Microchimerism: The mystery of multiple DNA and its implications in forensic sciences

Microchimerism (MC) refers to the presence of small amounts of foreign cells or DNA in the tissues or circulation of an individual. It generally occurs through mother-fetus interaction, twin pregnancies, and intergenerational transmission. MC is influenced by genetic and environmental factors such as toxic conditions, immunological suppression, and various diseases (influenza, COVID-19, etc.). Progenitor cells transferred from the fetus to the mother through fetal MC are known to differentiate into neurons in the maternal brain. Although the relationship between these cells and the brain is not fully understood, it is thought that they may play a role in the emergence of some mental illnesses. The long-term presence of microchimeric cells in the body by differentiating into various cell types such as the brain, heart, bone, liver, and lung can lead to the presence of two or more DNA sets in an individual. This can lead to confusion in forensic identification and sex determination processes. This review aims to provide a comprehensive review of the definition, transmission pathways, detection duration in the human body, associated diseases, analytical detection techniques, and the importance of MC in forensic sciences. In this context, it is aimed to draw attention to the potential dangers of MC and contribute to the justice system. Furthermore, this study emphasizes the need for scientific research on this topic by creating a starting point for future research in the field of MC.