Nature v. Nurture: Can We Influence Our Genetic Language Pathways?

Nature v. Nurture: Can We Influence Our Genetic Language Pathways?

SHARE THIS:Facebooktwitterredditpinterestlinkedinmail

by Stephanie Cook

“When did your child start talking?” When you’re a parent of a toddler, surrounded by other parents of toddlers, this is a question you can’t escape. And the answers are never the same, as we all know that children do things at their own pace – at least within a somewhat similar timeframe. We still worry though if things are wildly different. Who hasn’t secretly thought, “Why is my child not saying anything intelligible yet, while my friend’s daughter speaks in whole sentences?”, or “My son was able to communicate quite clearly at this age, my friend should really worry about hers not even being able to say ‘mom’.” Parenting can be so confusing!

Yes, children develop at different paces, and within a certain framework that is totally normal. Delayed language skills can have a number of reasons, and sometimes they are really only a reflection of our child’s character, or the consequence of growing up with more than one language. Some children simply take a little longer. Sometimes, however, and precisely because of the reasons cited above, we don’t recognize true language impairment until the child is much older. By that point, treatment is often much more difficult, or even impossible. Researchers have now found a specific genetic link between neurological disorders and speech impairment, which gives hope for early detection and subsequent treatment.

There are a myriad of language, communication and speech disorders, the root causes of which are sometimes hard to pinpoint. In fact, those disorders account for 40% of referrals to pediatricians in this country. And while a number of those conditions can be traced to environmental and physical factors such as prenatal exposure to nicotine, hearing loss or brain damage, a more significant amount of disorders are caused by genetic mutations. This is the area that has kept researchers busy over the last few decades, and big discoveries have been made.

In some children, developmental speech or language problems are part of a more comprehensive syndrome such as autism, but in most cases, these impairments occur in the absence of autistic or other behavioral symptoms. Children suffering from dyspraxia, for example, very often have language-related problems, which can lead to learning difficulties, but does not affect their intelligence. The most frequently diagnosed form of developmental language disorder is Specific Language Impairment (SLI), affecting up to 7% of children between the ages of 5 or 6.

Characteristics of SLI:

  • language (production and comprehension) far below age level and IQ
  • non-verbal IQ and other non-linguistic development normal
  • no physical reasons for speech impairment (e.g. hearing loss, environmental deprivation, brain damage)
  • delay in starting to talk; first words at age 2 or later
  • unintelligible or immature production of speech sounds
  • simplified grammar
  • limited vocabulary (active and passive)
  • weak verbal short-term memory (can’t repeat words just heard)
  • difficulties in understanding complex language

SLI in particular, with no other behavioral issues, is both confusing and interesting to study. Researchers have found that in some cases, SLI is caused by a mutation affecting a tiny piece of DNA on a gene on chromosome 7. More research on this particular gene, however, has shown that it is not actually a gene for language, but rather a gene that regulates the activity of other genes, having an effect on the development of many organs, including brain systems important for speech and language. In other cases, no abnormality of that particular gene could be found, so it seems that the disorder is caused by the interaction of several genes, coupled with certain environmental factors.

In 2013, researchers led by Dr. Jeffrey R. Gruen, professor of pediatrics, genetics, and investigative medicine at Yale, analyzed data from more than 10,000 children born in 1991-1992 and found genetic variants that can predispose children to dyslexia and other language impairment. According to Gruen, “These findings are helping us to identify the pathways for fluent reading, the components of those pathways; and how they interact. We now hope to be able to offer a pre-symptomatic diagnostic panel, so we can identify children at risk before they get into trouble at school. Almost three-quarters of these children will be reading at grade level if they get early intervention, and we know that intervention can have a positive lasting effect.”

Last month, the journal Cerebral Cortex published the results of a study conducted by a team of radiologists and psychologists in Philadelphia and San Francisco under the leadership of Timothy P.L. Roberts, PhD, vice chair of Radiology Research at the Children’s Hospital of Philadelphia (CHOP). They based their study on previous research, where they found a mutation on chromosome 16 found that could be linked to neurodevelopmental problems. 115 children took part in the study; 20% had autism spectrum disorder diagnoses. Using magnetoencephalography (MEG), which can detect magnetic fields in the brain, the researchers analyzed the children’s reactions to a series of tones, and found that those children born with certain DNA copy deletions in a specific region on chromosome 16 exhibited a significant delay in processing what they’d heard. According to Dr. Roberts, this study “shows an important connection between gene differences and differences in neurophysiology. It may also help to bridge a largely unexplored gap between genetics and behavior.”

So what does it all mean for us and those of our children affected by genetically caused language problems? While it’s true that genetic mutations cannot be altered, it is a great misconception to believe that genes have a deterministic effect, i.e. nothing can be done to change a child’s predetermined linguistic development. As has been shown through research, even in the case of a strongly genetic disorder, environmental influence can have an effect. “Nurture versus nature”, so to speak, and the more we know about genetic predisposition to certain impairments, the sooner we can intervene with treatment and ultimately alter a child’s developmental path.

Stephanie Cook, originally from Germany, is married to an Englishman, is the mother of two amazing girls, and currently resides in Northern California. She love the multicultural nature of her life and enjoys learning something new every day.

SHARE THIS:Facebooktwitterredditpinterestlinkedinmail