Thrombosis risk with haemoglobin C trait and haemoglobin C disease: A systematic review

The thrombotic risk with haemoglobin C trait (HbAC) or haemoglobin C disease (HbCC) is unclear. However, individuals with HbCC have demonstrated chronic haemolysis, higher blood viscosity and altered rheology when compared to individuals with wild-type haemoglobin (HbAA). These physiological alterations may theoretically translate to increased risk of thrombosis; therefore, a systematic literature review was performed to investigate the possible association between HbAC and/or HbCC and thrombosis. Twenty-two studies met inclusion criteria representing 782 individuals with HbAC (n = 694) or HbCC (n = 88). Fifteen studies described the presence/absence of venous thromboembolism (VTE) in patients with HbAC (n = 685) or HbCC (n = 79), while seven studies described patients with HbAC (n = 9) or HbCC (n = 9) and arterial thrombosis. Most (n = 20) studies were case reports or case series; however, two studies suggested a potential increased VTE risk with HbAC compared to HbAA in (i) all patients (OR 2.2, 95% CI: 0.9-5.5) and in (ii) pregnant individuals (RR 3.7, 95% CI 0.9-16). This review is the largest assessment of patients with HbC trait or disease and thrombosis to date; despite its limitations, the findings suggest HbC may be a predisposing risk factor to thrombosis. Prospective cohort studies are warranted to definitively elucidate the risk of thrombosis in this population.

Hemoglobinopathies in pregnancy

Sickle cell trait is associated with an increased incidence of asymptomatic bacteriuria, low birth weight infants and premature rupture of membranes. Hemoglobin SS and hemoglobin SC in pregnancy result in significantly increased maternal morbidity and mortality and reproductive wastage. Heterozygous thalassemias in pregnancy carry increased risks but to a lesser degree than hemoglobins SS and SC. Partial exchange transfusion can provide effective prophylaxis for many of the maternal and fetal problems of sickle cell disease.

Haemoglobin C and haemoglobin O Arab-thalassaemia in families of Greek origin

A case of Haemoglobin C trait and a family with Haemoglobin O Arab thalassaemia from Greece are described. Both Haemoglobin C and Haemoglobin O Arab were identified by peptide analysis.

Anaesthesia in sickle-cell states: a plea for simplicity

505 patients with various haemoglobinopathies were given a general anaesthetic between January 1970 and February 1972. One patient with haemoglobin SC disease and one patient with sickle-cell trait (HbAS) died postoperatively. Four other patients who were sickling positive, but whose genotypes were unknown, died, one from sickle-cell crisis precipitated by haemorrhage.A simple anaesthetic technique together with good postoperative care can provide safe general anaesthesia for patients with sickle-cell states. A plea is made for simplicity in the anaesthetic management of these patients.

The sickle-cell and altitude

High altitude seemed to be responsible for seven recent cases of sickling crisis. People with sickle-cell trait are at risk if they fly in unpressurized aircraft, which are used for many local air services. Those with sickle-cell haemoglobin C disease should avoid air travel even in pressurized aircraft. Possibly as a result of "autosplenectomy," patients with sickle-cell anaemia seem to be able to fly in pressurized aircraft with little risk. All passengers and aircrew who might have some form of sickle-cell disease should be screened before flight.

Sickle-cell disease in pregnant immigrants

Thirteen pregnancies in nine patients with sickle-cell disease, sickle-cell/haemoglobin C disease and sickle-cell/thalassaemia are reported. There was one maternal death and one stillbirth. Crises occurred in three of the four patients with sickle-cell disease but in only one of the three patients with sickle-cell/haemoglobin C disease.

Pathogenesis of hemolytic anemia in homozygous hemoglobin C disease

Hemoglobin C is less soluble than hemoglobin A in red cells, in hemolysates, and in dilute phosphate buffer. Its relative insolubility may be explained by electrostatic interactions between positively charged beta6-lysyl groups and negatively charged groups on adjacent molecules. Red cells from patients with homozygous hemoglobin C (CC) disease exhibit aberrant physical properties which suggest that the cells are more rigid than normal erythrocytes. They pass through membrane filters less readily than normal red cells do, and their viscosity is higher than that of normal cells. Differences from normal cells are exaggerated if mean corpuscular hemoglobin concentration (MCHC) is increased, by suspension in hypertonic salt solution. Increased rigidity of CC cells, by accelerating their fragmentation, may be responsible for formation of microspherocytes. These small dense cells are exceptionally rigid, and probably are even more susceptible to fragmentation and sequestration. Rigidity of CC cells can be attributed to a "precrystalline" state of intracellular hemoglobin, in which crystallization does not occur, although the MCHC exceeds the solubility of hemoglobin in hemolysates.

The Coexistence of Acute Rheumatic Fever and Sickle Cell-Hemoglobin C Disease

The clinical and postmortem findings in a case of sickle cell-hemaglobin C disease complicated by acute rheumatic fever with accompanying carditis, and rheumatic pneumonitis are presented and discussed. This is believed to be the first such case reported.

The recent literature pertaining to the cardiac manifestations of SS and SC hemoglobinopathies is briefly reviewed.

A possible explanation for the failure of the rheumatic process to respond to conventional therapy in our patient is given.

HEMOGLOBIN C DISEASE IN A SICILIAN-CANADIAN FAMILY

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Sickle cell hemoglobin-C disease. Two case reports

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