Hemoglobin C trait accentuates erythrocyte dehydration in hereditary xerocytosis

A 17-year-old male presented with acute hemolysis with stomatocytosis, elevated mean corpuscular hemoglobin concentration (MCHC), and osmotic gradient ektacytometry consistent with marked erythrocyte dehydration. Erythrocytes from both parents also demonstrated evidence of dehydration with elevated MCHC and abnormal ektacytometry, but neither to the degree of the patient. Genetic studies revealed the patient had hereditary xerocytosis (HX) due to a novel PIEZO1 mutation inherited from his mother and hemoglobin C (HbC) trait inherited from his father. HbC trait accentuated the erythrocyte dehydration of HX. Coinheritance of interrelated disorders and/or modifier alleles should be considered whenever severe erythrocyte dehydration is observed.

Hemoglobin C Trait Provides Protection From Clinical Falciparum Malaria in Malian Children

Background. Hemoglobin C trait, like hemoglobin S trait, protects against severe malaria in children, but it is unclear whether hemoglobin C trait also protects against uncomplicated malaria. We hypothesized that Malian children with hemoglobin C trait would have a lower risk of clinical malaria than children with hemoglobin AA.

Methods. Three hundred children aged 0–6 years were enrolled in a cohort study of malaria incidence in Bandiagara, Mali, with continuous passive and monthly active follow-up from June 2009 to June 2010.

Results. Compared to hemoglobin AA children (n = 242), hemoglobin AC children (n = 39) had a longer time to first clinical malaria episode (hazard ratio [HR], 0.19; P = .001; 364 median malaria-free days vs 181 days), fewer episodes of clinical malaria, and a lower cumulative parasite burden. Similarly, hemoglobin AS children (n = 14) had a longer time to first clinical malaria episode than hemoglobin AA children (HR, 0.15; P = .015; 364 median malaria-free days vs 181 days), but experienced the most asymptomatic malaria infections of any group.

Conclusions. Both hemoglobin C and S traits exerted a protective effect against clinical malaria episodes, but appeared to do so by mechanisms that differentially affect the response to infecting malaria parasites.

Novel Insights Into the Protective Role of Hemoglobin S and C Against Plasmodium falciparum Parasitemia

Although hemoglobin S (HbS) and hemoglobin C (HbC) are well known to protect against severe Plasmodium falciparum malaria, conclusive evidence on their role against infection has not yet been obtained. Here we show, in 2 populations from Burkina Faso (2007-2008), that HbS is associated with a 70% reduction of harboring P. falciparum parasitemia at the heterozygous state (odds ratio [OR] for AS vs AA, 0.27; 95% confidence interval [CI], .11-.66; P = .004). There is no evidence of protection for HbC in the heterozygous state (OR for AC vs AA, 1.49; 95% CI, .69-3.21; P = .31), whereas protection even higher than that observed with AS is observed in the homozygous and double heterozygous states (OR for CC + SC vs AA, 0.04; 95% CI, .01-.29; P = .002). The abnormal display of parasite-adhesive molecules on the surface of HbS and HbC infected erythrocytes, disrupting the pathogenic process of sequestration, might displace the parasite from the deep to the peripheral circulation, promoting its elimination at the spleen level.

Staged single-ventricle palliation in an infant with hemoglobin SC disease

Staged single-ventricle palliation is used to treat many cyanotic congenital heart diseases. Hemoglobin sickle cell disease is associated with anemia and significant vascular sickling sequelae, which increase the risk associated with single-ventricle palliation. To our knowledge, there are no reports in the English-language medical literature of single-ventricle palliation having been performed on a patient who had either sickle cell anemia or sickle cell-hemoglobin C disease. Herein, we discuss our clinical and surgical management of an infant with tricuspid atresia type IA and hemoglobin sickle cell disease who survived single-ventricle palliative procedures through the 2nd stage of a bidirectional Glenn anastomosis.