What is the new gene editing technique?

DEAR DOCTOR K: My son said he learned in school about a powerful new technique for editing genes that could possibly cure diseases. It also sounds a little scary. Can you tell me more?

DEAR READER: Your son probably is talking about a technique called CRISPR. This technique already is having a great impact on biological research, and it may someday help cure some human diseases. Many diseases are caused by defects in how genes are built. This, in turn, can cause a defect in how the protein made by the gene is built.

Will studies of our genes change medicine and improve our lives?

In yesterday's column, a reader asked whether she should be tested for genes linked to Alzheimer's disease. Today, I thought I'd give you my view on the larger question: Will studies of our genes change the practice of medicine and improve our lives?

My answer: During my career, progress in human genetics has been greater than virtually anyone imagined. However, human genetics also has turned out to be much more complicated than people imagined. As a result, we have not moved as rapidly as we had hoped in changing medical practice.

Are older fathers more likely to have children with autism?

DEAR DOCTOR K: I am a 34-year-old woman married to a man more than 20 years my senior. Our first child, a son born four years ago, is autistic. I have heard that older fathers are more likely to have autistic children. Is this true?

DEAR READER: I am not an expert on autism. I have learned what I know from experts here at Harvard Medical School. No one knows the causes of autism, but today the apparent consensus is that they are biological — something a child is born with. As to your question, I'm told that some research has shown that a child's risk of developing autism does rise as the age of the child's biological father rises.