Scandinavian Journal of Rheumatology 03/2015; 44(3):1-2. DOI:10.3109/03009742.2015.1005663 · 2.53 Impact Factor
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To establish gene copy number (GCN)-specific normal ranges for serum C4 genes and to determine their utility with respect to the interpretation of chronically low serum C4 concentrations in patients with clinically quiescent systemic lupus erythematosus (SLE).MethodsC4 serum concentrations were estimated by automated turbidimetry, and C4 GCNs were determined using the TaqMan real-time polymerase chain reaction (PCR) analysis in 184 unselected individuals and in 10 patients with type 1 diabetes mellitus (DM) who were selected for the presence of only 2 copies of the C4 gene. C4 GCNs were also determined in 11 patients with clinically quiescent SLE who had chronically low serum C4 concentrations.ResultsA total of 33% of the variation in serum C4 concentrations could be accounted for by both C4A and C4B GCNs (R2 = 0.30, P ≤ 0.0001). There was a median of 2 gene copies at the C4A locus (53.8%) and 2 at the C4B locus (58.7%). The median total number of C4 genes was 4 (55.4%). C4 GCN-specific normal ranges were established. A chronically low serum C4 concentration was explained by a low C4 GCN in 3 of 11 patients tested.Conclusion
This study establishes the feasibility of establishing C4 GCN-specific normal ranges using the TaqMan real-time PCR assay. Chronically low serum C4 concentrations in SLE patients are sometimes explained by low C4 GCNs.
Arthritis and Rheumatology 09/2014; 66(9). DOI:10.1002/art.38680
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ABSTRACT: BACKGROUND Diagnosis of latent tuberculosis infection (LTBI) is a cornerstone of the health assessment of resettled high incidence populations, particularly in children. Two blood-based interferon gamma release assays (IGRAs), T-SPOT.TB and QFT-Gold in-tube (QFT-GIT), have greater sensitivity and specificity than the tuberculin skin test (TST), but their performance as screening tools for LTBI in children, especially refugee children, remains unclear. METHODS 524 African and ethnic Burmese children, including 107 under 3 years of age, were prospectively enrolled in a comparison of the T-SPOT.TB and QFT-GIT. The TST was also performed in 342 of the children. RESULTS The T-SPOT.TB and QFT-GIT had similar rates of positivity (8% and 10%, respectively) and showed good concordance when both tests gave definitive results (kappa=0.78; p<0.0001). However, the IGRAs had significant failure rates: 15% of QFT-GIT gave indeterminate results due to failed mitogen response and 14% of T-SPOT.TB results were inconclusive, largely because of insufficient mononuclear leucocyte yields. Failure of the QFT-GIT mitogen response was associated with African ethnicity and co-morbid infections, particularly with helminths. The TST results showed poor concordance ( approximately 50%) with both IGRAs. CONCLUSIONS It is reasonable to screen using either IGRA with follow-up by the alternative if the test fails. In general, the QFT-GIT is the preferred option for non-African populations but the T-SPOT.TB is recommended when there are epidemiological and/or clinical high risk factors for TB infection. However, both IGRAs have methodological and performance characteristics that limit their usefulness in refugee children, highlighting the need for continued development of screening strategies.
Thorax 05/2010; 65(5):442-8. DOI:10.1136/thx.2009.127555 · 8.29 Impact Factor
Human Immunology 10/2008; 69. DOI:10.1016/j.humimm.2008.08.146 · 2.14 Impact Factor