How do your two specialties—neurology and clinical genetics—complement each other? The role of genetics in neurological diseases is key; more than half of our genes are expressed exclusively in the brain. It is an advantage in being able to put on my neurologist’s hat and think about a patient from that point of view, and then to switch to my clinical geneticist hat when it comes to considering whether and what type of genetic evaluation is indicated. Thanks to the Human Genome Project [the project that identified and mapped the human genome, or DNA] and the ability to do whole genome analysis, clinical genetics is moving rapidly into the era of genomic medicine.
You are a specialist in the genetics of autism. Will we be able to one day identify a child’s genetic risk for this condition? We already know that the current risk for a child to have autism is 1 in 66, or 1.5 percent, according to the Centers for Disease Control and Prevention. We also know that some children are born with a higher than average risk to develop autism either because of a strong family history, or from a wide variety of known genetic conditions that increase the risk of autism. Autism is fundamentally a clinical diagnosis, not a genetic one. In about 5 to 20 percent of individuals with a diagnosis of autism, however, we can currently identify a specific genetic cause with our clinical tests. Accurately predicting the precise risk using genetic testing for a particular child to develop autism before it happens is much more complicated, and much less reliable. Identifying children at higher risk, though, either through genetic evaluation or through early diagnosis, affords the opportunity for early intervention.
It can take a long time for medical research to produce results. What motivates you? Meeting patients and their families who are living with chronic genetic diseases is a big motivation to try to find answers to simple questions: What caused my (or my child’s) disease? Is there a treatment or cure? What is going to happen? Are other people in my family going to come down with the same disease? Accurate diagnosis is the foundation that informs prognosis, treatment and risk to family members. I think that once a disease is “cured,” like polio, or smallpox, or even converted from a fatal to a chronic, manageable disease (like type 1 diabetes or HIV), it is easy to forget how deadly that disease used to be, and how much medical research has accomplished.
What was your most surprising finding? I saw a boy who was born healthy and was normal and active for the first several years, but he slowly began to have stiffness, with his feet turning in, and the family noticed he had difficulty with running and movement. The family had seen a neurologist, who referred him to me. I took a careful history and did a thorough neurological exam. I recognized a rare, neurogenetic condition in him called dopa-responsive dystonia, or Segawa disease. I prescribed a medication to treat the condition, and weeks later, his mother wrote me an email saying that he had responded remarkably well. He was essentially back to being a normal boy again. —MANDOLIN BRASSAW