Pediatric hereditary spherocytosis
Introduction
Introduction to pediatric hereditary spherocytosis Hereditary spherocytosis (HS) is a hereditary hemolytic disease caused by abnormality of congenital erythrocyte membrane protein. Its main feature is that more small spherical red blood cells are seen in the peripheral blood. Clinically, anemia, jaundice, splenomegaly, spherocytosis in the blood, the course of the disease is chronic anemia and accompanied by repeated acute hemolysis as the main feature. It is now clear that HS is a hereditary disease caused by abnormalities in the erythrocyte membrane protein gene. basic knowledge The proportion of illness: 0.001% Susceptible people: children Mode of infection: non-infectious Complications: gallstones
Cause
Causes of pediatric hereditary spherocytosis
(1) Causes of the disease
The main cause of hemolysis in this disease is erythrocyte membrane abnormality caused by congenital erythrocyte membrane protein gene mutation. The molecular genetic abnormalities of HS mainly include the lack of combination of ankyrin and membrane contractile protein, the lack of 3 protein, the lack of simple membrane contractile protein and 4.2. Protein deficiency, the most common combination of ankyrin and membrane contractile protein, can cause the vertical interaction between the membrane skeleton and the membrane to weaken, so that the membrane lipid bilayer becomes unstable, and some lipids The budding form forms vesicles and is lost, the erythrocyte membrane surface area is reduced, and finally the red blood cells form a small spherical shape. In addition, HS red blood cells (especially red blood cells passing through the spleen) have a certain degree of dehydration and abnormality in monovalent ion permeability, which may also Related to membrane skeleton defects, due to the low volume reserve of spherical cells, the deformation property is thus reduced, and it is difficult to be engulfed and cleared in the spleen marrow by the spleen microcirculation with a diameter much smaller than itself, in the spleen, It may be because the red blood cells are trapped in the spleen marrow for a long time, the red blood cell ATP is insufficiently produced, and the pH value is lowered to make the red fine The cells are more likely to become spherical. In addition, due to the relative lack of ATP in the red blood cells of the disease, the calcium removal effect of red blood cells is weakened, and calcium is deposited on the cell membrane to make the membrane hard, so that it is more likely to be broken in the spleen, and more unbroken red blood cells. After the spleen circulation, the fragility is further increased, the spherical shape is more obvious, and it is easy to be destroyed in the spleen. The experiment proves that the degree of correction of anemia after splenectomy is related to the original lack of erythrocyte membrane contractile protein, and the contractile protein is normal 70%. Postoperative anemia can be completely corrected; for normal 40% to 70%, compensation can be obtained. <Normal 40% of patients still have anemia after surgery, fortunately <40% of cases are often recessive genetic patients, clinically rare.
(two) pathogenesis
Pathophysiology
(1) Change in cation content and permeability: The exchange of substances inside and outside the red blood cells needs to pass through the cell membrane. The concentrations of inorganic ions and sugars inside and outside the red blood cells vary greatly. Their transport has their own mechanisms. Normal red blood cells maintain cells through Na/K pump. Within Na / K normal ratio, every time the Na / K pump is applied, 3 Na pumps out of the cell, and 2 K are pumped into the cells, so that the red blood cells are in a state of high potassium and low sodium, and HS red blood cells, especially from The red blood cells collected by the spleen have abnormal dehydration and abnormal permeability to monovalent ions, which is presumed to be the result of lack of skeleton protein. The pathway of selective loss of potassium and water is activated to cause abnormal dehydration of cells, such as relatively low pH and oxidation of spleen. The damage of the action and the contact of red blood cells in the spleen with macrophages to generate oxygen free radicals can stimulate the K / Cl-coupling device. In addition, in HS red blood cells, the activity of the Na / K pump that regulates the intracellular sodium and potassium content is hyperactive, Because every 2 atoms of potassium are transported into the cell, and 3 sodium atoms are squeezed out of the cell, the function of the pump will cause dehydration of the red blood cells to prevent red blood cell swelling, destruction, and protein. 4.2 Lack of HS red blood cells has an increased anion transport, while spectrin, ankyrin or band 3 deficient HS red blood cell anion delivery is normal or delivery is reduced.
(2) Retention of non-deformed spherical red blood cells in the spleen: The importance of the pathophysiological mechanism of the spleen in the pathogenesis of HS is well known. There are two factors in the selective destruction of HS red blood cells by the spleen: one is the poor deformability of HS red blood cells, and the other is the spleen vascular system. The unique anatomical structure acts as a microcirculator filter. The ratio of surface area to volume of red blood cells is reduced due to the loss of surface material, resulting in poor red blood cell deformability, which is the main factor in the pathogenesis. Normal discoid cells have a rich surface, allowing The red blood cells deform and pass through the narrow microcirculation channel, while the HS red blood cells lack this deformable extra surface. The deformability is worse because the dehydration of the cells is further aggravated. The main part of the red blood cells in the spleen is the wall of the sinus sinus, from the spleen. The blood of the red spleen cord enters the venous circulation. In the spleen of the rat, the length and width of the pores are 2 to 3 m and 0.2 to 0.5 m, respectively, which is about half of the diameter of the red blood cells. The electron fiber photographs of the spleen specimens show only a very small amount. HS red blood cells pass through this site, so anatomy can be observed in the resected spleen Non-deformed position spherocytosis red pulp deposited in the red pulp congestion thicker.
(3) Regulation and destruction of red blood cells by spleen: HS red blood cells will suffer additional damage once they are detained by the spleen due to the loss of surface area and cell density. It is evidence that red blood cells move out of the spleen during splenectomy. These have been treated with spleen. Red blood cells return to the blood circulation, and this part of the cell population can be detected by osmotic fragility. After splenectomy, these red blood cell populations disappear, and early by simulating spleen conditions (including low pH, isolated red blood cells can be in contact with the reticuloendothelial system, etc.) In vitro culture studies of HS erythrocytes showed that the lack of sugar and the lack of intracellular ATP were not the cause of HS erythrocyte destruction in the spleen. The effect of spleen conditions showed cumulative damage, and the average time of HS red blood cells staying in the spleen cord For 10 to 100 minutes, only 1% to 10% of the blood flowing through the spleen is temporarily retained in the spleen and filled with spleen, and the remaining 90% of the blood rapidly flows into the venous circulation. Although HS red blood cells are mainly detained and destroyed in the spleen, HS cells are also In other peripheral organs, the surface of the HS red blood cell changes triggers the phagocytosis of the reticuloendothelial system. The system is still unclear. One pathway may be the destruction of phospholipids in the lipid bilayer structure, leading to the lateral exposure of phosphatidylserine, promoting the attachment of red blood cells to the reticuloendothelial system, causing destruction of other organs outside the spleen, although phospholipids The distribution in the two lipid bilayers is normal in most HS patients, but there are abnormal changes in the distribution of phospholipids in some patients with severe HS. There is also a hypothesis that the terminal HS red blood cells treated with spleen have no phospholipids. Uniform occurrence.
2. Molecular mechanism
The membrane of normal red blood cells is an asymmetric phospholipid bilayer structure with non-esterified cholesterol and glycolipid insertion. The outer layer of the membrane is choline phospholipid (phosphatidylcholine also called lecithin and sphingomyelin), and the inner layer is amino acid phospholipid. (phosphatidylaminoethanol and phosphatidylserine), the erythrocyte membrane also contains asymmetric protein components, all glycoproteins are exposed to the outer surface of the membrane, with red blood cell antigens and receptors or transporters, the overall membrane protein penetration or Crossing the lipid bilayer, interacting with the core of the hydrophobic lipid and tightly binding the erythrocyte membrane, an independent protein network forms a vertical and horizontal interaction with the integral membrane protein and lipid bilayer, the membrane skeleton including The spectrin (or contractile protein, which is further divided into and spectrin), ankyrin (inkyrin), protein 4.1, protein 4.2 and actin, HS are classified into the following five subtypes: single spectrin partial deficiency The lack of a link between the spectrin and the ankyrin, the lack of a 3 part, the lack of protein 4.2 and other common lacks.
(1) Partial spectrin partial deficiency: single spectrin partial deficiency including -spectrin and -spectrin, a large number of literatures have confirmed -spectrin in patients with dominant genetic HS lacking spectrin deficiency Gene (SPTB) mutations exist, with one exception, the beta-spectrin Houston has been shown to be a frameshift mutation in some families, these mutations are localized, are distinct individual families, and may be associated with beta-spectrin Related to the accumulation of reduced mRNA, -spectrin Kissimmee is a point mutation in a highly conserved region of -spectrin localized to interact with protein 4.1, a restricted protein 4.1 and spectrin to actin The dysfunction of the linkages, therefore, enhances its limiting function by treating the red blood cells in the circulation by reducing agents. These red blood cells are rich in reduced glutathione, and the reduction of spectrin/protein 4.1 is a non-functional expression, single blood. In patients with non-dominant genetic HS, which lacks image protein, is a deficiency of -spectrin. In normal red blood cells, the amount of -spectrin synthesis is much higher than that of -spectrin, -spectrin gene (SPTA1). Variants lead to reduced - spectrin protein synthesis, since the - - spectrin than spectrin protein synthesis.
Thus, there is a normal amount of spectrin heterodimer combination in the membrane, therefore, a normal alpha-spectrin and a defective alpha-spectrin allele can be asymptomatic, pure The zygote or complex heterozygous -spectrin deficiency HS individuals will be severe HS patients, Wichterle et al. reported a case of heterozygous -spectrin deficiency in severe HS cases with two different - The spectrin gene is deficient, and there is a splicing deletion associated with the upstream intervening sequence mutation (LEPRA) on one allele; another gene mutation in the other allele, ie aPRAGUE, LEPRA allele Produces a 6-fold less corrected serotype alpha spectrin transcript than the normal allele, and further studies have shown that many non-dominant spectrins lack HS, LEPRA and Bug Hill (in the II domain) The linkage of an amino acid-substituted domain is unbalanced, so the alpha-LEPRA allele is associated with other alpha-contractor-deficient heterozygous individuals, resulting in a marked globulin-deficient globular erythrocyte increase. Hemolytic hemolytic anemia, using pulse-labeled BFU-E studies, showed that alpha-spectrin synthesis in some lethal or near-fatal HSs with severe spectrin deficiency (about 26% of normal components) Significantly reduced, although the molecular basis of these defects is unclear, there are mothers with a mildly dominant HS and a family history of a father with a slight increase in osmotic fragility and normal hematology, suggesting at least two genetic defects The possibility of simple heterozygotes.
(2) Lack of binding of spectrin to ankyrin: The biochemical manifestation of the lack of binding between spectrin and ankyrin was first proposed by Coetzer et al in 1988, and anchor protein represents the major junction of spectrin on the membrane. Therefore, although the synthesis of spectrin is normal, it is not surprising that ankyrin deficiency is accompanied by a corresponding proportion of spectrin reduction. For example, beta-spectrin mutant HS, most ankyrin defects belong to mRNA accumulation. Reduction of related point mutations, except for the ankyrin Florisnopolis, which is associated with severe HS, as evidenced by HS patients from three different genetic background families, 15% to 20% of the ankyrins reported in the current report The gene (ANK1) mutation is a de novo mutation, and a parental mosaic ankyrin mutation is found in two families. Therefore, there are cases with different clinical symptoms in the same HS family, including the deletion of the ankyrin gene. Or atypical HS cases with displaced karyotypic abnormalities have also been reported. In one patient, deletion of all ankyrin genes on chromosome 8 resulted in a large gap deletion, anchor White deletion may be typical symptoms spherocytosis, mental retardation, and a portion of a typical face adjacent to the gene to reduce gonadal function syndrome.
(3) Partial deficiency of band 3 protein: lack of 3 protein parts found in patients with light, moderately dominant HS, accompanied by mushroom-like or pincer-shaped red blood cells, most of which are associated with protein 4.2 deficiency, so far, found Nearly 50 different band 3 mutations are associated with HS. These mutations extend throughout band 3, in the cytoplasmic region and membrane cleavage region, and homozygous with 3 mutations (with 3Coimbra) can cause lethal or near-lethal HS With fetal edema, metabolic acidosis, and severe anemia associated with a complete absence of 3 and a lack of protein 4.2, the allele that affects the 3 protein (SLC4A1) has been identified, and when the 3 protein mutation is continuously inherited, it will be aggravated. Band 3 deficiency and worsening the clinical symptoms of the disease, some cases with 3 lack of HS, reticulocytes decreased, this case with 3 synthesis and mRNA levels are normal, but also found in some cases with 3 protein Stabilization, the mechanism that causes the deletion of band 3 is unclear. The mechanism of hypothesis is: weakening the connection between band 3 protein and ankyrin, resulting in the lack of initial band 3 protein or ankyrin; or lacking a "part" with a combination of 3 on the membrane. Some bands 3 patients with HS deficiency, band 3 gene expression can be reduced, or a band 3 mutation can interfere with the intrinsic joint transcriptional insertion of band 3 into the endoplasmic reticulum membrane, or hinder the translocation of band 3 to the protoplast membrane, and some with 3 mutation clusters The sorbitol fatty acid ester (span) region of the membrane, the sorbitan fatty acid ester (span) region of these membranes replaces a wide range of conserved arginine, all of which are localized to the cytoplasmic transmembrane helix At the end, the direction of the transmembrane sorbitol fatty acid ester fragment was maintained. It is speculated that this phenomenon may be that the mutant band 3 is not folded after synthesis, inserted into the endoplasmic reticulum, and DS-PAGE is used to study the fast-moving band 3 and found to have 3 sugars. Defects in post-translational translation, as well as more rapid migration of glycophorin A, are involved in band 3 glycosylation, and its precise molecular defects and role in the pathogenesis of these patients are unclear.
(4) Protein 4.2 deficiency: In Japan, the recessive genetic HS of the protein 4.2 gene (EPB42) mutation is very common. These cases tend to be homozygous. The protein 4.2 of their erythrocyte membrane is almost completely deleted, and the red blood cells lacking protein 4.2 can also be used. There is a lack of ankyrin and band 3 protein, and a few reports have shown that protein 4.2 lacks the linkage of protein 4.2 to membrane due to changes in the band 3 cytoplasmic region. These changes include speculative sites of protein 4.2 and band 3. It has been reported in the literature that in two patients with complex homozygous HS with a lack of 3, the erythrocyte membrane has a partial band 3 deficiency and a total protein 4.2 deficiency, since other mutant bands 3 (with 3Fukuoka) contain a band 3-protein 4.2 interaction. Mutation of the region, speculating that a mutant band 3 protein (with 3Okinawqa), linking all available proteins 4.2 on erythroid progenitor cells, due to the inability of 3Okinawqa to insert into the erythrocyte membrane, the 3Okinawqa-protein 4.2 complex is degraded, causing the above Phenotype.
3. The molecular basis of the lack of surface area
The intrinsic properties of hereditary spheroidal red blood cells are unstable, such as the release of lipids in the absence of adenosine triphosphate (ATP) or cell-induced emergency shear exposure, and the loss of membrane material through 0.2-0.5 m of spectrin-containing protein. The release of small vesicles in the membrane of the membrane, which can be confirmed by the increase in osmotic fragility in vitro culture experiments, the loss of membrane material is the result of the lack of a certain surface area of the membrane, in the absence of single spectrin or spectrin and anchor In the case of protein-deficient defects, the surface region lacks a lipid bilayer membrane that is not matched under the cytoskeletal protein. The skeletal protein of normal red blood cells forms a sub-membrane layer close to a single molecule, occupying more than half of the membrane surface. Therefore, spectrin The lack of this network reduces the density of the network. As a result, the skeletal protein released from the microvesicles in the cell does not directly support the region of the lipid bilayer membrane. In the case of HS with 3 protein deficiency, two hypothetical pathways may lead to surface regions. Loss (Figure 2), a mechanism consisting of band 3 protein loss from the cell, due to many times the band 3 protein spans the lipid bilayer membrane, The substantial amount of "boundary" lipids is released together with the band 3 protein, thus resulting in a lack of surface areas. Another possible mechanism is the formation of a zone in the membrane without strips 3, which in turn forms a large bubble of the membrane. The form of vesicles is released from the cell. This hypothesis is based on the discovery that the clustering of the particles in the residual image of the cell membrane (the main component of the band 3 protein) leads to the formation of membrane lipid vesicles rather than microparticles. Evidence comes from a model with a knockout mouse that lacks red blood cells with 3 instinctively detaches vesicles, resulting in severe spherocytosis and hemolysis.
4.HS and non-red clinical manifestations
In most HS cases, clinical manifestations are limited to a single erythroid system, possibly due to non-red copies of erythrocyte membrane proteins (such as spectrin and cytoskeletal proteins) being encoded by independent genes or by certain proteins (eg, protein 4.1, --spectrin and cytoskeletal proteins are subordinate to tissue-specific selective splicing, but there are exceptions, reporting that individual HS families have combined neuronal segregation or muscle abnormalities of spinal degeneration, cardiomyopathy or memory loss, erythrocyte cytoskeletal proteins and Beta-spectrin is also present in muscle brain tissue and spinal cord, increasing the likelihood that these cases lack one of these proteins. This hypothesis will be further confirmed by the HS model of nb mutant mice, homozygous nb/nb mice have The serious HS associated with the lack of spectrin and the basic molecular defect skeletal protein, the progression of the disease can become a neurological syndrome consistent with the degeneration of cerebellum Purkinje cells, Purkinje cells usually express erythrocyte cytoskeletal protein, and the expression in nb/nb mice is Reduced, band 3 deficiency is also confirmed in patients with autosomal dominant distal renal tubular acidosis, miscellaneous Cases with subband 3 gene mutations have normal renal acidification and abnormal red blood cells, and two bands with 3 mutations, namely R589H and S613F, are associated with decreased acidification of the kidney and normal red blood cells, and have been reported to be due to mutations in the band 3 mRNA processing. Two cases of Hs family with attenuated renal acidification, with 3Pribram and 3Okinawqa, in these cases, the exact pathogenesis of renal tubular acidosis remains unclear.
5. Hereditary
Based on the non-unitary molecular basis of HS, it is speculated that the HS gene can be divided into several chromosome changes. Currently, the chromosomal abnormalities found are abnormalities of 1, 8, 14, 15 and 17, and -spectrin is related to 1 Chromosome, chromosome 8 is associated with ankyrin, chromosome 14 is associated with -spectrin, chromosome 17 is associated with protein 3, and chromosome 15 is associated with protein 4.2. HS patients (about 75%), are autosomal dominant, a small number of patients are non-dominant inheritance, this part of the case can be attributed to genetic mutations, the location of the mutation in the CpG dinucleotide, resulting in a small deletion in the site Or insertion, which may also form autosomal recessive inheritance. It has been reported that some patients with partial recessive HS are associated with severe hemolytic anemia. These patients are mainly inclined to the lack of erythrocyte spectrin, which is mainly - The lack of spectrin, another part of recessive hereditary patients with protein 4.2 deficiency, manifested as mild hemolysis, red blood cell morphology is oral and oval, very few cases are homozygous, showing severe hemolytic anemia Some patients may be fatal after hemolysis, and their symptoms are mild or asymptomatic parents, HS can onset in the form of family, but such cases are rare clinically, these phenomena can be explained by the following points:
1 lack of variable penetrance.
2 Newborn mutations or recessive inheritance occur in the family.
3 Modification of alleles affecting membrane protein expression results in variability in clinical manifestations in the family.
4 lack of tissue-specific mosaic type.
Prevention
Pediatric hereditary spherocytosis prevention
The disease is an autosomal dominant hereditary disease, the preventive measures are the same as hereditary diseases, and the prevention should be from pre-pregnancy to prenatal.
1. Premarital medical examination: Premarital examination items and contents mainly include serological examination (such as hepatitis B virus, treponema pallidum, HIV), reproductive system examination (such as screening for cervical inflammation), general physical examination (such as blood pressure, electrocardiogram), and inquiry of disease family. History, personal medical history, etc., do a good job in genetic disease counseling. Premarital medical examination plays a positive role in preventing birth defects.
2. Pregnant women should avoid harmful factors as much as possible, including away from smoke, alcohol, drugs, radiation, pesticides, noise, volatile harmful gases, toxic and harmful heavy metals.
Complication
Pediatric hereditary spherocytosis complications Complications gallstones
Anemia can occur at any stage of the disease:
1. Hemolytic crisis: The most common, mild symptoms, often no significant clinical significance, the course of the disease is self-limiting, generally secondary to a variety of infections caused by mononuclear macrophage system function transiently enhanced.
2. Aplastic crisis: rare, severe symptoms, can be life-threatening, often need blood transfusion, clinical features of low bone marrow erythroid hyperplasia, reticulocyte count decreased, the crisis is generally caused by parvovirus B19 infection, parvovirus B19 It can invade erythroid progenitor cells and inhibit its proliferation and differentiation. The signs of parvovirus B19 infection are influenza-like syndrome and cheek flushing syndrome (expressed as red maculopapular rash on the face, trunk and limbs).
3. Giant cell anemia crisis: When the supply of folic acid in the diet is insufficient or the body's demand for folic acid is increased, such as repeated hemolysis, pregnancy, etc. without timely supplementation, megaloblastic anemia may occur.
4. Gallbladder stones: More than half of HS suffer from bilirubin gallstone disease, the highest incidence rate is 10 to 30 years old (55% to 75%). The incidence rate after 30 years old is the same as that of the general population, and the incidence of children under 10 years old The rate is less than 5% and the youngest patient is only 3 years old.
Symptom
Pediatric hereditary spherocytosis symptoms common symptoms erythrocytosis jaundice hepatosplenomegaly hemolytic anemia all organs of the blood flow slow
The clinical manifestations are significantly heterogeneous. The age of onset and the severity of the disease vary greatly. HS is more common in children or children, from asymptomatic to life-threatening anemia, and severe in neonatal or infancy. Beijing Children's Hospital Among the 170 cases, 139 cases occurred within 5 years old, accounting for 82%, and half of them were within 1 year old. The clinical manifestations of different families may vary greatly. Different patients in the same family often have the same severity. According to clinical manifestations, HS can be divided into 4 types: asymptomatic carriers, light HS, typical HS and heavy HS, most of the children are dominantly inherited, the clinical manifestations are mild to moderate anemia; very few children are recessive Genetic homozygous or alleles are mutated, clinical manifestations of severe HS, anemia, jaundice and hepatosplenomegaly are the most common clinical manifestations of HS, three or coexist, or occur alone, Beijing Children's Hospital admitted 170 In HS, 169 cases (99%) of anemia, 133 cases (78%) of jaundice, 155 cases (91%) of liver, and 168 cases (99%) of splenomegaly constitute the four major manifestations of this disease. Most HSs have Mild to moderate anemia, moderate splenomegaly and intermittent jaundice, a few ( 25%) HS mild symptoms, although there hemolysis, but because of bone marrow compensatory erythroid hyperplasia.
Generally no anemia, no or only mild jaundice, no or mild splenomegaly, these patients are only discovered when a family survey or a certain cause causes red blood cell damage to be aggravated, the most common cause is infection, strenuous physical strength Activities can also aggravate hemolysis, very few HS can occur life-threatening hemolysis, need regular blood transfusion, growth and development can also be affected, long-term anemia, due to bone marrow hyperplasia, bone marrow cavity widened, the frontal bone and tibia protruding, newborn The onset of the disease, the incidence of jaundice is about 50%, often occurs within 48 hours after birth, and bilirubin encephalopathy can occur due to hyperbilirubinemia. After the neonatal period, jaundice is mostly light and intermittent. Attacks, fatigue, and infection can induce or aggravate jaundice.
Examine
Examination of pediatric hereditary spherocytosis
Blood picture
Mild, moderate or severe anemia can occur without anemia. Reticulocytes increased by 5% to 20%, the lowest 2%, and also higher than 20%. The number of white blood cells is normal or slightly increased, and may increase in the case of hemolytic crisis. The number of platelets is normal. In the case of aplastic crisis, anemia is aggravated, and even whole blood cells are reduced, and reticulocytes are also reduced. Red blood cell morphology: small spheroidal red blood cells can be seen by microscopic examination of blood smear (Fig. 3). The number of these cells varies, generally accounting for 20% to 30% of red blood cells, and only 1% to 2%. It is characterized by a small cell diameter (6.2 to 7.01 m) and an increased thickness of 2.2 to 3.4 m (normally 1.9 to 2.0 m), and the cell body is small and stained deeply, without a centrally lightly stained area and a double concave disk shape. Small spherical red blood cells are limited to mature red blood cells, and nucleated red blood cells and reticulocytes are normal in morphology. In heavy HS, blood smears can be seen in addition to a large number of small spherical red blood cells, as well as many spinous red blood cells. The MCV is only slightly reduced and the MCHC is increased.
2. Red blood cell morphology
Blood smears can be seen in small spherical red blood cells. The number of these cells varies, generally accounting for 20% to 30% of red blood cells, and only 1% to 2%. It is characterized by small cell diameter (6.2~7.0m) and thickness increase of 2.2~3.4m (normally 1.9~2.0m), small cell body and deep staining, no central light-stained area and double concave disk shape. Small spherical red blood cells are limited to mature red blood cells, and nucleated red blood cells and reticulocytes are normal in morphology. In heavy HS, blood smears can be seen in addition to a large number of small spherical red blood cells, as well as many spinous red blood cells.
3. Bone marrow
Proliferation is mainly due to the proliferation of middle and late erythrocytes. Poor hyperplasia in aplastic anemia, visible huge early red blood cells, splenectomy is a safe and effective method for the treatment of pediatric hereditary spherocytosis. The age of surgery is appropriate for age-age. Premature spleen may affect the body's immune function and is prone to serious infections. However, if the anemia is severe, affecting the growth and development of the child, or the "disaster crisis" often occurs. Consider an earlier surgery. After splenectomy, the increase of jaundice and reticulocytes can quickly disappear, the blood redness can reach the normal range, and the formation of gallstones can be prevented, and the threat of regeneration crisis can be eradicated, but the increase of spherical red blood cells can make the red blood cells penetrate and fragile. The increase is more obvious. When there is a possibility of infection such as fever after surgery, it should be treated with antibiotics in time.
4. Red blood cell osmotic fragility test
It is the main method to diagnose this disease. In most cases, the erythrocyte osmotic fragility is increased, and the degree of increase is proportional to the number of spherical cells. In the case of a small number of spherical red blood cells, the red blood cell osmotic fragility test can also be normal, and the red blood cells must be incubated at 37 ° C for 24 h before the osmotic fragility is increased. The mechanical fragility of red blood cells is increased. When the aplastic crisis and the combined iron deficiency, the erythrocyte osmotic fragility can be reduced accordingly.
5. Red blood cell autolysis and autolysis test
The hemolytic degree of 48h is obviously increased, which can reach 10% to 50% (normal 5%). The addition of glucose or ATP may not be completely corrected.
6. Acidified glycerol dissolution test (AGLT50)
The normal human red blood cell AGLT50 is about 1800s, and the severe HS patient AGLT50 can be within 150s. The method is simple to operate and is suitable for diagnosis and screening.
7. erythrocyte membrane protein qualitative analysis
Qualitative analysis of membrane proteins can be performed by SDS-PAGE. More than 80% of HSs can be found abnormal, and immunoblotting can improve the credibility. Quantitative analysis of membrane proteins of each erythrocyte can also be performed directly by radioimmunoassay or ELISA.
8. Other
The serum did not bind to bilirubin, the urinary biliary was normal or increased, and the faecal biliary was increased. The 51Cr label measures the shortened life of red blood cells and has a half-life (T1/2) of 8 to 18 days. Serum haptoglobin decreased and lactate dehydrogenase increased. The Coombs test was negative. Serum folate levels are generally reduced.
Routine imaging examination, such as chest X-ray, B-ultrasound, pay attention to the presence or absence of lung infections, gallstones and hepatosplenomegaly.
Diagnosis
Diagnosis and differential diagnosis of pediatric hereditary spherocytosis
diagnosis
Typical cases can be diagnosed according to jaundice, anemia, splenomegaly, spherocytosis, reticulocyte increase, erythrocyte fragility and positive family history. Light cases, especially spherical red blood cells, and osmotic fragility, must be After the red blood cell incubation, the fragility test and the autologous hemolysis test can be diagnosed. The diagnosis of a small number of HSs depends on the analysis or measurement of erythrocyte membrane proteins. For splenomegaly and cholelithiasis, which are unknown to adolescents, infection, especially parvovirus B19 infection, is contagious. In the case of unexplained hemolytic anemia in mononucleosis, HS should be suspected and further examination is needed.
Differential diagnosis
1. Autoimmune hemolytic anemia (AIHA): This disease has hemolysis symptoms, increased spherocytosis and increased osmotic fragility, but no family history. Positive anti-human globulin test is an important basis for the diagnosis of this disease. In general, HS The morphology of small spherical red blood cells in peripheral blood is relatively uniform, while the size of spherical red blood cells in peripheral blood of other hemolytic diseases is different. It is difficult to distinguish with HS by multiple negative AIHA Coombs test. MCHC measurement, red blood cell osmotic fragility test and autolysis test have Help identification, but when the AIHA spherical red blood cells are more, the red blood cell osmotic fragility test can also be positive. Although the erythrocyte membrane protein analysis or component quantification has certain discriminative significance, it is not unique to HS.
2. Drug-induced immune hemolytic anemia: Spherical cells may also appear, and the erythrocyte osmotic fragility is increased, but there is a clear history of medication, anti-human globulin test is positive, and hemolysis subsides after stopping the drug.
3. Neonatal hemolysis: Peripheral blood may be confused with hereditary spherocytosis due to the temporary appearance of spherical red blood cells, but the former mother and child ABO and Rh blood types are different, anti-human globulin test is positive, which is helpful for identification.
4. Others: G-6-PD deficiency, unstable hemoglobin disease (including HbH) and Rhemia deficiency caused by hemolytic anemia can have a few spherical cells, but G-6-PD deficiency anemia is often offensive More can find the cause, for genetic association, red blood cell G-6-PD reduction, unstable hemoglobin disease heat instability test and globin small body production test positive, hemoglobin electrophoresis can be diagnosed, Rh deficiency is extremely rare, peripheral blood A large number of oral red blood cells and a small number of spherical red blood cells can be seen, and the Rh antigen is partially or completely absent.
