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BACKGROUND Genotyping for clinically important single nucleotide polymorphisms (SNPs) is performed by many clinical routine laboratories. To support testing, quality controls and reference materials are needed. Those may be derived from residual patient samples, left over samples of external quality assurance schemes, plasmid DNA or DNA from cell lines. DNAs from cell lines are commutable and available in large amounts. METHODS DNA from 38 cell lines were examined for suitability as controls in 11 SNP assays that are frequently used in a clinical routine laboratory: FV (1691G>A), FII (20210G>A), PAI-1 4G/5G polymorphism, MTHFR (677C>T, 1298A>C), HFE (H63D, S65C, C282Y), APOE (E2, E3, E4), LPH (-13910C>T), UGT1A1 (*28, *36, *37), TPMT (*2, *3A, *3B, *3C), VKORC1 (-1639G>A, 1173C>T), CYP2C9 (*2, *3, *5). Genotyping was performed by real-time PCR with melting curve analysis and confirmed by bi-directional sequencing. RESULTS We find an almost complete spectrum of genotypic constellations within these 38 cell lines. About 12 cell lines appear sufficient as genotypic controls for the 11 SNP assays by covering almost all of the genotypes. However, hetero- and homozygous genotypes for FII and the alleles TPMT*2, UGT1A1*37 and CYP2C9*5 were not detected in any of the cell lines. CONCLUSIONS DNA from most of the examined cell lines appear suitable as quality controls for these SNP assays in the laboratory routine, as to the implementation of those assays or to prepare samples for quality assurance schemes. Our study may serve as a pilot to further characterize these cell lines to arrive at the status of reference materials.

No full international consensus exists on disease markers to be used for assessing the human iron status. Therefore this study was conducted to compare performances of serum ferritin and transferrin saturation (TSAT) versus soluble transferrin receptor (sTfR)/log ferritin and reticulocyte hemoglobin content (CHr), also known as Thomas-plot, in the diagnosis of iron deficiency (ID).A total of 445 consecutive hospitalized patients, referred for routine testing of the actual iron status, were included. Logistic regression models for the probability of functional ID (CHr28pg) were constructed for all 445 patients, for 225 patients without (C-reactive protein [CRP]≤0.5mg/dL) and 220 patients with acute-phase reaction (CRP0.5mg/dL).Based on the Thomas-plot analyses, 153/445 (34.38%) patients were identified with ID. When ID was diagnosed by means of serum ferritin levels30ng/mL and TSAT levels20%, 105/445 (23.60%) and 215/445 (48.31%) patients were identified with ID, respectively. The sTfR/log ferritin ratio showed the best positive predictive values (PPV) (62.50 and 64.41%) to indicate functional ID in patients without as well as with acute-phase reaction compared to sTfR (58.14 and 61.67%), ferritin (32.50 and 32.86%) and TSAT (26.74 and 42.86%).In clinical practice, the prevalence of ID and the accuracy to detect functional ID are dependent on marker selection and its definition. Regarding the results of this work, for laboratory investigation of ID, however, we suggest using Thomas-plot analyses in combination with ferritin single-marker measurements to efficiently identify patients with ID.