noonans syndrome

I took my now 6 1/2 year old to see a genetics doctor...I have a disease called NEUROFIBROMATOSIS  he has me as one character of having it and has 5 CAL marks and needs to have 6 to get the official diagnoses.. he was genetically tested but came back negative, (95%) right on 5 % can be a false neg.. i am not sure if mine will come back like his or not, i was diagnosed clinically and biopsy.

now when telling the genteic doctor my sons medical history and he was reviewing his records, he mentioned the word noonans.. I saw a different doctor for me to get tested right away the one my son saw is booking quite a bit far out but they are in the same office and we had the same counselor  now I talked to her about my son and even showed a picture of my son to her she totally agreed that he most likely has noonans...
how long does the test take to get the results back and how accurate are they
Thank you
Michelle