How life difficulties can affect children's DNA

A "Jeopardy" answer: The word for the plastic tip of a shoelace.

Question: What is an aglet?

A medical jeopardy answer: The word for the DNA at the ends of chromosomes.

Question: What is telomere?

In my office at St. Christopher's Hospital for Children last month, I saw a small 9-year-old boy for a checkup before fourth grade. His single mother was concerned that a child was repeatedly bullying him at school. She also worried about having enough food to last the month. The boy had lived with his grandparents while his mother was recovering from drug addiction and obtaining her GED.

As I used the medical tools in the exam room, my stethoscope and otoscope, I reassured his mother his physical exam was perfect.

But was it?

Like the plastic aglets on the ends of shoelaces that keep them from unraveling, telomeres protect the genetic data organized in the beautiful twisted double helix that makes up our DNA - the blueprint of our lives. Telomeres, when functioning correctly, keep chromosomes from fraying and sticking to one another. Telomeres are mortal; they get shorter each time a cell divides until it can't divide anymore, and dies.

In 2009, the Nobel Prize in medicine went to three American researchers who isolated and explained the function of telomeres and their involvement in human disease and aging. Research on telomeres is expanding throughout medicine.

Dyskeratosis congenita is an extreme example of a rare disease caused by telomere dysfunction. Patients experience premature graying, an extremely high risk of cancer, and other abnormalities that resemble early aging. Those with the severe form usually die before age 20 from cancer or bone-marrow failure.

Research on adults has shown patients with shorter telomeres are three times more likely to die from heart disease and eight times more likely to die from infectious diseases. Another study showed people with shorter telomeres died five years sooner than those with longer ones. Telomere shortening has been linked to cancer, compromised immune function, poor mental health, diabetes, and obesity. When it comes to telomeres, size does matter.

What about children? Several recent studies, including one published this summer in the journal Pediatrics, demonstrate once again the link between adverse childhood experiences and health. But the recent studies probe deeply into the cellular level, looking at the crucial tips of chromosomes, the telomeres.

The Pediatrics study, "The Association of Telomere Length with Family Violence and Disruption," measured telomeres in children ages 5 to 15 in New Orleans. Those who had witnessed family violence, experienced a family member's suicide, or knew a family member who was incarcerated had shorter telomeres. Another study found shorter telomeres in adults who were maltreated as children.

Another examined life events and telomere length in 9-year-olds. It determined that children of mothers who changed partners more than once had 40 percent shorter telomeres. Children whose mothers didn't finish high school had 32 percent shorter telomeres. Harsh parenting, teen mothers, and childhood poverty (now at 25 percent of all children under 5) also had significant negative effects on telomere length, demonstrating how early life stressors prematurely age young genes.

The news isn't all bad. A Duke University study showed that if children in a previously abusive environment don't experience abuse after age 5, they regain some of their lost telomere length. And if pediatricians, parents, politicians, and child advocates focus their efforts on programs to strengthen families in children's early years, we can halt or even prevent the catastrophic time bomb of telomere shortening.

Programs such as the Nurse-Family Partnership and Early Head Start have been shown to help decrease the stressors on high-risk families. Reducing childhood poverty and its ill effects also must be a national priority.

Last month, as I discussed safety, bullying prevention, and emergency food resources with the mother of my patient, I realized I wasn't being completely honest with her. The physical exam most likely was not perfect. On a cellular level, the child's telomeres probably were shortened.

As he dressed and hastily put his feet into his sneakers, I glimpsed the tip of a shoelace. The aglet was missing; the shoelace was unraveling. I breathed deeply, wishing I had new shoelaces to give him.