[Familial chilblain lupus : Type 1 interferonopathy with model character]

Familial chilblain lupus belongs to the group of type 1 interferonopathies and is particularly characterized by typical skin manifestations and ischemia of the acra. There are various mutations that can lead to this autosomal dominant disease. A mutation in the TREX-1 gene has been most frequently found; however, families with mutations in the SAMHD1 gene and recently in the gene which codes for the stimulator of interferon genes (STING) protein were also described. A common feature of these genetic defects is that they are all involved in the process of detection of intracellular free DNA, which as a result leads to increased production of type 1 interferons and the induced gene products. This then leads to autoinflammation and autoimmunity, which is characteristic for the disease. The activation of interferon-induced genes is controlled by the JAK-STAT system; therefore, JAK inhibitors were successfully used in several cases to treat type 1 interferonopathies. Experience with this treatment modality is continuously growing.