New perspectives of human saliva as genetic biomarker in early disease diagnostics

Abstract

Saliva is an easily obtainable biofluid rich in genetic biomarkers that can aid in predicting and diagnosing various diseases. Salivary DNA serves as a reliable diagnostic marker, with DNA yield quality from saliva comparable to that from blood and urine, making it suitable for genetic and molecular analysis. Beyond DNA, salivary RNA can also act as genetic biomarkers for conditions such as oral squamous cell carcinoma and other diseases. Currently, noncoding RNAs in saliva, including microRNAs (miRNAs), small nucleolar RNAs (snoRNAs), circular RNAs (circRNAs), and piwi-interacting RNAs (piRNAs), are recognized as potential disease markers. The small size and stability of these molecules in different body fluids, including saliva, provide advantages in molecular diagnostics. For example, salivary 8-OHdG can be used to measure DNA damage and assess disease progression, such as the transition from oral premalignant disorders to oral cancer. Salivary diagnostics is an emerging field, and its integration with genomics facilitates the early detection of various diseases. These genomic components of saliva offer a timely, cost-effective, and non-invasive diagnostic medium. This review aims to explore the genetic biomarkers present in saliva for various diseases.