Abstract

Human genetics has uncovered a vast trove of medically relevant changes in our genomes—variants and mutations that are both far more common and difficult to interpret than experts anticipated. What will this mean as we move into an era of genomic or “precision” medicine? For over a century the overriding goal of human genetics was to explain the inheritance of traits and conditions that hailed from disciplines like medicine, psychology, and criminology. Yet today, genomics research is calling prevailing categories of human illness and difference into question. Genetic mutations are increasingly used to reclassify disease, disability, and developmental difference—a process I call genomic designation. In recent decades, this has led to the formation of support groups, foundations, specialist clinics, and dedicated literatures for genomically designated conditions like the XXX, NGLY1, Fragile X, and 1p36 Deletion Syndromes. Drawing heavily on the case of 22q11.2 Deletion Syndrome, this paper explains how a genetic test result can radically alter the way a patient is understood and treated. Finding a 22q11.2 microdeletion can lead patients, parents, and caregivers to recast other diagnoses as mere symptoms of an underlying genetic disorder. A 22q11.2DS diagnosis can also redirect medical judgment and practice towards evaluations and even interventions that were not clinically indicated. Finally, a genomically designated diagnosis like 22q11.2DS can realign the very boundary between the normal and the pathological, leading experts and caregivers to reframe clinically nonsignificant findings like an IQ of eighty-seven as the symptom of a genetic disorder. In this way, the growing avalanche of positive genetic test results is disrupting classification and practice in a wide range of disciplines, bringing new populations under the gaze of medical genetics in the process. I conclude by discussing a few salient implications for bioethics and the social studies of science and medicine.