Saliva DNA collection cards are convenient and efficient tools for DNA collection, with a wide range of applications in multiple fields:

I. Forensic Science

1. Crime Scene Investigation
   • Individual Identification
     At crime scenes, saliva of suspects may be left behind, such as on cigarette butts, beverage cups, or bite marks. Saliva DNA collection cards can be used to conveniently collect these saliva samples. Subsequently, the collected DNA samples are compared with those in the suspect database or the victim’s DNA sample, enabling accurate individual identification. For example, in a rape case investigation, saliva DNA is extracted from the crime – scene remnants and matched with the suspect’s DNA, providing crucial evidence for solving the case.
   • Kinship Identification
     Saliva DNA collection cards can also be applied to kinship identification, assisting in resolving cases related to family relationships. For instance, in cases of child abduction, saliva samples from suspected relatives and the abducted child are collected. By testing the DNA on the collection cards, it can be determined whether there is a kinship between them, providing a scientific basis for handling the case and reuniting families.
2. Identification of Disaster Victims
   After large – scale natural disasters (such as earthquakes, tsunamis, fires, etc.) or major accidents (such as plane crashes, mine disasters, etc.), the bodies of victims may be severely damaged, making traditional identification methods (such as through appearance or fingerprints) difficult to implement. At this time, saliva samples of victims (if available) can be collected using saliva DNA collection cards, or items containing their saliva from the victims’ belongings can be used for DNA collection. By comparing with the DNA samples provided by family members, the identities of the victims can be determined, providing strong support for post – disaster handling.

II. Medical Field

1. Disease Diagnosis and Genetic Counseling
   • Single – gene Inherited Disease Detection
     Many single – gene inherited diseases (such as cystic fibrosis, thalassemia, etc.) can be diagnosed by testing the DNA in saliva. Patients or suspected patients only need to spit saliva onto the saliva DNA collection card, providing a convenient source of DNA samples. Then, laboratories use techniques such as gene sequencing on the DNA from the collection cards to determine whether there are pathogenic gene mutations. This is crucial for the early diagnosis and intervention of diseases, especially those that occur in childhood.
   • Assessment of Genetic Susceptibility to Complex Diseases
     For complex diseases caused by the combined effects of genes and environmental factors (such as cardiovascular diseases, diabetes, cancer, etc.), saliva DNA collection cards can be used to collect an individual’s DNA sample to assess their genetic susceptibility to these diseases. Researchers can detect gene polymorphisms related to these diseases. Based on the test results, personalized health advice can be provided to individuals, such as lifestyle adjustments and disease prevention measures.
2. Pharmacogenomics Research and Application
   In the field of pharmacogenomics, saliva DNA collection cards are ideal tools for collecting patients’ DNA samples. By analyzing the DNA in patients’ saliva, information about their drug – metabolizing enzyme genes, drug target genes, and drug transporter genes can be obtained. This can predict patients’ responses to specific drugs, including the efficacy and possible adverse reactions of the drugs. For example, when using drugs like warfarin for treatment, adjusting the drug dosage according to the saliva DNA test results of patients can improve the safety and effectiveness of treatment.

III. Genetic Research

1. Population Genetics Research
   Researchers can use saliva DNA collection cards to collect DNA samples from a large number of individuals for population genetics research. By analyzing the saliva DNA of different populations (such as different ethnic groups or regional populations), aspects such as human genetic diversity, gene frequency distribution, and population migration history can be studied. For example, in the research on the origin and migration of a specific ethnic group, saliva DNA samples of members of this ethnic group are collected. By detecting the distribution of specific genetic markers, the origin and migration routes of their ancestors can be traced.
2. Gene Function Research
   In gene function research, saliva DNA collection cards facilitate the collection of DNA from experimental subjects. For example, when studying the association between certain genes and specific traits (such as height, intelligence, hair color, etc.), saliva DNA from a large number of individuals can be collected, followed by genotyping and association analysis. In addition, when researching the expression regulation of genes under different environmental factors, saliva DNA collection cards can also be used to collect samples for subsequent gene expression analysis and functional verification.

IV. Anthropology and Archaeology

1. Research on Human Origin and Evolution
   Extracting saliva DNA from ancient human remains has always been an important means of studying human origin and evolution. Although it is difficult to directly obtain ancient saliva samples, by collecting possible saliva traces on parts of ancient human teeth and other areas, and using advanced techniques to extract and analyze the DNA from saliva DNA collection cards, the genetic composition of ancient humans, their kinship with modern humans, and the migration and evolution of ancient humans can be understood. For example, in the study of the relationship between Neanderthals and modern humans, saliva DNA that may be present on Neanderthal remains found at archaeological sites is collected and compared with the DNA of modern humans to reveal the gene exchange and integration phenomena in the process of human evolution.
2. Genetic Research on Ancient Populations
   Saliva DNA collection cards also have important applications in the genetic research of ancient populations (such as ancient tribes, ancient civilizations, etc.). By collecting DNA from items that may contain saliva in ancient tombs, ruins, and other archaeological discoveries (such as tableware or mouth – harps in funerary objects), the genetic structure, disease prevalence, and family relationships of ancient populations can be studied. This helps to restore the population structure and living scenes of ancient societies, providing a genetic perspective for archaeological and historical research.