DEAR DR. DONOHUE: I wonder if you might discuss adult polycystic kidney disease, which seems to run in my wife's family. Is it really inherited? How serious is this? Are there early signs of it in a person? Should our children be checked for it? Thanks. - J.L.

ANSWER: This particular kidney disease is inherited. Its chief distinguishing peculiarity is the adult onset. It is usually in late middle age when the cyst problem worsens to cause kidney enlargement.Blood pressure rise is almost always a part of adult polycystic kidney disease. In fact, elevated blood pressure can be one of the early clues to its presence. Evidence of blood in the urine and flank pain are other common signs.

Eventually, the continuing cyst enlargement may destroy normal kidney tissue, with resulting loss of its blood-filtering function, a very serious development, to be sure. Should that happen (and it doesn't always) artificial blood cleansing (dialysis) or kidney transplantation is done.

The usual rule for children of parents who have adult polycystic kidney disease is to be examined for the illness in their early 30s. The cyst problem can be detected then with an ultrasound examination. (The cysts are usually not visible until then.)

Again, let me stress that I have been speaking here exclusively of adult polycystic kidney disease and not of the many other forms of such kidney cyst problems.

DEAR DR. DONOHUE: The doctor told me I have mild dysplasia and that he would have to cauterize it. Can you explain dysplasia and what cauterizing will do? Please tell me if this is an inherited illness or sexually transmitted, also if there are cancer risks involved, and if it could affect sexual partners. What of the future? - T.

ANSWER: Your Pap smear showed cells that looked abnormal (dysplastic). The cells are not malignant, but if left alone and not treated could become so. Cauterizing the tissue destroys these cells to remove the cancer potential.

Dysplasia is not inherited, and what gives rise to it often cannot be shown. You have heard of genital warts, haven't you? They cause dysplastic changes. Such warts are sexually transmitted, so your sexual partners should be informed and examined if warts played a role in your dysplasia.

What happens in the future depends on what is done today. Your doctor has taken the first step, the cauterization. You should be rechecked from time to time over the next year to be certain all dysplastic tissue has gone. If it has, then so should your worries.- Troubled by acne? Dr. Donohue's booklet No. 39 can help. For a copy of "Dealing with Acne," write Dr. Donohue/No. 39, P.O. Box 830, Gibbstown, NJ 08027-9909. Enclose a long, double-stamped, self-addressed envelope and $2.00.

Dr. Donohue welcomes reader mail but regrets that, due to the tremendous volume received daily, he is unable to answer individual letters. Readers' questions are incorporated in his column whenever possible.