H19 and periodontitis: The difference of LncRNA H19 SNP distribution between the two gender subgroups may be due to the existence of expression quantitative trait loci which lead to gender-difference expression of LncRNA inter chr4 3011 in mice [46] and the possible difference function of EGFR pathway between gender, which is found in the kidney mouse [47], may also cause such gender difference as the expression of LncRNA PACER in periodontitis [48].