High Resolution Melting Analysis (HRMA) for the identification of a rare UGT1A1 promoter polymorphism

High-resolution melting analyses for genetic variants in ARID5B and IKZF1 with childhood acute lymphoblastic leukemia susceptibility loci in Taiwan

BACKGROUND

Childhood acute lymphoblastic leukemia (ALL), a heterogeneous disease that includes multiple subtypes is defined by cell lineage and chromosome anomalies. Previous genome-wide association studies have reported several ARID5B and IKZF1 single nucleotide polymorphisms (SNPs) associated with the incidence of ALL. High-resolution melting (HRM) analysis is a rapid and convenient technique to detect SNPs; we thereby detected SNPs in ARID5B and IKZF1 genes.

METHODS

We enrolled 79 pediatric ALL patients and 80 healthy controls. Polymorphic variants of IKZF1 (rs6964823, rs4132601, and rs6944602) and ARID5B (rs7073837, rs10740055, and rs7089424) were detected by HRM, and SNPs were analyzed for association with childhood ALL.

RESULTS

The distribution of genotype rs7073837 in ARID5B significantly differed between ALL and controls (P=0.046), while those of IKZF1 (rs6964823, rs4132601, and rs6944602) and ARID5B (rs10740055 and rs7089424) did not. We analyzed the association for SNPs with B lineage ALL to find rs7073837 in ARID5B, conferring a higher risk for B lineage ALL (odds ratio, OR=1.70, 95% confidence interval, CI=1.01-2.87, P=0.049).

CONCLUSION

HRM is a practical method to detect SNPs in ARID5B and IKZF1 genes. We found that rs7073837 in ARID5B correlated with a risk for childhood B lineage ALL.

UGT1A1 (TA)n genotyping in sickle-cell disease: high resolution melting (HRM) curve analysis or direct sequencing, what is the best way?

BACKGROUND

Minucci et al. have proposed in 2010 a rapid, simple and cost-effective HRM method on the LightCycler 480® apparatus (Roche) for the determination of the 6/6, 6/7 and 7/7 genotypes of the (TA)n UGT1A1 promoter polymorphism. However, they have not studied the n=5 and n=8 alleles which can be quite frequent in sickle-cell disease patients.

METHODS

The aim of our study was to test this HRM protocol to all the 10 possible (TA)n UGT1A1 genotypes (i.e. 5/5, 5/6, 5/7, 5/8, 6/6, 6/7, 6/8, 7/7, 7/8 and 8/8) by using our SCD cohort of patients.

RESULTS

All genotypes could be unambiguously identified except 6/7 and 6/8 which give a similar HRM profile. For those two genotypes, the differentiation necessitates either a direct Sanger sequencing or a second PCR protocol followed by a 3% agarose gel migration.

CONCLUSIONS

For the (TA)n UGT1A1 promoter genotyping of African patients, each lab has to wonder what is the best way between (i) direct Sanger sequencing of all patients and (ii) HRM protocol for all patients followed by a complementary analysis to differentiate the 6/7 and 6/8 genotypes.