Background: Organic acidurias (OADs) and urea cycle disorders (UCDs) are inborn metabolic disorders with a risk for acute and chronic metabolic decompensation resulting in impairments of the central nervous system and other organ systems. So far, there is no systematic study of intellectual functioning, behavioural/emotional problems and health-related quality of life (HRQoL), and how these domains are connected.
Methods: Data of 152 patients with OADs (n = 100) and UCDs (n = 52) from the European Registry and Network of intoxication type Metabolic Diseases (E-IMD) using standardized instruments were compared with normative data.
Results: Behavioural/emotional problems are increased in OADs or UCDs patients by a factor of 2.5 (3.0), in female asymptomatic carriers of X-linked inherited UCD ornithine transcarbamylase deficiency (fasOTCD) by a factor of 1.5. All groups show similar patterns of behavioural/emotional problems, not different from epidemiological data. Mental disability (IQ ≤ 70) was found in 31% of OAD, 43% of UCD, but not in fasOTCD subjects. HRQoL was decreased in the physical domain, but in the normal range. Behavioural/emotional problems were significantly associated with intellectual functioning (OR = 6.24, 95%CI: 1.39-27.99), but HRQoL was independent from both variables.
Conclusions: Patients with OADs and UCDs show increased frequencies of mental disability and behavioural/emotional problems. Profiles of behavioural/emotional problems were similar to epidemiological data. Intellectual disability and behavioural/emotional problems were strongly associated. Patients' HRQoL was in the normal range, possibly compensated by coping strategies of their families. Diagnostics and clinical care of OAD/UCD patients should be improved regarding behavioural/emotional, intellectual and quality of life aspects.