In JIA-patients, presence of Abs to HC3 and LC3 peptides resulted in a strong correlation with the disease activity expressed as Juvenile Arthritis Disease Activity Score with 10 joint count (JADAS-10) score at the time of blood sample collection (rs = 0.57, p = 0.02), as well as Abs reacting to HC2 (rs = 0.63, p = 0.006), as reported in Table 3. Here, MAP1LC3A is linked to arthritic joint disease.