QUESTION: My nephew has Tourette's syndrome. He had tics early on, but my sister never suspected anything. She took him in later to a specialist. She confirmed Tourette's. I haven't spoken to my sister about this lately, since she lives quite a distance. Her letters are confusing. Please explain a bit about this problem. - V.K.

ANSWER: Tics, involuntary repetitive muscle movements, are quite common in children. Some estimate that as many as 25 percent of children may have tics of one kind or another. Most disappear, and the less attention devoted to them the better. Most disappear in a year. Tourette's is different.While much progress has been made in treating Tourette's, little is known, really, about the cause. It appears to be a disruption of nerve pathways affecting nerve chemical transmission. In Tourette's, the tic appears at between 6 to 7 years on average and persists, waxing and waning in intensity. The pattern may eventually include vocal grunts and actual sudden involuntary verbalizations.

Some attention has been given to potential inherited factors, but no one can be entirely certain on this point. Tourette's often does run in families. And the spectrum of severity of the problem is so broad that some member may have had it and never realized it.

The bottom line here is treatment. There is much help available. When the symptoms do not subside with years, there are a number of medicines to be tried. To some degree at least the mere calming influence of a caring parent works wonders.

QUESTION: I don't know what's wrong with me. I burst into tears at the slightest provocation. Do you know of people like me? I have been like this all my life. Do you think I am sick? - Mrs. P.B.

ANSWER: You are not a rare bird. Inappropriate crying can have its roots in the genes. Or it can represent a psychological or a neurological problem.

I wish you had given your age. You do tell me you have been this way all your life, which makes me lean toward an inheritance factor. Do relatives recall this occurring in past generations?

Now there are special cases. I am thinking of persons who have had a stroke and for whom such crying can represent loss of the brain's control of emotional responses.

I'm at a loss as to what to advise. If your crying is an embarrassment, you might want to attempt behavior-modification therapy to gain some degree of control. A psychologist might be able to help.

QUESTION: My sister has borderline diabetes. She is having trouble keeping her blood sugar on an even keel. She is on some kind of pill for it. She has sweats. I wonder if it's her diet? I presume even borderline diabetics need a diet. - I.T.

ANSWER: If your sister is having trouble controlling her blood sugar levels, she's gone over the line of borderline diabetes. I suspect the pill she's taking is one that lowers blood sugar. If so, it might be doing that too aggressively. That can cause sweating. So that's one consideration to investigate.

Or perhaps the pill is OK, but she does not understand the ins and outs of a diabetic diet, which is as important for a borderline as for more severe diabetes. Diet is not just a nicety for diabetics, but an absolute bedrock necessity. And it is more than sugar avoidance. I am sure that with proper dietary guidance she can keep her sugar situation in hand. But she does need expert help.

Treating Asthma requires understanding the disease itself. For a copy of my new pamphlet No. 41, write Dr. Donohue/No. 41, P.O. Box 830, Gibbstown, NJ 08027-9909. Enclose a long, stamped (52 cents), self-addressed envelope and $2.

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.