A method to detect a biomarker in saliva wherein the biomarker is an extracellular mRNA, comprises detecting the extracellular mRNA in the cell-free saliva； transcriptome analysis of saliva comprises detecting a transcriptome pattern in the cell-free saliva； a method to detect genetic alterations in an organ or in a gene in the organ by analyzing saliva, comprises detecting a transcriptome pattern and/or the mRNA profiling of the gene in cell-free saliva； a method to diagnose an oral or systemic pathology disease or disorder in a subject, comprises: detecting profile of a biomarker associated with the pathology disease or disorder, in particular mRNA and/or protein, in cell-free saliva and/or serum； kits comprising identifier for at least one biomarker for performing at least one of the methods； and use of salivary biomarker salivary and/or serum mRNAs as biomarkers for oral and/or systemic pathology, disease or disorder.
