Delay in the measurement of eosin-5′-maleimide (EMA) binding does not affect the test result for the diagnosis of hereditary spherocytosis

A large family of hereditary spherocytosis and a rare case of hereditary elliptocytosis with a novel SPTA1 mutation underdiagnosed in Taiwan: A case report and literature review

RATIONALE

Hereditary spherocytosis (HS) has a defect in the vertically connected proteins on the cell membrane of red blood cells (RBC). Hereditary elliptocytosis (HE) has a defect in proteins that connect the cell membrane horizontally. We reported two families of RBC membrane disorders in Taiwanese, one was HS and the other was HE.

PATIENT CONCERNS

Case 1. A 19-year-old male student with chronic jaundice and splenomegaly. His mother, maternal uncle, grandmother, and many members of older generations also had splenomegaly and underwent splenectomy. Case 2. A 40-year-old man has experienced pallor and jaundice since the age of 20 and was found to have splenomegaly, and gall bladder stones in the older age. His younger sister also had pallor and jaundice for a long time.

DIAGNOSES

In case 1, a peripheral blood smear showed 20% spherocytes. Eosin-5-maleimide labeled RBC by flow cytometry showed a result of 30.6 MCF (cutoff value: 45.5 MCF). He was diagnosed with HS. The gene analysis identified a heterozygous mutation with c.166A > G (p.Lys56Glu) in the SLC4A1 gene in this proband, his mother, and maternal uncle. In case 2, more than 40% of ellipsoid RBC present in the peripheral blood smear. He was diagnosed with HE. Genetic analysis of the SPTA1 gene identified a novel heterozygous exon2, c.86A > C, p.Gln29Prol mutation.

INTERVENTIONS

The two patients had compensated anemia, clinical follow-up instead of splenectomy was done.

OUTCOMES

The two patients had normal daily activities and lives.

LESSONS

We reported two Taiwanese families, one was hereditary spherocytosis affected by a heterozygous mutation with c.166A > G (p.Lys56Glu) in SLC4A1, and the other was hereditary elliptocytosis caused by a novel heterozygous SPTA1 gene mutation, c. 86A > C, p.Gln29Prol. These 2 seemingly common hereditary red blood cell membrane protein defects induced by hemolysis are usually underdiagnosed or misdiagnosed.

Flow Cytometric Test with Eosin-5-Maleimide for a Diagnosis of Hereditary Spherocytosis in a Newborn

A term male newborn born to a mother who had hereditary spherocytosis presented with neonatal jaundice at 20 hours of life. Complete blood count showed hemoglobin 17.1 g/dL, MCV 104.2 fL, MCH 32.9 pg, and MCHC 31.6 g/dL. The patient had indirect hyperbilirubinemia requiring phototherapy. The maximum total bilirubin level was 12.15 mg/dL at 20 hours of life. Peripheral blood smear revealed spherocytes, crenated red cells, and polychromasia. A flow cytometric test with eosin-5-maleimide- (EMA-) labeled RBC was performed in the patient and parents. The fluorescence histograms of EMA-labeled RBC from the patient and mother were shifted to the left, and the fluorescence ratio when compared with normal was 0.69 and 0.84, respectively. The flow cytometric test with EMA is useful in supporting the diagnosis of hereditary spherocytosis during newborn period.

Old and new insights into the diagnosis of hereditary spherocytosis

Hereditary spherocytosis (HS) belongs to the group of congenital hemolytic anemias resulting from plasma membrane protein deficiency. When diagnosed too late, HS bares the risk of long-term complications including gall stones and severe anemia. Here, there are discussed advances in HS screening and diagnostics, with a particular focus on methodologies, most of which are available in clinical laboratories worldwide.

Delayed Measurement of Eosin-5'-Maleimide Binding May Affect the Test Results of Highly Hemolyzed Samples In Vivo and In Vitro-A Case Study

Diagnosis of hereditary spherocytosis (HS) is based on clinical evaluation and eosin-5'-maleimide (EMA) test. A decrease in EMA fluorescence compared with healthy individuals is typical for HS and serves as a basis for HS diagnosis. Sensitivity and specificity of the test is high and false-positive results rarely occur. Studies have shown that anticoagulated blood sample when stored at 4°C for 7 days do not affect the test results. This case study is about an autoimmune hemolytic anemia patient who showed a primary positive result for EMA test (decrease in EMA fluorescence-47% compared with 100% for samples of healthy individual), when the test was performed in the sample stored for 48 hours after venipuncture and before staining. An irrelevant decrease (92.5% compared with 100% for samples of healthy individual) was found when freshly collected sample was analyzed. On the basis of the results obtained, it is recommended that EMA staining should be performed on the same day of blood collection for patients with significant hemolysis.

Flow cytometry in hematological nonmalignant disorders

Multiparameter flow cytometry (MFC) has become an integral part of the diagnosis and classification of hematological malignancies. However, several nonmalignant or premalignant disorders may benefit from this technology in hematology laboratories. This review provides information on the normal immunophenotypic characteristics of peripheral blood leukocyte subsets and their modifications in several clinical conditions. The usefulness of MFC and the specific markers that can be investigated in hyperlymphocytosis, infection, hypereosinophilia, paroxysmal nocturnal hemoglobinuria, and large granular lymphocyte disorders is described. Mention is also made of the developments of MFC for analyses of red blood cells or platelets.

Evaluating eosin-5-maleimide binding as a diagnostic test for hereditary spherocytosis in newborn infants

OBJECTIVE

Neonates with undiagnosed hereditary spherocytosis (HS) are at risk for developing hazardous hyperbilirubinemia and anemia. Making an early diagnosis of HS in a neonate can prompt anticipatory guidance to prevent these adverse outcomes. A recent comparison study showed that a relatively new diagnostic test for HS, eosin-5-maleimide (EMA)-flow cytometry, performs better than other available tests in confirming HS. However, reports have not specifically examined the performance of this test among neonates.

STUDY DESIGN

We compared EMA-flow cytometry from blood samples of healthy control neonates vs samples from neonates suspected of having HS on the basis of severe Coombs-negative jaundice and spherocytes on blood film. The diagnosis of HS was later either confirmed or excluded based on clinical findings and next generation sequencing (NGS) after which we correlated the EMA-flow results with the diagnosis.

RESULT

EMA-flow was performed on the blood of 31 neonates; 20 healthy term newborns and 11 who were suspected of having HS. Eight of the 11 were later confirmed positive for HS and one was confirmed positive for hereditary elliptocytosis (HE). All nine had persistently abnormal erythroid morphology, reticulocytosis and anemia, and eight of the nine had relevant mutations discovered using NGS. The other was confirmed positive for HS on the basis that a parent had HS, and the neonate's spherocytosis, reticulocytosis and anemia persisted. The 20 healthy controls and the 2 in whom HS was initially suspected but later excluded all had EMA-flow results in the range reported in healthy children and adults. In contrast, all nine in whom HS or HE was confirmed had abnormal EMA-flow results consistent with previous reports in older children and adults with HS.

CONCLUSION

Although our sample size is small, our findings are consistent with the literature in older children and adults suggesting that EMA-flow cytometric testing performs well in supporting the diagnosis of HS/HE during the early neonatal period.

Mean corpuscular volume of control red blood cells determines the interpretation of eosin-5'-maleimide (EMA) test result in infants aged less than 6 months

Eosin-5′-maleimide (EMA) binding test is a flow cytometric test used to detect hereditary spherocytosis (HS). To perform the test sample from patients, 5–6 reference samples of red blood are needed. Our aim was to investigate how the mean corpuscular volume (MCV) of red blood cells influences on the value of fluorescence of bounded EMA dye and how the choice of reference samples affects the test result. EMA test was performed in peripheral blood from 404 individuals, including 31 children suffering from HS. Mean fluorescence channel of EMA-RBCs was measured with Cytomics FC500 flow cytometer. Mean corpuscular volume of RBCs was assessed with LH750 Beckman Coulter. Statistical analysis was performed using Graph Pad Prism. The correlation Spearman coefficient between mean channel of fluorescence of EMA-RBCs and MCV was r = 0.39, p < 0.0001. Interpretation of EMA test depends on MCV of the reference samples. If reference blood samples have lower MCV than the patients MCV, EMA test result might be negative. Due to different MCV values of RBCs in infancy and ca. Three months later, EMA test in neonates might be interpreted falsely negative. Samples from children younger than 3 months old had EMA test result 86.1 ± 11.7 %, whereas same samples that analyzed 4.1 ± 2.1 later had results of 75.4 ± 4.5 %, p < 0.05. Mean fluorescence of EMA-bound RBC depends on RBC’s volume. MCV of reference samples affects EMA test results; thus, we recommend selection of reference samples with MCV in range of ±2 fL compared to MCV of patient RBC’s.