Spectrum of Organic Aciduria Diseases in Tunisia: A 35-year Retrospective Study

Abstract

Background: Organic aciduria diseases (OADs) occur worldwide, with differences in prevalence and patterns between populations. Objectives: To describe the spectrum of OADs identified in Tunisia over a 35-years period. Materials and Methods: This retrospective study included patients who were diagnosed with OADs between 1987 and 2022 in the Laboratory of Biochemistry, Rabta Hospital, Tunisia. Organic acids were analyzed using gas chromatography–mass spectrometry. Results: A total of 30,670 urine samples were analyzed for OADs, of which 471 were positive for OADs. The estimated incidence of OADs in Tunisia was 6.78 per 100,000 live births. Methylmalonic (n = 146) and propionic (n = 90) acidurias were the most common OADs (estimated incidence: 2.10 and 1.30 per 100,000 live births, respectively). There were 54 cases of L-2-hydroxyglutatric acidurias and 30 cases of pyroglutamic acidurias, which makes it one of the highest in the world. The main clinical features were hypotonia (65%) and feeding difficulties (41%). Age at diagnosis was highly variable, ranging from 1 day to 49 years. Only 27% of the patients were diagnosed within the first month of life. The prevalence of OADs was highest in the Center-East and Southeast regions. Conclusions: In Tunisia, OADs are relatively frequent, but there are shortcomings regarding the diagnosis of these disorders. The frequency and health/social impact of these disorders warrant the need for implementing newborn screening programs and suitable patient management.

Keywords

• incidence; inborn errors metabolism; inherited errors of amino acid metabolism; epidemiology; diagnosis; organic acidurias; tunisia