Additional file 1: Figure S1. Analyses for which the mean annual volumes were not modified by the feasibility study results. Comparison of the volumes of tests reported by the Belgian laboratories of clinical pathology for 6 different years: group A (light grey bars, period before the presentation of the results of the feasibility study [data collected for 2014 and 2015]) versus group B (dark grey bars, period after the presentation of the results of the feasibility study [data collected for 2016 and 2017]) versus group C (black bars, period from RLs’ recognition [data collected for 2019 and 2020]). Values were calculated as mean volumes ± SD, n = 2 for the 3 groups (A,B,C) of two successive years. Statistical analyses were performed by one-way ANOVA with Tukey’s posttest for multiple comparisons between the 3 groups. The absence of asterisks indicates values that are not statistically significantly different from each other (p ≥ 0.05). Analyses presented in each panel: a: assessment of Complement component Factor D; b: assessment of Complement component Factor P; c: assessment of plasma porphobilinogen; d: fractionation of plasma porphyrins; e: assessment of the dihydropteridine reductase activity in dried blood spots; f: assessment of plasmalogen levels in red blood cells; g: cytogenetic radiosensitivity assay; h: assessment of δ1-piperideine-6-carboxylate in plasma; i: determination of 5-methyltetrahydrofolate in cerebrospinal fluid; j: analysis of the deformability of erythrocytes using osmotic gradient ektacytometry and separation of red blood cells membrane proteins by SDS-PAGE; k: assessment of free erythrocyte protoporphyrins; l: spectrofluorimetric assessment of plasma porphyrins. Abbreviations: RLs: Reference laboratories.