Sjogrens syndrome systemic sclerosis mixed connective tissue disease

Which of the following statements regarding mixed connective tissue disease (MCTD) is most accurate?

1: Anti-U1 ribonucleoprotein antibodies are directly responsible for symptoms associated with MCTD
2: Antimicrosomal antibodies must be present in patients with MCTD
3: MCTD is easily diagnosed based on the presence of several pathognomonic signs
4: MCTD most commonly affects adult women