Hb Kirikiriroa [α57(E6)Gly→Cys; HBA1: c.172G>T]: A Novel Unstable α-Globin Variant with Oxidized Derivatives Interfering with Hb A1c.

We report the identification of a novel hemoglobin (Hb) variant [α57(E6)Gly→Cys; HBA1: c.172G>T], to be referred to as Hb Kirikiriroa. The variant was detected in five subjects from two families, with familial relationship established between the families following diagnosis. A persistently elevated Hb A1c over a 1-year period prompted hemoglobinopathy screening in an adolescent male of New Zealand (NZ) European descent (case 1). Capillary electrophoresis (CE) revealed the variant was negatively charged and susceptible to oxidation, with multiple abnormal peaks detected (0.4-5.1% total Hb). Hb A1c analysis by cation exchange high performance liquid chromatography (HPLC) was the first indication of the variant in a pregnant female of NZ European descent (case 2). Cases 1 and 2 had normal complete blood counts. Isopropanol stability testing provided evidence the variant was unstable. We herein describe the characterization of Hb Kirikiriroa and clinical significance of the variant for interference with Hb A1c analysis by CE and cation exchange HPLC.

Impact of diabetes mellitus on outcome after transcatheter aortic valve replacement: Identifying high-risk diabetic population from the OCEAN-TAVI registry.

OBJECTIVES: To identify the vulnerable diabetic cohort in patients undergoing transcatheter aortic valve replacement (TAVR). BACKGROUNDS: Considerable controversy remains about whether specific cohort exists in which presence of diabetes mellitus (DM) carries adverse risk of mortality after TAVR. METHODS: Of the 2588 patients who were enrolled in the OCEAN-TAVI registry, 2526 patients with glycohemoglobin data were analyzed. The individuals were divided into DM and non-DM groups according to previous medical history of DM or using diabetic medicine, and increased HbA1c values (≥6.5%) at baseline. The primary endpoint of this study was 2-year all-cause mortality after TAVR. RESULTS: The follow up rate of clinical outcome at 1-year was 2514/2526 (99.5%) and median follow-up period was 22.5 months. DM group had 699 (27.7%) patients, in which 153 (21.9%) was diagnosed by increased HbA1c levels without previous medical history of DM. Kaplan-Meier curve of 2-year all-cause mortality presented significant difference between patients with and without DM (p = 0.029). In addition, patients with low-density lipoprotein cholesterol (LDL-C) levels > 100 mg/dl and left ventricular ejection fraction (LVEF) < 40% had great risk of mortality after TAVR (LDL-C: hazard ratio [HR] 1.82, p < 0.001; LVEF: HR 2.61, p = 0.002, respectively). CONCLUSIONS: Presence of DM was significantly associated with poor outcome after TAVR and adverse effect of DM was remarkable in patients with relatively higher LDL-C levels and reduced LVEF under 40%. These subtypes may need intensive control of cardiovascular risk factors, including DM, before and after TAVR.

Hb A1c Determination by Capillary Electrophoresis is an Efficient Method for Detecting ß-Thalassemias and Hemoglobin Variants.

Glycated hemoglobin (Hb A1c) determination by multicapillary zone electrophoresis (MZE) can additionally be used to detect Hb A2, Hb F and most common hemoglobin (Hb) variants. We assessed the effectiveness of this method for detecting ß-thalassemia (ß-thal), δß-thalassemia (δß-thal) and most common Hb variants. Moreover, Hb F/Hb A2 is evaluated as an index for discriminating between ß- and δß-thal traits. The theoretical ß-thalassemia major (ß-TM) birth rate in our healthcare area is calculated and contrasted with real data. A MZE technique was used for Hb A1c measurements in 27,724 patients. Previous criteria for carrier detection were established and subsequently confirmed by molecular biology techniques. Positive predictive value (PPV) was 100.0%. The prevalence of ß-thal trait (including δß-thal) was 0.34%. The most prevalent mutations (estimated per 100,000 population) were HBB: c.118C > T (57.7%), HBB: c.93-21G>A (50.5%), HBB: c.92 + 1G > A (43.3%), HBB: c.92 + 6T > C (32.5%) and HBB: c.20delA (18.0%) for ß-thalassemias, and Hb S (HBB: c.20A > T) (32.5%) and Hb J-Baltimore (HBB:c.3880T>A) (28.9%) for Hb variants. We found a paradoxical result between the theoretical ß-TM birth rate and real data. We calculated an optimal Hb F/Hb A2 index cutoff of 0.71 for discriminating between ß- and δß-thal traits. This method is highly cost-effective for detecting ß-thalassemias and common Hb variants. Prevalence results match previous data for the Spanish population. Heterogeneity of mutations in Spain has markedly increased as a consequence of migration. The Hb F/Hb A2 index cutoff could be used to predict δß-thal trait.

Hb Belluno [ß111(G13)Val→Gly;ß133(H11)Val→Val (HBB: c.335T > G;402G > C)]: Incidental Detection of a New Clinically Silent ß Chain Variant During Hb A1c Determination by High Performance Liquid Chromatography.

A previously unreported ß chain variant, Hb Belluno [ß111(G13)Val→Gly;ß133(H11)Val→Val (HBB: c.335T > G;402G > C)], was incidentally discovered in a woman suffering from diabetes, during glycated hemoglobin (Hb A1c) assay. Its presence was suspected because of a small abnormal peak with a retention time just shorter than that of normal Hb A1c. Standard high performance liquid chromatography (HPLC), capillary zone electrophoresis (CZE) and agarose gel electrophoresis did not allow to separate the variant from Hb A. The reversed phase HPLC of globin chains showed the presence of a heterozygous ß-globin variant amounting to approximately 43.5% of the total ß chains. Later, this variant was found in five other members of the same family and DNA sequencing analysis confirmed a ß-globin gene mutation. The variant is clinically silent in all patients and showed a slight instability with both heat and isopropanol tests. The other three mutations at this locus also affect stability. Hemoglobin (Hb) variants may invalidate the results of Hb A1c analysis and could result in mismanagement of diabetes. A comment alerting the requesting clinician to the presence of the Hb variant must be appended to the Hb A1c result. Additionally, many Hb variants can be chromatographically and/or electrophoretically silent. Therefore, when the clinician suspects a variant Hb, it is not sufficient to get a negative response from an HPLC screening test to rule it out. A dialogue with the pathologist is essential, involving exchange of information and sharing a diagnostic work-up including surveys to assess Hb stability and oxygen affinity, as much as DNA sequencing.

Description of Three New α Variants and Four New ß Variants: Hb Montluel [α110(G17)Ala → Val; HBA1: c.332C > T], Hb Cap d'Agde [α131(H14)Ser → Cys; HBA2: c.395C > G] and Hb Corsica [α100(G7)Leu → Pro; HBA1: 302T > C]; Hb Nîmes [ß104(G6)Arg → Gly; HBB: c.313A > G], Hb Saint Marcellin [ß112(G14)Cys → Gly; HBB: c.337T > G], Hb Saint Chamond [ß80(EF4)Asn → 0; HBB: c.241_243delAAC] and Hb Dompierre [ß29(B11)Gly → Arg; HBB: c.88G > C].

We present here seven new hemoglobin (Hb) variants identified during routine Hb analysis. All of them are caused by a missense mutation except Hb Saint Chamond, which results from an in-frame deletion of the asparagine residue at ß80. All these variants are clinically silent in the heterozygous state but two of them (Hb Cap d'Agde and Hb Dompierre) may be unstable, whereas Hb Nîmes could present a very slightly elevated oxygen affinity. These data are to be confirmed by appropriate biochemical tests.

A novel hemoglobin variant found on the α1 chain: Hb KSVGH (HBA1: p.Lys57_Gly58insSerHisGlySerAlaGlnValLys).

Glycosylated hemoglobin (Hb A1C) is a crucial indicator for the long-term control and the diagnosis of diabetes. However, the presence of hemoglobin (Hb) variants may affect the measured value of Hb A1C and result in an abnormal graph trend and inconsistency between the clinical blood sugar test and Hb A1C values. In this study, laboratory data of 41,267 patients with diabetes were collected. The Hb A1C levels and the graph results were examined. We identified 74 cases containing abnormal Hb A1C graph trends. The conducted blood cell counts and capillary Hb electrophoresis were used to analyze Hb variants. We also determined gene variation for the Hb variants by a sequence approach. Fifteen different types of Hb variants were identified in this study. Among these, we found a novel variant in which the α1 subunit of Hb showed an insertion of 24 nucleotides (nts) between the 56th and 57th residues. We named this novel variant Hb Kaohsiung Veterans General Hospital (Hb KSVGH) (HBA1: p.Lys57_Gly58insSerHisGlySerAlaGlnValLys).

Evaluation of HLC-723 G7 Hemoglobin A1c Autoanalyzer / 임상검사와정도관리

BACKGROUND: We evaluated the performance and analysis time of HLC-723 G7 (Tosoh corp. Tokyo, Japan) hemoglobin (Hb) A1c autoanalyzer. It utilizes cation exchange high performance liquid chromatography (HPLC) method and has a reduced analysis time compared with that of an earlier model HLC-723GHb V A1c 2.2(TM) (HLC-723GHb V, Tosoh corp. Tokyo, Japan). METHODS: We evaluated linearity, precision and comparison with HLC-723GHb V following NCCLS guidelines and counted the number of tests per hour to estimate analysis time. RESULTS: Linearity through the range from 5.8% to 13.9% was good (r2=0.9930, relative nonlinearity <2.5%). The within-run coefficients of variation (CVs) for groups of low, middle, and high level were 1.09%, 0.76%, and 0.68% and total CVs for each group were 1.60%, 0.91%, and 1.00%, respectively. Correlation equation between HLC-723 G7 and HLC-723GHb V was HLC-723 G7=1.0308 (HLC-723GHb V)-0.2896 %Hb A1c (r=0.9992, P<0.0001). Analysis time of HLC-723 G7 was 1.2 minutes per test compared with 2.1 minutes of HLC-723GHb V. CONCLUSIONS: HLC-723 G7 showed the acceptable performance and shortening analysis time therefore, it was suitable for reducing turn around time of Hb A1c assay.

Evaluation of VARIANTTM II Hemoglobin A1c Autoanalyzer / 대한임상병리학회지

BACKGROUND: We evaluated newly introduced VARIANTTM II(Bio-Rad Laboratories, CA, USA) hemoglobin(Hb) A1c autoanalyzer, including bar code reading, cap-piercing system and automatic hemolyzing. It utilizes ion-exchange high performance liquid chromatography(HPLC) method. METHODS: Linearity, precision, comparison with Hi-AUTOA1cTM HA-8121(Kyoto Daiichi, Kagaku Co. Ltd, Kyoto, Japan) and analysis time were evaluated. The reference range was determined by VARIANTTM II from 120 healthy subjects. RESULTS: Linearity through the range from 5.8% to 14.7% was good(r2=0.9909). The within-run coefficients of variation(CVs) for groups of low, middle and high level were 3.07%, 1.96% and 2.14% and between-day CVs for each group were 2.35%, 3.09% and 2.10%, respectively. Correlation equation between VARIANTTM II and Hi-AUTOA1cTM HA-8121 was VARIANTTM II = 1.0886(Hi-AUTOA1cTM HA-8121) + 0.4760% Hb A1c(r=0.9906). Two instruments were also compared by Altman and Bland's method and mean bias was 1.20. Analysis time of VARIANTTM II was 15.6 tests per hour compared with 14.8 tests of Hi-AUTOA1cTM HA-8121. The reference range in this study was 2.8-5.9% Hb A1c. CONCLUSIONS: VARIANTTM II showed the acceptable performance and advantage of calibration, and it was suitable for routine use in the clinical laboratory.