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Hereditary Disorders of Red Cell Permeability

  • Author: Vikramjit S Kanwar, MBBS, MBA, MRCP(UK), FAAP; Chief Editor: Max J Coppes, MD, PhD, MBA  more...
Updated: Feb 19, 2014


Abnormalities of red cell membrane cation permeability are seen in several hereditary disorders. These dominantly inherited conditions are collectively called the hereditary stomatocytoses and allied disorders. This class of hemolytic anemias is clinically diverse.[1] See image below.

Hereditary stomatocytosis. Courtesy of Jean A. Sha Hereditary stomatocytosis. Courtesy of Jean A. Shafer, BS, MA, Assistant Professor of Hematology and Pathology at the University of Rochester School of Medicine and Dentistry.

Overhydrated hereditary stomatocytosis (OHSt), also called hydrocytosis, was the first of these disorders to be described.[2] An abnormally increased cation influx results in swollen erythrocytes, hemolysis, and stomatocytes. At the other end of the spectrum, net loss of cations and water results in dehydrated hereditary stomatocytosis (DHSt), also called xerocytosis.

Intermediate syndromes that are asymptomatic or have mixed features, such as cryohydrocytosis (CHC) and familial pseudohyperkalemia (FP), have also been described.

CHC has been linked to mutations in the band 3 chloride-bicarbonate exchanger AE1.[3] DHSt and most cases of FP have been mapped to the 16q23-24 genetic locus.[4] OHSt has been linked to mutations in the erythroid ammonia channel Rh-associated glycoprotein (RHAG),[5] the erythroid chloride/bicarbonate exchanger SLC4A1/AE1/band 3, and the erythroid glucose transporter SLC2A1/GLUT1; in Schnauzer dogs, OHSt is asymptomatic and involves none of these genes.[6] Decreases in stromatin, or protein 7.2b, seen in OHSt are thought to be a trafficking alteration.[7]



Erythrocytes have intracellular hemoglobin, 2-3,diphosphoglycerate (2,3-DPG), and ATP, which all exert osmotic pressure across the semipermeable cell membrane. By transporting Na+ and K+ ions across the cell membrane, red cells can adjust the intracellular concentration of these cations and regulate intracellular hydration. Any disturbances in membrane cation permeability alter cellular hydration and can cause numerous effects, including hemolysis.

In overhydrated hereditary stomatocytosis, the major defect is a marked asymmetric increase in passive Na+ and K+ permeability. The influx of Na+ exceeds the loss of K+, causing a net influx of water, overhydration, and swelling. The resulting hydrocytosis leads to increased osmotic fragility and decreased deformability, with consequent hemolysis. Some cases are now linked to mutations of the Rh-associated glycoprotein (RHAG) gene,[5] and decreases in stomatin, or protein 7.2b, are thought to be a trafficking alteration.[7]

In contrast, the primary abnormality in dehydrated hereditary stomatocytosis is a change in the relative membrane permeability to K+. Efflux of K+ is increased 2-fold to 4-fold and results in cation depletion, with decreased intracellular osmolality and water loss. The xerocytes formed are shear-sensitive and prone to membrane fragmentation in response to metabolic stress, with subsequent hemolysis. FP is usually asymptomatic or rarely shows mild macrocytosis. When erythrocytes are cooled to room temperature or lower (eg, after phlebotomy), the net K+ leak is greater than expected and results in factitious hyperkalemia.[8, 9] Dehydrated hereditary stomatocytosis and most cases of FP have been mapped to the 16q23-24 genetic locus.[4]

CHC clinically manifests with mild hemolytic anemia and is remarkable for an abnormality of the band 3 chloride-bicarbonate exchanger AE1.[3] At low temperatures, the defective anion channel appears to allow a significant cation leak, and autohemolysis may be seen in vitro at 4ºC. The molecular defects that transform AE1 into a cation channel are currently under investigation.[10]





These hereditary syndromes are extremely rare, and accurate data concerning their prevalence are lacking; however, overall they are thought to be 40-50 times less common than hereditary spherocytosis.[11] Dehydrated hereditary stomatocytosis (DHSt) is reported in 1 per 50,000 live births.[12] and DHSt kindreds in Ireland[13] and France[14] have been reported.


Morbidity in these disorders depends on the severity of the hemolytic anemia. The risks for neonatal hyperbilirubinemia with kernicterus are similar to those of other hemolytic anemias. Exchange transfusion is occasionally required. Aplastic crises associated with parvovirus infection occur, although they are infrequent. Both OHSt and DHSt are associated with a significant risk of serious thrombosis after splenectomy, although the reason for this is unknown.

Most patients with overhydrated hereditary stomatocytosis have chronic low-grade anemia punctuated by recurrent episodes of more severe anemia and jaundice. Other patients have a much milder disease. Iron overload, regardless of transfusion status, is now well recognized.

Most patients with dehydrated hereditary stomatocytosis are asymptomatic but experience mild-to-moderate hemolytic anemia, which is generally well compensated. Hydrops fetalis and neonatal ascites have been reported in a few kindreds.[15] Exchange transfusions are occasionally required. Even simple transfusions carry risks of infection, allergic reactions, and febrile or hemolytic transfusion reactions.


Most patients with hereditary disorders of red cell permeability are of European descent.


These syndromes have no known sex predilection, and clinical manifestations are not affected by sex.

Contributor Information and Disclosures

Vikramjit S Kanwar, MBBS, MBA, MRCP(UK), FAAP Professor of Pediatrics, Albany Medical College; Chief, Division of Pediatric Hematology-Oncology, John and Anna Landis Endowed Chair for Pediatric Hematology-Oncology, Medical Director, Melodies Center for Childhood Cancer and Blood Disorders, Albany Medical Center

Vikramjit S Kanwar, MBBS, MBA, MRCP(UK), FAAP is a member of the following medical societies: American Academy of Pediatrics, American Society of Hematology, American Society of Pediatric Hematology/Oncology, Children's Oncology Group, International Society of Pediatric Oncology

Disclosure: Nothing to disclose.


Richard H Sills, MD Professor of Pediatrics, Upstate Medical University

Richard H Sills, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Society of Hematology, American Society of Pediatric Hematology/Oncology

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

James L Harper, MD Associate Professor, Department of Pediatrics, Division of Hematology/Oncology and Bone Marrow Transplantation, Associate Chairman for Education, Department of Pediatrics, University of Nebraska Medical Center; Associate Clinical Professor, Department of Pediatrics, Creighton University School of Medicine; Director, Continuing Medical Education, Children's Memorial Hospital; Pediatric Director, Nebraska Regional Hemophilia Treatment Center

James L Harper, MD is a member of the following medical societies: American Society of Pediatric Hematology/Oncology, American Federation for Clinical Research, Council on Medical Student Education in Pediatrics, Hemophilia and Thrombosis Research Society, American Academy of Pediatrics, American Association for Cancer Research, American Society of Hematology

Disclosure: Nothing to disclose.

Chief Editor

Max J Coppes, MD, PhD, MBA Executive Vice President, Chief Medical and Academic Officer, Renown Heath

Max J Coppes, MD, PhD, MBA is a member of the following medical societies: American College of Healthcare Executives, American Society of Pediatric Hematology/Oncology, Society for Pediatric Research

Disclosure: Nothing to disclose.

Additional Contributors

J Martin Johnston, MD Associate Professor of Pediatrics, Mercer University School of Medicine; Director of Hematology/Oncology, The Children's Hospital at Memorial University Medical Center; Consulting Oncologist/Hematologist, St Damien's Pediatric Hospital

J Martin Johnston, MD is a member of the following medical societies: American Academy of Pediatrics, American Society of Pediatric Hematology/Oncology, International Society of Paediatric Oncology

Disclosure: Nothing to disclose.

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Hereditary stomatocytosis. Courtesy of Jean A. Shafer, BS, MA, Assistant Professor of Hematology and Pathology at the University of Rochester School of Medicine and Dentistry.
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