Researchers at University of California, Los Angeles have worked with a California family stricken by an extremely rare, devastating disorder that attacks the brain and spine to pinpoint the cause of the disease. The researchers used a new technique called exome sequencing, which searches only the protein-coding regions in the genome to identify disease-causing mutations. They ultimately found that a defect on a gene called exosome component 3 (EXOSC3) causes the condition, pontocerebellar hypoplasia type 1 (PCH1). PCH1 symptoms manifest at or soon after birth and include poor muscle tone and growth retardation. To confirm the finding, the research team verified the presence of the defect in eight other families around the world stricken with PCH1. Furthermore, researchers found that, in zebrafish model, injecting normal EXOSC3 largely reversed symptoms, indicating a potential target for treatment.