Genes
Epigenetic modifications, particularly DNA methylation and microRNAs
(miRNAs), might have the potential to identify AR patients. One recent
study has demonstrated changes in DNA methylation in tryptase gamma 1
(TPSG1 ), schlafen (SLFN12 ), and mucin 4 (MUC 4 ),
following controlled allergen challenge, and suggested that baseline
epigenetic status may act as a potential biomarker for AR symptom
severity.84 Another recent study has indicated that
nasal epigenome associated with asthma, FeNO and IgE may serve as a
sensitive biomarker of asthma, allergy and airway inflammation in
children.85 Other studies have reported that subsets
of circulating miRNAs are solely expressed in the blood of patients with
AR and asthmatics and may therefore be used as non-invasive biomarkers
for diagnosis and characterization of these
diseases.86,87
Metabolites
Metabolites have also been proposed as biomarkers for AR. A very recent
study of serum metabolomics has demonstrated that at least nine
metabolites (13(S)-HPODE, bilirubin, leukotriene D4, hypoxanthine,
L-stercobilinogen, N-succinyl-L-diaminopimelic acid, chlorophyll b,
15-hydroxyeicosatetraenoic acid, and urate) were significantly altered
in the serum of AR patients, and therefore may provide a better
understanding of the metabolic pathways involved in the aetiology of
AR.88 Additionally, decreased serum lactoferrin level
has been reported to be associated with the phenotype ofDermatophagoides pteronyssinus (Der p1 )-sensitive AR, and
in combination with serum Der p1 -specific IgE level, may serve as
a serologic biomarker for early detection of AR.89