NIH Rare Diseases
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53
The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.Orpha Number: 3202Disease definitionDehydrated hereditary stomatocytosis (DHS) is a rare hemolytic anemia characterized by a decreased red cell osmotic fragility due to a defect in cation permeability, resulting in red cell dehydration and mild to moderate compensated hemolysis. Pseudohyperkalemia (loss of potassium ions from red cells on storage at room temperature) is sometimes observed.EpidemiologyThe prevalence of DHS is unknown but to date, about 20 families with DHS have been described in the literature.Clinical descriptionThe clinical presentation of the disease is very heterogeneous. Onset of DHS may occur during the perinatal period with occurrence of edema and ascites (most often not related to an underlying anemia) that usually resolve spontaneously during the first weeks of life but may rarely lead to hydrops fetalis (see this term). Most adult patients present a mild anemia or a totally compensated hemolysis, with fatigue, icterus, splenomegaly and risks of secondary complications including cholelithiasis. Patients can also be referred for unexplained hemochromatosis, since iron overload is frequently associated with the disease. Thrombotic complications (arterial and venous events, including portal vein thrombosis (see this term) and pulmonary hypertension) have been described at a high rate after splenectomy.EtiologyMost reported DHS cases are caused by gain-of-function mutations in the genePIEZO1 (16q24.3) which encodes part of a mechanosensitive ion channel. This results in increased red cell membrane permeability for cations that consequently leads to cation depletion, dehydration and shortened red cell survival. Rare atypical forms have been associated with mutations in SLC4A1 (17q21.31), coding for the Band 3 anion transport protein, or KCNN4 (19q13.2) which codes for the putative Gardos channel.Diagnostic methodsDiagnosis relies on laboratory findings. The typical presentation includes normal hemoglobin level or mild anemia, normal mean cell volume (MCV) or mild macrocytosis, normal or elevated mean corpuscular hemoglobin concentration (MCHC), elevated reticulocytosis, and a small number of stomatocytes (in vitro leakage and is clinically irrelevant. Measurement of ferritin level and liver magnetic resonance imaging (MRI) are performed to evaluate iron overload. Genetic screening of the causative genes can be performed after phenotypic investigations.Differential diagnosisDifferential diagnoses include other causes of hemolysis, including hereditary spherocytosis, overhydrated hereditary stomatocytosis, hemoglobinopathy or red cell enzyme deficiencies such as hemolytic anemia due to red cell pyruvate kinase deficiency (see these terms).Genetic counselingTransmission is autosomal dominant and genetic counseling should be offered to affected families.Management and treatmentTreatment is mainly symptomatic. Occurrence of cholelithiasis should be regularly monitored. Folic acid supplementation should be proposed in case of anemia. Pregnancy should be closely monitored. Iron status should be regularly monitored by serum ferritinemia and liver MRI. Iron depletion, most often by phlebotomy, is proposed when ferritinemia reaches the threshold of 1000 ng/ml or when iron liver overload is present. Splenectomy is contraindicated in DHS due to an elevated risk of life threatening arterial and venous thrombotic events.PrognosisOverall prognosis is favorable in well managed patients (not splenectomized and with regular monitoring of their iron status). Splenectomized patients are at risk of early or late thrombotic events.Visit the Orphanet disease page for more resources.
MalaCards based summary
:
Dehydrated Hereditary Stomatocytosis 1 with or Without Pseudohyperkalemia and/or Perinatal Edema, also known as
dehydrated hereditary stomatocytosis, is related to
dermatitis herpetiformis and
dermatitis herpetiformis, familial. An important gene associated with Dehydrated Hereditary Stomatocytosis 1 with or Without Pseudohyperkalemia and/or Perinatal Edema is
PIEZO1 (Piezo Type Mechanosensitive Ion Channel Component 1). Affiliated tissues include
spleen,
liver and
heart, and related phenotypes are
jaundice and
pallor
OMIM
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57
Dehydrated hereditary stomatocytosis (DHS), also known as hereditary xerocytosis, is an autosomal dominant hemolytic anemia characterized by primary erythrocyte dehydration. DHS erythrocytes exhibit decreased total cation and potassium content that are not accompanied by a proportional net gain of sodium and water. DHS patients typically exhibit mild to moderate compensated hemolytic anemia, with an increased erythrocyte mean corpuscular hemoglobin concentration and a decreased osmotic fragility, both of which reflect cellular dehydration (summary by Zarychanski et al., 2012). Patients may also show perinatal edema and pseudohyperkalemia due to loss of K+ from red cells stored at room temperature. A minor proportion of red cells appear as stomatocytes on blood films. Complications such as splenomegaly and cholelithiasis, resulting from increased red cell trapping in the spleen and elevated bilirubin levels, respectively, may occur. The course of DHS is frequently associated with iron overload, which may lead to hepatosiderosis (summary by Albuisson et al., 2013).
The 'leaky red blood cells' in familial pseudohyperkalemia show a temperature-dependent loss of potassium when stored at room temperature, manifesting as apparent hyperkalemia. The red blood cells show a reduced life span in vivo, but there is no frank hemolysis. Studies of cation content and transport show a marginal increase in permeability at 37 degrees C and a degree of cellular dehydration, qualitatively similar to the changes seen in dehydrated hereditary stomatocytosis. Physiologic studies show that the passive leak of potassium has an abnormal temperature dependence, such that the leak is less sensitive to temperature than that in normal cells (summary by Iolascon et al., 1999).
Carella et al. (2004) noted that 3 clinical forms of pseudohyperkalemia unassociated with hematologic manifestations, based predominantly on the leak-temperature dependence curve, had been reported: (1) pseudohyperkalemia Edinburgh, in which the curve has a shallow slope; (2) pseudohyperkalemia Chiswick or Falkirk (see 609153), in which the curve is shouldered; and (3) pseudohyperkalemia Cardiff (see 609153), in which the temperature dependence of the leak shows a 'U-shaped' profile with a minimum at 23 degrees C. Gore et al. (2004) stated that potassium-flux temperature profiles are consistent both from year to year in an individual as well as consistent within affected members of a pedigree.
(194380)
UniProtKB/Swiss-Prot
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75
Dehydrated hereditary stomatocytosis 1 with or without pseudohyperkalemia and/or perinatal edema: An autosomal dominant hemolytic anemia characterized by primary erythrocyte dehydration. DHS erythrocytes exhibit decreased total cation and potassium content that are not accompanied by a proportional net gain of sodium and water. DHS patients typically exhibit mild to moderate compensated hemolytic anemia, with an increased erythrocyte mean corpuscular hemoglobin concentration and a decreased osmotic fragility, both of which reflect cellular dehydration. Patients may also show perinatal edema and pseudohyperkalemia due to loss of potassium from red cells stored at room temperature. A minor proportion of red cells appear as stomatocytes on blood films. Complications such as splenomegaly and cholelithiasis, resulting from increased red cell trapping in the spleen and elevated bilirubin levels, respectively, may occur. The course of DHS is frequently associated with iron overload, which may lead to hepatosiderosis.
