Candace Special is patiently answering Esther Berko’s questions as the two women sit across from one another in the family waiting room of the Cognitive Neurophysiology Laboratory at Albert Einstein College of Medicine, in New York City. Berko is an M.D./Ph.D. candidate in the laboratory of geneticist John Greally, Ph.D. There, thanks to a Dennis Weatherstone Predoctoral Fellowship from Autism Speaks, Berko is searching for clues to the increased risk of autism seen among the children of older mothers.
Special’s oldest son, Chad, age 12, has autism. She was 36 years old when Chad was born. Chad’s father was 34, she tells Berko. No, they didn’t use any assisted reproductive technologies. Yes, Chad has a sibling. A younger brother, age four. No, his brother doesn’t have autism. No, no one else in the family has autism. “Oh wait, yes,” she remembers. “Chad has a cousin who probably has Asperger syndrome.”
Board games, books and puzzles clutter the waiting room. A handwritten sign reads “Welcome Kids.” On a table is a binder titled, “My Day at the Brain Lab.” It begins: This is my brain. It is in my head! Coming to the brain lab will help scientists understand how my brain works.
Special first brought Chad to the medical school’s brain lab when he was 12 because she was having trouble getting her family’s insurance provider to cover the neurological and behavior exams that Chad needed to qualify for special services at school. By enrolling in a research program, she learned, her son could get the exams for free. A year later, they continue to participate in the lab’s research because they enjoy the visits. “It’s really nice to be in an environment where people understand his disability,” she says. “Chad’s been having a blast.”
Berko’s study is a new project for this mom and son. The evaluation involves neither Chad’s brain nor his behavior – not directly anyway. Berko works in the college’s genetics department, just a short walk across campus. She has come to take samples of cells from inside Chad’s cheek while he participates in a separate, neurological study. The bright red, sensor-studded cap on Chad’s head is recording his brain’s electrical activity.
Berko swabs Chad’s mouth with a long, thin brush. “Kids like it ‘cause it tickles them,” she says, then takes a few more swabs and plops the brushes, one by one, inside an array of orange-lidded test tubes.
Berko will take the cheek cell samples back to her lab, where she will preserve and store them in a freezer alongside those of other children, both with and without autism, born to moms ages 35 and older.
Berko is using the cell samples to look for difficult-to-detect genetic changes known as “covert aneuploidy.” Aneuploidy refers to an abnormal number of chromosomes in a cell. (Chromosomes are the cell structures that contain our genes.) Sometimes these abnormalities are hidden, or “covert,” because they’re present in some cells but not others.
Previous research has associated aneuploidy with children of older mothers. Having an older mother, in turn, is associated with increased risk of having a child with autism. Is there a link?
Berko is hoping to find answers by studying cheek cells. These cells are more closely related to brain cells than are cells from other easily obtained tissues such as blood. So they may enable Berko to better detect aneuploidy affecting brain development.
If these variations turn out to be more common in children with autism, she says, they may help explain why autism rates are as much as 30 percent higher in children born to mothers 35 and older when compared to children born to moms in their twenties.
That “why” is a huge question. A wealth of research has confirmed that autism prevalence goes up dramatically among children born to older mothers or older fathers. In addition, several studies have found that kids with autism born to older fathers have higher rates of spontaneous gene mutations. These may arise in the father’s sperm cells before conception. However, until Berko took on her cheek swab project with support from her Weatherstone fellowship, no one had closely looked for genetic changes associated with older moms.
“I don’t know anybody else who would have been able to pull off this study,” Dr. Greally says of his student and colleague. Berko’s study could provide the first step toward a breakthrough in our understanding of some forms of autism, he continues. With few exceptions, every cell in the human body contains enormously long strands of DNA tightly packaged into 23 pairs of chromosomes. At conception, an embryo inherits one set of 23 chromosomes from the mother, the other from the father. But every so often, this process goes awry.
Some problems originate in a mother’s egg. Unlike men, who replace old sperm cells every couple of months, a woman may be born with her lifetime of egg cells. Before puberty, her eggs each have two sets of chromosomes, much like other cells in her body. After puberty, one egg cell divides every month or so. As it does, the chromosome pairs split apart. One chromosome from each pair migrates to each new egg cell. One of these newly matured eggs then leaves the ovary and can be fertilized.
However, as a woman ages, the proteins tethering her egg’s chromosomes weaken. In some cases, the chromosomes break apart. When this happens, the chromosomes don’t align properly when the cell divides. One mature egg may end up with too few chromosomes. The other may receive too many. If an egg with too many or too few chromosomes gets fertilized, problems can result.
Most often, an embryo with extra chromosomes simply fails to develop. If it does develop, the baby may be born with severe disabilities. A baby with three copies of chromosome 21, for example, is born with Down’s syndrome.
Extra chromosome copies can also cause more subtle problems. This occurs, for example, when embryonic cells try to correct the mistake. Some of the early embryonic cells may kick out the extra chromosomes. But not all cells are successful. So as the embryo grows, its cells take on a mosaic quality. Some have two copies of a chromosome. Others have three. This genetic mosaicism can occur in typically developing individuals. Research suggests it’s more common in those conceived through in vitro fertilization, Berko explains.
“It’s quite possible that mosaicism is abnormally common in the brain tissue of some – perhaps many – children with autism,” Berko says. If so, it could explain why some parts of the brain develop typically in people with autism while other parts of the brain develop less typically. Because these changes don’t occur in all of the person’s cells, they are also difficult to detect with standard genetic testing.
When she started her research in Dr. Greally’s lab, Berko had just finished her second year of medical school at Einstein. She was beginning her work toward a joint doctoral degree in medicine and medical research. She was already one of just 170 American students annually selected to participate in the highly competitive Medical Scientist Training Programs. The National Institute of General Medical Sciences funds these programs, of which there are only 40 nationwide. They train scientist-doctors in the art of translating laboratory discoveries into effective treatments for patients.
Then she applied for and received her Autism Speaks predoctoral fellowship. An ongoing program, the Dennis Weatherstone Predoctoral Fellowship encourages promising young scientists to make autism research their chosen career. It is awarded not only on the merits of the candidate’s proposed two-year research project. It also considers the opportunity for mentorship by a world-class researcher such as Dr. Greally.
Dr. Greally is renowned for his pioneering work in epigenetics. This field of study considers the environmental influences that can “dial up” or “dial down” a gene’s activity. By “environmental,” researchers mean just about any non-genetic influence. These include factors such as parental age and prematurity, not just exposure to chemicals or other toxins in the environment.
For a predoctoral student, starting an entirely new line of research was a huge undertaking. And Berko, now 28, had just given birth to her first daughter that summer. “I had every reason to choose a simpler subject for my thesis,” she admits. “But I thought, how can I pass up the opportunity to figure out a piece of the puzzle that we’re completely missing?”
Growing up in Queens, New York, with her father practicing internal medicine, Berko spent time in the hospital where he worked. She witnessed firsthand the gratitude of the patients in his care.
“I thought, this is what I should do with my life as well,” Berko says. “But I also wanted to contribute to the advancement of knowledge. I love the idea of taking a really big question and discovering something new that hasn’t been discovered before.”
Plus, she adds, she was passionate about her chosen project.
Berko’s familiarity with autism came recently. In the fall of 2007, she attended a lecture by Einstein professor Isabelle Rapin, M.D., a famous neurologist and early autism research pioneer. At the lecture, Dr. Rapin talked about regressive autism. These babies develop typically for about two years before losing social and sensory skills.
“I was very bothered by it,” Berko recalls. “It really struck me that you could have this phenomenon where a kid would acquire certain developmental milestones then lose them. It’s terrible. I can’t imagine being a parent and having your child start talking and then, god forbid, they stop.”
When Dr. Greally, her thesis advisor, suggested she study the maternal genetic influences on autism, Berko jumped on the opportunity. She spent a year preparing – learning techniques, developing protocols and taking an advanced statistics course that taught her how to extract meaningful results from large pools of genetic data. Two years ago, she began recruiting patients.
Recently, Berko finished collecting cheek swabs and analyzing the DNA of 50 kids with autism and 50 kids without. She is now studying the data.
“If we see any connections, we will have a reasonable foundation for doing a larger study,” Dr. Greally says.
Berko's has made her acutely aware of the reproductive risks associated with aging, she says, as well as the fact that having children at a young age is simply not an option for millions of parents. She expresses hope that her work will deepen our understanding of autism in ways that will lead to better treatments or preventative measures for all parents.
“I’m grateful,” she says, “that Autism Speaks recognized the validity of this project and was willing to invest in us.” She is also grateful for families like the Specials who give up their time, information and sometimes their own tissues to help scientists better understand this disorder that affects their lives and their loved ones. “I mean, they let us take their cells!” Berko says. “It’s amazing. Their devotion to research is what allows us to move forward.”
Explore more of Autism Speaks career-launching fellowship projects here. You may also enjoy these recent feature profiles of families and scientists advancing autism research: “Sina’s Last Gift” and “Hunting for Autism’s Earliest Clues.”
Photos by Ariel Bleicher unless otherwise indicated.