MPO and Down syndrome: Tests for anti-Sjögren syndrome A (anti-SSA/La), anti-Sm, anti-double stranded DNA (anti-dsDNA), anti-ribonnucleoprotein (anti-RNP), ani-Scl70, anti-phospholipid, anti-Jo-1, anti-myeloperoxidase antineutrophil cytoplasmic antibody (anti-MPO-ANCA), rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibody, hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), IgG, IgA, IgM, C3, and C4 were negative or normal.