Figure 4

Proportion of patients with an unremarkable neurocognitive outcome in symptomatic isovaleric acidemia. The percentage of patients with normal cognitive abilities (intelligence quotient [IQ] scores) including academic performance (absence of learning disabilities) is presented for the group of study patients (n = 20). In the group of patients reported in the literature (n = 108), neurocognitive outcome was defined as normal if reported as "normal" or "excellent" and/or normal IQ scores were available. Patients were subdivided into an early diagnosis group (defined as a diagnosis made within the first 5 weeks of life) and a late diagnosis group (defined as a diagnosis made thereafter). Of 20 study patients, 11 were diagnosed early and nine were diagnosed late (median 3.7 years; range 1.6-6.5 years). Of 108 patients in whom information on neurocognitive outcome was available in the literature, 46 were diagnosed early and 62 were diagnosed late.