Validation of a "new" short tandem repeat (STR) fluorescent multiplex system and report of population genetic data.

The Humantype Chimera PCR Amplification Kit contains 12 polymorphic loci (ACTBP2 (= SE33), D18S51, D4S2366, D6S474, D8S1132, D12S391, D2S1360, D3S1744, D5S2500, D7S1517, D10S2325, D21S2055), of which the latter 10 loci have not been used extensively for human identity testing. The sex determinant locus amelogenin is also included in the kit. Amplification was successful on a variety of thermal cyclers and the amplicons could be analyzed on both the ABI PRISM 310 and 3100 Genetic Analyzers. Complete genotyping results from single source samples were possible between 0.25 and 2 ng of DNA template. Heterozygote imbalance (< 60% peak height balance) caused by stochastic effects was observed at a rate of around 5%. No deviations from the Hardy-Weinberg equilibrium were observed. Thus, there were no detectable significant deviations from the expected genetic independence of alleles.

Surprising negative association between IgG1 allotype disparity and anti-adalimumab formation: a cohort study.

INTRODUCTION: The human monoclonal antibody adalimumab is known to induce an anti-globulin response in some adalimumab-treated patients. Antibodies against adalimumab (AAA) are associated with non-response to treatment. Immunoglobulins, such as adalimumab, carry allotypes which represent slight differences in the amino acid sequences of the constant chains of an IgG molecule. Immunoglobulins with particular IgG (Gm) allotypes are racially distributed and could be immunogenic for individuals who do not express these allotypes. Therefore, we investigated whether a mismatch in IgG allotypes between adalimumab and IgG in adalimumab-treated patients is associated with the development of AAA. METHODS: This cohort study consisted of 250 adalimumab-treated rheumatoid arthritis (RA) patients. IgG allotypes were determined for adalimumab and for all patients. Anti-idiotype antibodies against adalimumab were measured with a regular radio immunoassay (RIA), and a newly developed bridging enzyme linked immunosorbent assay (ELISA) was used to measure anti-allotype antibodies against adalimumab. The association between AAA and the G1m3 and the G1m17 allotypes was determined. For differences between groups we used the independent or paired samples t-test, Mann-Whitney test or Chi square/Fisher's exact test as appropriate. To investigate the influence of confounders on the presence or absence of AAA a multiple logistic regression-analysis was used. RESULTS: Adalimumab carries the G1m17 allotype. No anti-allotype antibodies against adalimumab were detected. Thirty-nine out of 249 patients had anti-idiotype antibodies against adalimumab (16%). IgG allotypes of RA patients were associated with the frequency of AAA: patients homozygous for G1m17 had the highest frequency of AAA (41%), patients homozygous for G1m3 the lowest frequency (10%), and heterozygous patients' AAA frequency was 14% (P = 0.0001). CONCLUSIONS: An allotype mismatch between adalimumab and IgG in adalimumab-treated patients did not lead to a higher frequency of AAA. On the contrary, patients who carried the same IgG allotype as present on the adalimumab IgG molecule, had the highest frequency of anti-adalimumab antibodies compared to patients whose IgG allotype differed from adalimumab. This suggests that the allotype of adalimumab may not be highly immunogenic. Furthermore, patients carrying the G1m17-allotype might be more prone to antibody responses.