Haptoglobin polymorphism in Mongolian population: Comparison of the two genotyping methods

Haptoglobin polymorphisms in Latin American populations

Several genetic polymorphisms of the haptoglobin gene (HP) or haptoglobin-related gene (HPR) were reported to show a population-specific distribution and to be associated with not only serum haptoglobin (HP) but also cholesterol levels. For such association studies, it is important to know the distribution of polymorphisms or their haplotypes in the populations concerned. However, no comprehensive genetic studies have explored this in Latin Americans, and not every human variation or genotype is available in a database. In this study, we determined the genotypes of common HP (HP¹ and HP²), HP^del, rs5471, rs5472, and rs2000999 in several Latin American populations. Haplotypes of rs5472-common HP-rs2000999 polymorphisms were estimated. We did not encounter any HP^del, and the frequencies of rs5471 A, rs5472 A, HP¹, and rs2000999 G were higher than their counterpart alleles in studied populations. All of the alleles with higher frequency in the Latin Americans are associated with higher serum HP and lower cholesterol levels. Both A-1-G (probably HP^1S) and G-1-G (probably HP^1F) haplotypes were higher in Latin American populations than those in other geographic regions. In addition, the genetic influx from populations of other continents into Peruvians seems to be relatively lower than that into other Latin Americans.

Serum haptoglobin correlates positively with cholesterol and triglyceride concentrations in an obese Mongolian population

BACKGROUND

Recent studies revealed that several genetic polymorphisms of haptoglobin gene (HP) and the haptoglobin-related protein gene (HPR) associated not only with haptoglobin (HP) but total, non-HDL, and/or LDL cholesterol concentrations in various populations.

METHODS

Association between serum HP concentrations and polymorphisms of HP and the HPR gene, or anthropometric and metabolic factors were examined in Mongolian participants (n = 927) using linear regression analyses.

RESULTS

The association of HP and HPR polymorphisms with serum HP concentration but not serum lipids concentrations was observed. However, subgroup analysis revealed that the association of HP and HPR polymorphisms with serum HP concentration was weakened in subgroup of obese (BMI ≥ 30) subjects and positive correlations between serum HP and non-HDL cholesterol, HDL cholesterol or triglyceride concentrations were observed in the obese subjects as compared with in subgroups of normal weight (BMI < 25) and overweight (25 ≤ BMI < 30) subjects.

CONCLUSION

The degree of obesity strongly affects the relationships between serum HP concentrations and several genetic, anthropometric and metabolic factors. These results suggested that we need to take into account the degree of obesity when considering the HP polymorphisms as predictive markers for clinical states.

Haptoglobin levels are influenced by Hp1-Hp2 polymorphism, obesity, inflammation, and hypertension in type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is an inflammatory condition associated to obesity and increased oxidative stress. Haptoglobin (Hp) is an acute phase reactant that scavenges extracorpuscular hemoglobin from circulation and prevents heme-iron oxidative damage.

OBJECTIVE

To assess the association between Hp levels and Hp1-Hp2 gene polymorphism and clinical and laboratory parameters in patients with T2DM.

METHODS

The study sample consisted of 102 T2DM patients and 62 controls. Hp plasma levels were measured using an ELISA assay, and Hp genotyping was performed using a specific two-step allelic polymerase chain reaction.

RESULTS

Hp levels were higher in T2DM patients as compared to controls (p=0.005). T2DM patients with high blood pressure had higher Hp levels than patients without this comorbidity (p=0.021). Obese T2DM patients had higher Hp levels as compared to obese controls (p=0.009) and to non-obese T2DM patients (p=0.003). The Hp1-Hp1 genotype was showed to be associated to T2DM according to additive (OR=3.038, 95% CI 1.127-8.192; p=0.036) and dominant model (OR=0.320, 95% CI 0.118-0.839; p=0.010), but Hp2 allele carriers contributed with higher Hp levels in T2DM as compared to controls. Waist circumference (p=0.002), BMI (p=0.001), and IL-6 (p=0.012), and hs-CRP (p=0.001) levels positively correlated with Hp levels in the T2DM group.

CONCLUSION

These results suggest that Hp levels are influenced by Hp1-Hp2 polymorphism, obesity, inflammatory status, and high blood pressure in T2DM.

Differentially expressed haptoglobin as a potential biomarker for type 2 diabetic mellitus in Hispanic population

Glycosylated hemoglobin (HbA1c) measurement is currently a primary tool for diagnosis of type 2 diabetes mellitus (T2DM), especially for the assessment of chronic hyperglycemia. However, many studies reported the limitation of using HbA1c for T2DM diagnosis/prognosis, such as poor sensitivities, difficult standardization, and variable cut points across ethnic groups. Therefore, the aim of this study was to discover novel biomarkers associated with elevated HbA1c levels as complementary T2DM diagnostic tools. Two-dimensional difference gel electrophoresis combined with mass spectrometry were applied for protein profile analyses of two pooled serum samples collected from Hispanic T2DM subjects (n = 74) with HbA1c ≥7 and HbA1c< 7, respectively. Isoforms of haptoglobin (Hp) α1/α2 chains were significantly altered in pooled serum samples from T2DM subjects with HbA1c ≥7 compared to those with HbA1c< 7. Hp genotypes of 262 Hispanic subjects, including 109 T2DM and 153 nondiabetic controls, were further determined by PCRs and western blotting analysis. Meanwhile, a new droplet digital PCR method for Hp genotyping was also established. The distribution of Hp2 allele was higher in T2DM subjects compared to nondiabetic controls and the HbA1c levels of T2DM subjects carrying at least one Hp2 allele tended to be higher than T2DM subjects with Hp 1-1. In summary, our results indicate that differentially expressed serum Hp protein isoforms could be associated with HbA1c levels and subjects with Hp2 allele have a higher risk for the occurrence of T2DM in Hispanic population. © 2016 BioFactors, 43(3):424-433, 2017.

A review of haptoglobin typing methods for disease association study and preventing anaphylactic transfusion reaction

Haptoglobin, the product of the Hp gene, is a glycoprotein involved in the scavenging of free hemoglobin. Haptoglobin levels increase or decrease in response to various acquired conditions, and they are also influenced by genetic predisposition. There were 2 major alleles, Hp (1) and Hp (2), and 1 minor allele, Hp (del) . Many researchers have attempted to study the haptoglobin types and their association with disease; however, no definitive conclusions have been reached yet. It is reported that patients who are genetically deficient in haptoglobin are at risk of anaphylaxis against blood components containing haptoglobin. Haptoglobin genotypes also affect the reference intervals of haptoglobin levels. Many studies have attempted to establish simple and accurate typing methods. In this paper, we have broadly reviewed several methods for haptoglobin typing-phenotyping, Southern blotting, conventional PCR, real-time PCR, and loop-mediated isothermal amplification. We discuss their characteristics, clinical applications, and limitations. The phenotyping methods are time consuming and labor intensive and not designed to detect patients harboring Hp (del) . The rapid and robust haptoglobin genotyping may help in preventing fatal anaphylactic reactions and in establishing the relationships between the haptoglobin phenotypes and diseases.

Haptoglobin 2-2 genotype is associated with increased risk of type 2 diabetes mellitus in northern Chinese

The aim of this study was to investigate the association between haptoglobin (Hp) gene polymorphism and occurrence of type 2 diabetes mellitus (T2DM) in a northern Chinese population. We studied the association of the Hp gene polymorphism with T2DM in 584 unrelated T2DM patients and 690 control subjects with normal glucose tolerance among northern Chinese. The patients were diagnosed in accordance with the guidelines of the American Diabetes Association. The clinical characteristics of the study population were recorded, and the Hp genotype was determined. The frequencies of the genotypes in the group of T2DM patients and the controls were as follows: Hp2-2, 51.7% and 44.1%; Hp2-1, 39.7% and 45.1%; and Hp1-1, 8.6% and 10.9%, respectively. There was significant difference for the genotypic and allelic distribution between the two groups (p=0.021 and p=0.007, respectively). Even after readjusting for the confounding effects of age, gender, and body mass index, a significant effect of genotypes on T2DM was still found in the recessive model for the Hp2 allele tested (p=0.002). Those who had the Hp2-2 genotype had a significantly higher risk for T2DM than those with other genotypes (odds ratio=1.441, 95% confidence interval=1.143-1.817). The results showed that the Hp2-2 genotype is associated with increased risk of T2DM in the northern Chinese Han population.

TaqMan-based real-time polymerase chain reaction for detection of FUT2 copy number variations: identification of novel Alu-mediated deletion

BACKGROUND

The human FUT2 locus, which encodes a secretor-type α(1,2)fucosyltransferase, is known to be highly polymorphic. In addition to many single-nucleotide polymorphisms, three recombination alleles with a deletion of complete or partial FUT2 coding region have been reported.

STUDY DESIGN AND METHODS

To detect copy number variations (CNVs) of the FUT2 gene including three recombinant alleles by a high-throughput system, we developed a triplex TaqMan real-time polymerase chain reaction (PCR) method. The relative number of copies of two regions of the FUT2 gene, the 5' flanking (FUT2-5') and FUT2-promoter (Prom) regions, were determined by comparing the number of threshold cycles (Ct) to those of the albumin gene (ALB) as the internal control (ΔCt).

RESULTS

The mean 2(-ΔΔCt) values (FUT2-5'/ALB or Prom/ALB) obtained from 237 samples with known FUT2 copy numbers clearly differentiated two nonoverlapping intervals that corresponded to the one-copy-number samples ranging from 0.42 to 0.59 and two-copy-number samples ranging from 0.81 to 1.19; no FUT2-5' signal for recombination alleles was detected in homozygotes. Using this assay, we detected an individual in a Chinese population with a loss of one copy of the FUT2-5' region resulting from a novel Alu-mediated FUT2 deletion (approx. 4 kb).

CONCLUSIONS

The TaqMan real-time PCR method was able to detect the number of copies of FUT2 and distinguish different kinds of known CNVs. This system is robust, fast, and suitable for high-throughput analysis.