What Do My ANA Test Reports Indicate?

Hi my name is Stephanie --- and I have had three ANA test in the past. In 2008 the first ANA test came back positive greater than 120. Also, was 184 mixed connective tissue disease. In 2009 second ANA test came back negative less than 120. 2010 it came back positive and the Doctor s comment were as follow:MITOCHONDRIAL PATTERN ANA TITER = 1:640. What does all this mean.. Please advice...