Hb Volga or alpha 2 beta 2 27(B9)Ala----Asp in an Italian family

Thrombosis Tendency After Splenectomy in a Danish Family With Hemoglobin Volga, and a Literature Review

Hemoglobin (Hb) Volga is a rare, unstable β-chain hemoglobin variant (β27 Ala→Asp), causing chronic hemolytic anemia. This study presents two members of a Danish family, splenectomized due to Hb Volga at and with multiple thrombotic events. The proband was diagnosed with Hb Volga 9 years old and splenectomy was performed as a part of treatment. Throughout his life, he experienced multiple superficial thrombophlebitis, two episodes of distal deep venous thrombosis (DVT) on lower extremities (age 32 and 33) and a transient ischemic attack (TIA) presented as amaurosis fugax (age 51). Thrombophilia investigation was normal. The proband's son was diagnosed with Hb Volga and underwent splenectomy at the age of 6. Despite anticoagulation therapy, he suffered from multiple venous thromboembolic events in his youth and died of chronic pulmonary embolism (PE)/pulmonary hypertension combined with infection. Given the observed propensity for multiple thromboses in these two patients, a literature review was conducted investigating reported occurrence of thrombotic events in individuals with Hb Volga.

Currently 25 cases of Hb Volga are reported worldwide. The clinical symptoms primarily described are related to hemolytic anemia. Splenectomy is reported in 15 patients. Thromboses have previously been reported in only three patients who were also splenectomized. These cases involved DVT and PE, myocardial infarction, and an unspecified thrombotic event. The proband represents the first reported Hb Volga case with both venous and arterial thrombotic disorders. The exact mechanism underlying thrombotic tendency in patients with Hb Volga remains unknown, but it is probably associated with splenectomy.

Hemoglobinopathies mimicking Hb S/beta-thalassemia: Hb S/S with alpha-thalassemia and Hb S/Volga

There are approximately 1200 known natural mutations of the human globin genes. In most clinical laboratories, the diagnosis of hemoglobin disorders is based on blood counts, hemoglobin electrophoresis, or column chromatography, which can identify common variant hemoglobins such as Hb S, C, and E, but are unable to definitively diagnose most other hemoglobin variants and thalassemia mutations. We report two unrelated cases, both thought initially to have Hb S/beta-thalassemia. Subsequent mutational analyses revealed that one is Hb S/S with compound heterozygosity for nondeletional alpha-thalassemia mutations. The other is the first reported case of compound heterozygosity for Hb S and an unstable hemoglobin, Hb Volga. Correct diagnoses of these hereditary disorders are needed for prognosis and proper management and also for genetic counseling. These studies underscore the importance to correlate clinical course with laboratory diagnosis and to make DNA-based diagnostics more widely available for patients with unusual or complicated hemoglobin disorders.

Severe hemolytic anemia associated with Hb Volga [beta27(B9)Ala-->Asp]: GCC-->GAC at codon 27 in a Turkish family

A boy presented at age 4 years with severe congenital hemolytic anemia characterized by highly elevated reticulocyte count (30-50%) and prominent basophilic stippling. Hb had been 4 g/dL at age 7 months. The patient was on a monthly transfusion regimen up to the age of 7 years, when he underwent splenectomy. After removal of the spleen, his Hb stabilized at 11 g/dL. No abnormal pattern was detected in hemoglobin electrophoresis at pH 9 and 6. In-vitro globin synthesis revealed the presence of an abnormal beta-chain in front of the gamma-chain. The beta(A)/beta(X) ratio was 0.77 at 30 min and 0.74 at 2 hr of incubation. Molecular analysis revealed that the patient had GCC-->GAC alteration at codon 27 (beta27(B9)Ala-->Asp) causing the abnormal hemoglobin Volga. The beta-cDNA derived from the beta-Hb Volga allele could be differentiated from HbA beta-cDNA on silver-stained gel. No imbalance in the mRNA of beta(A)/beta(Hb Volga) ratio was observed.

Hb Volga [beta 27(B9)Ala-->Asp]: detection of a de novo mutation by Ava II digestion of PCR-amplified DNA

Hb Volga was observed as a de novo mutation in a 5-year-old boy from Tuzla, Bosnia and Hercegovina, who exhibited severe Heinz body hemolytic anemia. The variant was detected and quantitated at 10.6% by a reversed phase high performance liquid chromatography (HPLC) procedure. Structural characterization was done by HPLC analysis. An easier approach for the detection of Hb Volga by Ava II digestion of polymerase chain reaction-amplified DNA is described.

Influence of splenectomy on the properties of erythrocytes with hemoglobin Volga disease

Hemoglobin Volga is a rare unstable hemoglobin in which there is a replacement of an internal alanine residue, beta 27 (B9), by an aspartate. From a clinical point of view it is characterized by a moderately severe Heinz body hemolytic anemia. A possible clue to the cause of the hemolysis is the increased vulnerability to oxidation of Hb Volga, with increased free radical turnover and consequent damage to the red cell membrane. Splenectomy performed on carriers of Hb Volga may have a positive outcome leading to improvements in both the clinical condition of the patient and hematological variables such as hemoglobin concentration and bilirubin concentration. With the aim of defining a more complete biochemical picture of the beneficial effect of splenectomy in this disease, we have evaluated some enzymic activities of the red cells of a young patient with Hb Volga disease, before and after splenectomy. In particular, we have investigated the activity of superoxide dismutase (superoxide: superoxide oxidoreductase), glutathione peroxidase (GSH peroxidase, glutathione: hydrogen-peroxidase oxidoreductase) and catalase (hydrogen-peroxide: hydrogen-peroxide oxidoreductase) that catalyze reactions relevant to the steady-state concentration of potentially toxic oxygen derivatives such as O2- and H2O2. Besides, we have carried out experiments on the erythrocytic membrane to evaluate eventual changes on the chemical (i.e. peroxidation) and physico-chemical (i.e. fluidity) properties following surgery.