Rapid and reliable genotyping of HLA-B*58:01 in four Chinese populations using a single-tube duplex real-time PCR assay

Prevalence of HLA-B*58:01 allele among Malay, Chinese and Indian ethnic patients with gout attending primary care clinics in Malaysia

HLA-B*58:01 allele is associated with allopurinol-induced severe cutaneous reaction (SCAR). Malaysia has a multiethnic population with limited data on the prevalence of HLA-B*58:01 among patients with gout treated in primary care settings. This cross-sectional study aimed to determine the prevalence of HLA-B*5801 in patients with gout from the Malay, Chinese and Indian ethnicities attending primary clinics in Malaysia.We collected blood samples from patients with gout attending three primary care clinics in Klang Valley, Malaysia, using convenience sampling. Genomic DNA samples were subjected to typing of HLA-B*5801 by a multiplex probe-based assay in a real-time PCR system, validated by PCR-resequencing approach.547 patients (194 Malay, 266 Chinese and 87 Indian) were recruited. The overall prevalence of HLA-B*58:01 was 16.8% (Chinese 21.8%, Indian 12.6% and Malay 11.9%). None of our 61 HLA-B*58:01 carriers who ever used allopurinol developed SCAR.The overall prevalence of HLA-B*58:01 allele in our patients with gout was high, particularly among the Chinese ethnicity (21.8%). None of our HLA-B*58:01 positive patients treated with allopurinol reported allopurinol-induced SCAR. A more accurate predictive model for allopurinol-induced SCAR is needed.

Dual approaches in pharmacogenetics: Developing PCR-SSP and RT-PCR methods for HLA-B*13:01 screening to prevent dapsone and Co-trimoxazole SCARs

Dapsone and co-trimoxazole are potent antibiotics for treating various infections and inflammations. However, several studies reported the strongly association between severe cutaneous adverse drug reactions (SCARs) to both drugs and the HLA-B*13:01 allele. Rapid and reliable screening for the HLA-B*13:01 allele can mitigate the risk of dapsone-induced SCARs. We developed two methods, multiplex sequence-specific primer PCR (PCR-SSP) and real-time PCR (RT-PCR), tailored for different clinical settings. These methods were optimized to minimize false positives among the Thai population. Clinical validation demonstrated excellent reproducibility, with both methods showing 100 % concordance in repeated tests. PCR-SSP achieved a limit of detection as low as 100 pg of genomic DNA, while RT-PCR reached 1 pg. Overall statistical accuracy was 100.00 % (95 % CI: 98.18 %-100.00 %). Screening for drug-related HLA alleles is crucial for reducing mortality from severe cutaneous adverse drug reactions, especially dapsone hypersensitivity syndrome (DHS) and dapsone-induced hypersensitivity reactions (DIHRs). Our screening approach for dapsone can also be extended to co-trimoxazole, representing a significant advancement in personalized medicine and preemptive pharmacogenetic testing for tailored patient care and safety, albeit further validation in diverse ethnic populations is warranted to ensure universal applicability.

rs144012689 is a highly specific representative marker of HLA-B*15:02 in the Chinese population

Objective: To develop an accurate and rapid real-time PCR technique for HLA-B*15:02 genotyping and investigate HLA-B*15:02 allele frequency in four ethnic populations in China. Materials & methods: Based on the highly specific representative markers, a real-time PCR assay was developed for HLA-B*15:02 genotyping, and HLA-B*15:02 allele frequencies were screened in four ethnic populations of China. Sequence-based typing was used to validate the accuracy of the assay. Results: The sensitivity and specificity of the assay were 100%, and the detection limit was 0.2 ng. The frequency of HLA-B*15:02 alleles distributed in the Bouyei population was significantly higher than in the Han group (p < 0.01). Neither the Tibetan nor the Uyghur population carried the HLA-B*15:02 haplotype. Conclusion: The authors developed an accurate HLA-B*15:02 genotyping method for evaluating the risk of adverse drug reactions induced by carbamazepine in various ethnic populations in China.

Development of a rapid and reliable single-tube multiplex real-time PCR method for HLA-A*24:02 genotyping

Aim: HLA-A*24:02 is significantly associated with cutaneous adverse drug reactions caused by aromatic antiepileptic drugs. Here, we aimed to establish a fast and reliable detection method for HLA-A*24:02 genotyping. Methods: A single-tube multiplex quantitative real-time polymerase chain reaction (qPCR) assay for HLA-A*24:02 genotyping was established by combining allele-specific primers with TaqMan probes. Results: A 100% concordance was observed between qPCR and SBT result in 106 Han subjects. The detection limit of the new method was 0.05 ng DNA. The positive rate of HLA-A*24:02 in Tibetans (55.6%, n = 81) was significantly higher than those in Han (34%, n = 106), Uighur (27.5%, n = 102), Bouyei (25.9%, n = 116) and Miao populations (26.5%, n = 113). Conclusion: The newly established qPCR assay was reliable for HLA-A*24:02 screening in clinical applications.

Developing pharmacogenetic screening methods for an emergent country: Vietnam

BACKGROUND

The finding of strong associations between certain human leukocyte antigen (HLA) genotypes and the development of severe cutaneous adverse drug reactions (SCARs), [for example, HLA-B*57:01 and abacavir (ABC), HLA-B*15:02 and carbamazepine (CBZ) and HLA-B*58:01 and allopurinol], has led to HLA screening being used to prevent SCARs. Screening has been shown to be of great benefit in a number of studies. Clinical translation from bench to bedside, however, depends upon the development of simple, rapid and cost-effective assays to detect these risk alleles. In highly populated developing countries such as Vietnam, where there is a high prevalence of HLA-B*15:02 and HLA-B*58:01 correlating with a high incidence of CBZ- and allopurinol-induced SCARs, the crucial factor in the implementation of comprehensive screening programs to detect these major risk HLA alleles is the availability of suitable assays.

BODY

We have summarized the role and economic benefits of HLA screening, reviewed published HLA screening methods used currently in pharmacogenetic screening and examined the advantages and disadvantages of assays developed specifically for use in screening for risk alleles in the prevention of HLA-associated SCARs in Vietnam.

CONCLUSION

The optimal approach we propose may serve as a template for the development of screening programs in other emergent countries.

Clinical evaluation of a substitute of HLA-B*58:01 in different Chinese ethnic groups

The goal of this research was to investigate the linkage disequilibrium between rs9263726 and HLA-B*58:01 in different Chinese ethnic groups (Han, Tibet, and Hui) and to study the feasibility of rs9263726 replacing HLA-B*58:01 as an efficient indicator of potential allopurinol hypersensitivity syndrome. In this study, rs9263726 and HLA-B*58:01 were detected in all samples. For samples of individuals whose rs9263726 genotypes were not consistent with HLA-B*58:01, we did high-resolution typing of HLA-B gene to further confirm the correlation of rs9263726 genotype and special HLA-B alleles. We confirmed that the linkage disequilibrium between rs9263726 and HLA-B*58:01 was more significant in the Han ethnic group (r2=0.886, D'=1.0) than in the Tibet and Hui ethnic groups (for Tibetan, r2=0.606, D'=0.866; for Hui, r2=0.622, D'=0.924). For Han Chinese, samples with the GG genotype of rs9263726 did not carry HLA-B*58:01, while AA genotype samples were homozygous carriers of HLA-B*58:01. However, GA genotype samples of rs9263726 required a more sophisticated HLA-B genotyping assay before it was possible to identify whether they were HLA-B*58:01 carriers or not. For Tibetan and Hui, the linkage disequilibrium between rs9263726 and HLA-B*58:01 was not significant. Therefore, rs9263726 cannot replace HLA-B*58:01 in these two groups.

Single-tube multiplex real-time PCR assay for rapid and reliable detection of HLA-A*31:01 allele

AIM

HLA-A*31:01 has been associated with carbamazepine-induced hypersensitivity reactions. HLA-A*31:01 genetic testing is recommended before the initiation of carbamazepine therapy.

METHODS

A novel real-time PCR assay was designed for HLA-A*31:01 detection by allele-specific primers and TaqMan minor groove binding probes.

RESULTS

The genotyping results in 100 subjects by the established method who were in 100% agreement with the sequencing-based typing method. The assay presents a sensitivity of 1 (95% CI: 0.69-1.00), a specificity of 1 (95% CI: 0.96-1.00) and a positive and negative predictive value of 1. The carrier rates of HLA-A*31:01 in Tibetan (n = 45), Han Chinese (n = 100), Miaos (n = 48) and Khalkhas (n = 48) were 22.2, 10, 4.2 and 18.8%, respectively.

CONCLUSION

This assay is reliable to detect HLA-A*31:01 and would be useful to prevent carbamazepine-induced hypersensitivity reactions.

Rapid and reliable screening of HLA-B*15:02 in four Chinese populations using single-tube multiplex real-time PCR assay

AIM

 HLA-B*15:02 screening should be performed to prevent antiepileptic drug induced severe cutaneous adverse reactions in populations of Asian origin. This study aimed to develop fast and reliable HLA-B*15:02 genotyping method and to investigate the distribution of HLA-B*15:02 in different Chinese ethnicities.

MATERIALS & METHODS

A single-tube multiplex real-time PCR assay for HLA-B*15:02 genotyping was established by combining allele-specific primers with TaqMan probes.

RESULTS

The HLA-B*15:02 genotyping results in Bouyei (n = 100) by the established assay were completely consistent with the corresponding PCR sequence-based typing findings. The percentage of HLA-B*15:02 carrier in Bouyei (19%; n = 100) was significantly higher than those of Han (1%; n = 100), Tibetan (0%; n = 100) and Uyghur (0%; n = 50) populations (p < 0.001).

CONCLUSION

The novel method provides rapid, reliable and cost-effective detection of HLA-B*15:02 allele in clinical applications.

Validation of a Rapid, Robust, Inexpensive Screening Method for Detecting the HLA-B*58:01 Allele in the Prevention of Allopurinol-Induced Severe Cutaneous Adverse Reactions

The HLA B^*58:01 allele has been worldwide reported as a pharmacogenetic susceptibility to allopurinol-induced severe cutaneous adverse reactions (SCARs). To prevent these life-threatening conditions, the American College of Rheumatology hingly recommended that the HLA-B^*58:01 be screened prior to the initiation of allopurinol therapy. Therefore, we developed a rapid, robust, inexpensive screening method using SYBR® Green real time PCR to detect the HLA-B^*58:01 allele. A total of 119 samples were tested. The assay has a sensitivity of 100% (95% CI: 69.15%-100%), a specificity of 100% (95% CI: 96.67%-100%), a positive predictive value of 100% (95% CI: 69.15%-100%) and a negative predictive value of 100% (95% CI: 96.67%-100%). HLA-B^*58:01 genotyping results showed 100% agreement with those obtained from Luminex SSO/SBT/SSP. The lowest limit of detection of this method is 0.8 ng/µL of DNA. The unit cost of the test is only $3.8 USD. This novel screening test using SYBR® real time PCR would be appropriate to identify individuals with the HLA-B^*58:01 allele for the prevention of allopurinol-induced SCARs.