An SSP-PCR method for the rapid detection of disease-associated alleles HLA-A*29 and HLA-B*51.

HLA-A*29 and HLA-B*51 are associated with birdshot uveitis and Behçet's disease, respectively, and are used as a diagnostic criterion in patients with suspected disease, requiring their detection in diagnostic laboratories. While commercial tests for individual HLA alleles are available for other disease-associated HLA variants, no similar allele-specific assays are available for HLA-A*29 and HLA-B*51. Here, we report sequence-specific priming-polymerase chain reaction (SSP-PCR) methods for the detection of HLA-A*29 and HLA-B*51 using a single PCR reaction per allele. The assays were tested in 30 and 32 previously HLA-typed samples, respectively, representing >97% of HLA-A alleles and >93% of HLA-B alleles in a European population. A concordance of 100% was observed with previous typing results, validating these methods for use in a diagnostic or research context.

Novel Genetic Variants in Carboxylesterase 1 Predict Severe Early-Onset Capecitabine-Related Toxicity.

An important concern with the anticancer drug capecitabine (Cp), an oral prodrug of 5-fluorouracil, are dose-limiting adverse effects, in particular hand-foot syndrome (HFS) and diarrhea. Here we evaluated the association of genetic variability in all enzymes of the Cp-activation pathway to 5-fluorouracil with Cp-related early-onset toxicity in 144 patients receiving Cp. We identified a haplotype encompassing five variants in the carboxylesterase 1 (CES1) gene region including an expression quantitative trait locus associated with early-onset Cp-toxicity (Haplotype A3: ORadditive = 2.2, 95% CI 1.2-4.0, Padjusted = 0.012; ORrecessive = 10.3, 95% CI 2.1-49.4, Padjusted = 0.0038). Furthermore, the association of two linked cytidine deaminase (CDA) promoter variants (c.1-451C>T: ORdominant = 4.3, 95% CI 1.3-14.2, Padjusted = 0.017; and c.1-92A>G: ORdominant = 4.4, 95% CI 1.3-14.5, Padjusted = 0.015) with Cp-related diarrhea was replicated. This first study identifying an association of genetic variation in CES1 with Cp-related toxicity provides further evidence for the existence of a functional noncoding CES1-variant with a possible regulatory impact.

The impact of ABCC11 polymorphisms on the risk of early-onset fluoropyrimidine toxicity.

A missense variant (c.1637C>T, T546M) in ABCC11 encoding the MRP8 (multidrug resistance protein 8), a transporter of 5-fluorodeoxyuridine monophosphate, has been associated with an increased risk of 5-fluorouracil-related severe leukopenia. To validate this association, we investigated the impact of the ABCC11 variants c.1637C>T, c.538G>A and c.395+1087C>T on the risk of early-onset fluoropyrimidine-related toxicity in 514 cancer patients. The ABCC11 variant c.1637C>T was strongly associated with severe leukopenia in patients carrying risk variants in DPYD, encoding the key fluoropyrimidine-metabolizing enzyme dihydropyrimidine dehydrogenase (odds ratio (OR): 71.0; 95% confidence interval (CI): 2.5-2004.8; Pc.1637C>T*DPYD=0.013). In contrast, in patients without DPYD risk variants, no association with leukopenia (OR: 0.95; 95% CI: 0.34-2.6) or overall fluoropyrimidine-related toxicity (OR: 1.02; 95% CI: 0.5-2.1) was observed. Our study thus suggests that c.1637C>T affects fluoropyrimidine toxicity to leukocytes particularly in patients with high drug exposure, for example, because of reduced fluoropyrimidine catabolism.

HLA-A 31:01 and HLA-B 15:02 as genetic markers for carbamazepine hypersensitivity in children.

The occurrence of hypersensitivity reactions including rare but life-threatening Stevens-Johnson syndrome (SJS) and drug-induced hypersensitivity syndrome (HSS) limits the use of the anticonvulsant carbamazepine (CBZ). Human leukocyte antigen-B (HLA)-B 15:02 and HLA-A 31:01 have been identified as predictive genetic markers for CBZ hypersensitivity in Asian and European patients. To replicate these genetic associations in pediatric patients from North America with a diverse ethnic background, we investigated HLA-A 31:01 and HLA-B 15:02 in 42 children with CBZ hypersensitivity and 91 CBZ-tolerant children from across Canada. HLA-A 31:01 was significantly associated with CBZ-HSS (odds ratio (OR): 26.4, P = 0.0025) and maculopapular exanthema (MPE) (OR: 8.6, P = 0.0037) but not with CBZ-SJS. Conversely, HLA-B 15:02 was associated with CBZ-SJS (OR: 38.6, P = 0.002) but not HSS or MPE. This study is the first to demonstrate the association of HLA-A 31:01 with CBZ hypersensitivity in children, providing important replication of this association and highlighting the importance of HLA-A 31:01 as a predictive biomarker across various ancestries.