Why diagnosis isn’t the answer when it comes to the rarest of diseases

“Mr. and Mrs. Smith, we finally have an answer for you.” The couple, whose real names we are protecting for privacy, looked at me anxiously. I had been evaluating their young daughter, Sally, in my role as a medical geneticist at the Children’s Hospital at Montefiore in the Bronx, a borough of New York City. For years, the Smiths had been searching to learn why Sally was suffering from epilepsy, why she didn’t seem to understand them and why she wasn’t speaking at 6 years of age. In 2021, they ended up in my clinic.

I decided to send a sample of Sally’s blood for whole-exome sequencing, a test that could identify a change in one of her genes that might be responsible for her symptoms. A few weeks later I had the answer.

“Sally has an extremely rare disorder that you’ve probably never heard of,” I told them. “It’s so rare that it doesn’t even have a real name yet. It’s called NAA10-related disorder.” The family looked at me with blank stares. I took a deep breath and continued.