Increasing recognition of haemoglobin Le Lamentin

A New α1-Globin Variant, Hb Ormylia [HBA1:c.63C > G; p.His21Gln]. Report of Eleven Cases in Northern Greece

The first identification of a novel α1-Globin variant, Hb Ormylia in 11 Greeks originating from a small village, Ormylia, Chalkidiki, Greece is reported. The new genetic variant leads to the production of a hemoglobin variant that can be identified and quantified by High-Performance Liquid Chromatography. Capillary and classic electrophoresis were not informative. Direct DNA sequencing revealed a new mutation C > G mutation at codon 21 of α1 gene (His > Gln). The new variant has been named Hb Ormylia and this is the first description of this genetic variant of α1 gene in the literature.

Hemoglobin Le Lamentin in the province of Albacete, Spain: Discovery of 32 cases

OBJECTIVES

Hemoglobin Le Lamentin (α20(B1)His→Gln) is a ubiquitous variant that has been previously described in a small number of isolated patients. We report the incidental observation of Hb Le Lamentin in a large population from the province of Albacete, in southeastern Spain. Our study investigates possible reasons for the elevated number of carriers of this variant and its implications for the management of diabetes in our region.

DESIGN & METHODS

The subjects are 32 diabetic patients whose hemoglobin displayed an unusual peak while they were being tested for glycated hemoglobin at the laboratory of the University General Hospital of Albacete over a 3-year period. Measurements were made by high performance liquid chromatography using a Variant™ II Turbo Kit-2.0, and subsequently the samples of the 32 patients with anomalous peaks were sent to the Hospital Clínico San Carlos (Madrid, Spain) for molecular characterization of any Hb variants.

RESULTS

Molecular studies revealed 31 out of 32 patients heterozygous for Le Lamentin, and in one of them, Hb City of Hope was associated with Hb Le Lamentin. The remaining patient was homozygous for the Le Lamentin mutation. Additionally, most patients were native to the northeastern half of the province of Albacete and were unrelated.

CONCLUSIONS

Our study describes the largest finding to date of hemoglobin Le Lamentin in a sample of patients. The fact that our region has been perpetually depopulated, with a population that has remained stable in small localities over the centuries, may have favored the survival of the mutation. Since the presence of this variant underestimates the true value of glycated hemoglobin measured by HPLC, it is necessary to systematically review chromatograms.

Different forms of Hb Le Lamentin. An unexpected finding in Hba1c quantification

OBJECTIVES

Glycated hemoglobin (HbA1c) is accepted as the most trusted marker for monitoring patients with diabetes mellitus. Ion-exchange high-performance liquid chromatography (HPLC) is one of the most widely used methods for HbA1c analysis. The presence of a hemoglobin variant can interfere with HbA1c quantification, requiring other analyses to clarify the results.Herein, we present two cases of Hb Le Lamentin, which, although they were the same variant, were thought to correspond to different hemoglobinopathies because of their percentages.

DESIGN AND METHODS

Two male patients presented with an anomalous peak between HbA1c and HbA0 during a routine analysis of HbA1c using ion-exchange HPLC (Variant™ II Turbo).The hemoglobin variants were studied using capillary zone electrophoresis with the Sebia system, and the globin chains were analyzed by reverse-phase HPLC. A genetic analysis was performed using automated sequencing of the α2 and β genes.

RESULTS

In this work, we describe the first case of homozygous Hb Le Lamentin and the first double-heterozygous case of Hb Le Lamentin/Hb City of Hope.

CONCLUSIONS

Although the presence of these variants does not lead to clinical anomalies, it also does not affect hematologic parameters. The variants have an impact on the determination of glycated hemoglobin levels using ion-exchange HPLC because the retention time interferes with the elution time of HbA1c, resulting in a falsely reduced value. Therefore, it is necessary to either recalculate the result or use another measurement method.

A new α1-globin mutation, Hb Brugg [α20(B1)His→Gln]

A 2½-year-old male child and a 23-year-old woman with no clinical symptoms were investigated during routine consultations. Cation exchange high performance liquid chromatography (HPLC) revealed an additional peak eluting before Hb A. DNA sequencing showed a novel heterozygous mutation at codon 20 of the α1-globin gene. The hemoglobin (Hb) variant was named Hb Brugg. Analysis of oxygen affinity Hb and Hb stability did not show any changes compared to normal Hb constellation.

The number of unexpected HbA variants may be a greater problem in routine practice than is generally realized

BACKGROUND

The majority of variant and abnormal haemoglobins are clinically silent but may not be biochemically silent when it comes to HbA1c estimation.

CASE REPORT

We describe several cases in which there were problems in the determination of HbA1c for monitoring diabetes in patients that would not normally be classified as being at risk. Four of these cases were sufficiently unusual to warrant individual publication but all came from a very restricted geographical area with a population of only approximately 500,000. The significance of this is not that variant haemoglobins affect HbA1c analysis but that the occurrence of unexpected/unusual variant haemoglobins may be more frequent than most clinicians would expect, considering that only a small proportion of the basal population are diabetic and have their HbA1c monitored. Differences will exist between different areas due to differences in both the prevalence of variants and the analytical methods employed.

CONCLUSIONS

Consequently, we propose greater interaction between diabetologists and the laboratory in an attempt to identify these clinically but not biochemically silent variants to achieve a true estimation of the glycaemic control in affected patients.