I recently finished Carl Zimmer’s doorstop of a book on heredity. It was an outstanding history of genetic research, told through a series of discrete anecdotes that illustrates how far we’ve come (and how far we have to go) in understanding the mechanics of genetic inheritance. One chapter was particularly interesting to me, and I’d like to share the story here because of the implications it has for a contextual approach to therapy.
The Pulitzer Prize-winning author Pearl Buck gave birth to a daughter named Carol in 1920. When she was born, the child had eczema and her skin emitted a musty odor. As she grew older, Carol didn’t learn to talk like other children do and she began to exhibit other developmental delays. Eventually, doctors told Pearl that Carol “will never be well.” Based on that diagnosis, Pearl made the excruciating decision to place Carol at the Vineland Training School, an institution in New Jersey for the “feebleminded.” As Carol grew older, she learned to use words to communicate her needs and was able to bathe and dress herself, but she remained institutionalized for the rest of her life.
Meanwhile, in the 1950s doctors in Norway and Great Britain were working with children who presented with similar symptoms, including that telltale musty smell. In conducting tests, one doctor noticed the patient’s urine was loaded with a chemical compound known as phenylpyruvic acid. The doctors hypothesized that this acid was the result of a buildup of an amino acid called phenylalanine in the patients’ bloodstream. We all get phenylalanine from our food and it’s an essential part of how our body builds necessary proteins—but we only need so much of it, so when we have too much, a particular enzyme in our liver helps to break it down and flush it from our system. For some reason, these children were missing the enzyme, which prevented them from breaking it down. This buildup was responsible for the developmental delays that Carol and the other patients were experiencing. Eventually scientists found a single recessive gene responsible for the broken enzyme and gave the disease a name: phenylketonuria, or PKU.
By isolating the gene responsible, scientists confirmed that this disease is hereditary. However, doctors found that they could mitigate symptoms or prevent them entirely by changing the patient’s diet: by consuming a diet low in phenylalanine, the patients never got more than their body could process. Within a few months of changing diet, one young patient began to walk for the first time, her brain functioning improved, and even her musty smell disappeared. By 1973, nearly all American children were being screened at birth for PKU (the first disease for which widespread newborn screening was implemented) and treatments were created that enabled people with PKU to live vastly different lives—in 2001, a woman named Tracy Beck became the first person with PKU to gain a PhD (in astronomy, no less).
This story stood out to me for two reasons. First, I drink a lot of Diet Coke, and I’ve always wondered why there is a warning on the can. More importantly, I think this story speaks to the limitations of a purely gene-based understanding of disease. While the advances in genetic research that occurred in the mid-20th century allowed for a precise etiological understanding of PKU and also suggested a path forward for treatment, it goes too far to suggest that a gene “is” a disease—as Zimmer notes, “[g]enes don’t have so much power.” While Carol Buck and Tracy Beck both have the PKU gene, the effect of the gene on their life is different due to contextual factors outside their genetic code. In other words: environment matters.
This connects to all sorts of important stuff, like the emerging research we have on the impact of childhood trauma on long-term health outcomes. (See Nadine Burke Harris’ excellent book or TED talk for more information.) It also connects with how I, as an ACT therapist place a premium on identifying contextual factors in a person’s life that may be creating, contributing to, or perpetuating unworkable behaviors. While some doctors or therapists might focus on identifying biomedical explanations for a person’s apparent symptomology, an ACT therapist will focus on identifying and manipulating contextual variables that may be within our sphere of influence. That doesn’t mean that neurological or other biological explanations aren’t important in understanding mental or emotional well-being: only that understanding a person’s context can open new opportunities for growth and change.
References
Zimmer, C. (2018). She has her mother’s laugh: The powers, perversions, and potential of heredity. New York: Dutton.