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Background: There is a shortage of data on the accuracy of statistical methods for the prediction of N-acetyltransferase 2 (NAT2) haplotypes in the mixed ancestry population of the Western Cape. Objective: This study aimed to identify the NAT2 haplotypes and assess the accuracy of PHASE version 2.1.1 in assigning NAT2 haplotypes to a mixed ancestry population from the Western Cape. Methods: This study was conducted between 2013 and 2016. The NAT2 gene was amplified and sequenced from the DNA of 100 self-identified mixed ancestry participants. Haplotyping was performed by molecular and computational techniques. Agreement was assessed between the two techniques. Results: Haplotypes were assigned to 93 samples, of which 67 (72%) were ambiguous. Haplotype prediction by PHASE demonstrated 94.6% agreement (kappa 0.94, p 0.001) with those assigned using molecular techniques. Five haplotype combinations (from 10 chromosomes) were incorrectly predicted, four of which were flagged as uncertain by the PHASE software. Only one resulted in the assignment of an incorrect acetylation phenotype (intermediate to slow), although the software flagged this for further analysis. The most common haplotypes were NAT2*4 (28%) followed by NAT2*5B (27.4%), NAT2*6A (21.5%) and NAT2*12A (7.5%). Four rare single nucleotide variants (c.589CT, c.622TC, c.809TC and c.387CT) were detected. Conclusion: PHASE accurately predicted the phenotype in 92 of 93 samples (99%) from genotypic data in our mixed ancestry sample population, and is therefore a suitable alternative to molecular methods to individualise isoniazid therapy in this high burden tuberculosis setting.

Background Biomarkers assist in diagnosing neonatal sepsis but often provide results 6 to 48 h later. Bedside C-reactive protein (CRP) test may help to expedite clinical management. We assessed the performance of point of care test (POCT) CRP against routine laboratory analysis and determined the time difference in obtaining results. Methods A prospective observational study was conducted over 4 months. Neonates clinically indicated, had CRP simultaneously tested using the POCT and laboratory assays. Results Using similar decision cut-off values of 10 mg/l, POCT compared favourably to laboratory testing. The median times to POCT result was 4 min whereas laboratory results were entered at a median of 4.1 h (95th percentile 8 h) but only checked after 5.5 h (95th percentile 19.8 h). Conclusions POCT may be a quick and reliable method to determine CRP. It may rationalize antibiotic usage, allow for earlier patient discharge and reduce overall patient management cost.

Background: Immunoassays are prone to interference by various substances which may cause inaccurate results. This type of interference is difficult to detect analytically. Objective: A case of CARDIAC Troponin T Quantitative reader (Roche Diagnostics) assayfailure was detected and investigated in order to ascertain the likely cause. Method: Patient whole blood was mixed with cardiac troponin T-positive blood, patient and control sera were denuded of immunoglobulin G by protein A-affinity chromatographyand patient sera were mixed with mouse serum. Samples were analysed on a CARDIAC Troponin T Quantitative reader. Results: A mixture of patient whole blood and cardiac troponin T-positive blood resultedin assay failure; removal of immunoglobulin G from patient sera reversed the cardiactroponin T assay failure; the addition of mouse serum as a heterophile antibody blocking agent had no effect. Conclusion: It is proposed that the interference resulting in assay failure may not be because of a heterophile antibody, but rather a result of a circulating autoantibody to cardiactroponin T, which may compete with antibody assay reagents for binding sites.