BTG3 and Down syndrome: BUN: blood urea nitrogen; AST: aspartate aminotransferase; ALT: alanine aminotransferase; ALP: alkaline phosphatase; LDH: lactate dehydrogenase; ANA: antinuclear antibody; anti-dsDNA: anti–double-stranded DNA antibody; ANCA: antineutrophil cytoplasmic antibody; anti-SSA/Ro: anti–Sjogren’s syndrome-related antigen A/Ro antibody; anti-SSB/La: anti–Sjogren’s syndrome-related antigen B/La antibody; anti-Sm: anti-Smith antibody; anti-RNP: anti–ribonucleoprotein antibody; C3: complement component 3; C4: complement component 4