Other conditions in this group, with different phenotypes include: monogenic systemic lupus erythematous (TREX1, SAMHD1 genes), ISG15 deficiency (ISG15 gene), Singleton-Merten syndrome (IFIH1 gene), trichohepatoenteric syndrome (SKIV2L gene), X-linked reticulate pigmentary disorder (POLA1 gene), STING- associated vasculopathy of infancy (TMEM173 and STING genes) and COPA (COPA gene) (105, 114). The gene discussed is ISG15; the disease is trichohepatoenteric syndrome.