*Preimplantation Genetic Diagnosis (PGD) in IVF: STR analysis is sometimes used to simultaneously screen embryos for genetic diseases and confirm paternity (to prevent misidentification of embryos).
