Does DNA Deteriorate?

I received an interesting question via e-mail that I would like to share with you. The writer asks,


“Does the genetic information in DNA start to break down after a certain age?” The writer also asked if children produced from the union between a younger female and older male would have more maternal characteristics because of her younger age.


In reference to the first question, DNA can change with age. Human chromosomes, composed of DNA, have a particular structure. The tip of each chromosome end is called the telomere and it is believed that a shortening of the telomere is an important event in the aging process.


As to the second question, parental age is not a factor in determining the physical features of a child. However, we do know that there are increased risks for new mutations and chromosomal abnormalities associated with both advanced maternal and paternal ages.


Advanced maternal age is much better studied and documented through screening procedures and test analyses. Advanced maternal age is considered age 35 and above. It is from this point that increased risk for having a child with Down syndrome or another chromosomal condition exists.


Advanced paternal age is more difficult to determine. Literature references range from 45 to 55. It is known, however, that new single gene mutations can increase with advancing paternal age. What do we mean by “new mutation”?


In many autosomal dominant disorders, an affected individual will usually have a similarly affected parent. Sometimes, a new mutation can occur resulting in an affected individual with no family history for the disorder. An example of this is achondroplasia or genetic short stature. Achondroplasia, with no prior family occurrence, could be the result of a new mutation associated with advanced paternal age. Marfan syndrome which we discussed last month, also has an association with advanced paternal age. It is known that the risk of producing a child with Marfan is approximately 5 times greater for a male over the age of 40.


The basis for these occurrences and risks lies in the biological processes that result in the production of the egg and sperm. We will have to save those discussions for another article!


I appreciate very much your question.