Although the existence of LRRK2 protein in microglia and astrocytes has been reported in the past [24], and LRRK2 variants have been linked through GWAS to Crohn's disease [25,26] and leprosy [27], it was not until 2010 that researchers found that LRRK2 expression is precisely up-regulated by inflammatory signals in myeloid cells, strongly implicating its potential role as a regulator of immune responses [21]. This evidence concerns the gene LRRK2 and Crohn disease.