Molecular diagnostic update in hereditary hemolytic anemia and neonatal hyperbilirubinemia

Developing and evaluating a predictive model for neonatal hyperbilirubinemia based on UGT1A1 gene polymorphism and clinical risk factors

Background

Neonatal hyperbilirubinemia (NHB) is one of the most common diseases in the neonatal period. Without timely diagnosis and treatment, it can lead to long-term complications. In severe cases, it may even result in fatality. The UGT1A1 gene and clinical risk factors play important roles in the development and progression of NHB.

Methods

In this study, we conducted a cohort study and analyzed 3258 newborns from the Jilin Women And Children Health Hospital in northern China, including 372 children with hyperbilirubinemia. We established a predictive model using a logistic regression model based on clinical risk factors and the polymorphism of the G211A locus in the UGT1A1 gene of newborns. Furthermore, the performance of the prediction model was evaluated using the ROC curve.

Results

The logistic regression model indicates that the following factors are associated with an increased risk of NHB: the time when stool turns yellow [P ≤ 0.001, OR 1.266 (95% CI: 1.125-1.425)]; neonatal cephalohematoma [P ≤ 0.001, OR 33.642 (95% CI: 21.823-51.861)]; hemolytic disease of newborn [P ≤ 0.001, OR 33.849 (95% CI: 18.589-61.636)]; neonatal weight loss [P ≤ 0.001, OR 11.275 (95% CI: 7.842-16.209)]; neonatal premature rupture of membranes (PROM) history [P = 0.021, OR 1.422 (95% CI: 1.056-1.917)]; genetic polymorphism at the UGT1A1 gene G211A locus. Gestational age is a protective factor [P ≤ 0.001, OR 0.766 (95% CI: 0.686-0.855)]. Compared to natural labor, cesarean section is a protective factor [P = 0.011, OR 0.711 (95% CI: 0.546-0.926)], while assisted delivery is a risk factor [P = 0.022, OR 2.207 (95% CI: 1.121-4.346)]. The area under the curve (AUC) of this prediction model is 0.804 (95% CI: 0.777-0.831), indicating good discrimination ability and value for predicting the risk of NHB after birth.

Conclusion

We have developed and evaluated a predictive model that combines UGT1A1 gene polymorphism and clinical risk factors for the first time. By using this nomogram and taking into account the results of serum total bilirubin measurement or transcutaneous bilirubin measurement, early prediction of the risk of neonatal hyperbilirubinemia can be achieved.

Hereditary Spherocytosis: Can Next-Generation Sequencing of the Five Most Frequently Affected Genes Replace Time-Consuming Functional Investigations?

Congenital defects of the erythrocyte membrane are common in northern Europe and all over the world. The resulting diseases, for example, hereditary spherocytosis (HS), are often underdiagnosed, partly due to their sometimes mild and asymptomatic courses. In addition to a broad clinical spectrum, this is also due to the occasionally complex diagnostics that are not available to every patient. To test whether next-generation sequencing (NGS) could replace time-consuming spherocytosis-specific functional tests, 22 consecutive patients with suspected red cell membranopathy underwent functional blood tests. We were able to identify the causative genetic defect in all patients with suspected HS who underwent genetic testing (n = 17). The sensitivity of the NGS approach, which tests five genes (ANK1 (gene product: ankyrin1), EPB42 (erythrocyte membrane protein band4.2), SLC4A1 (band3), SPTA1 (α-spectrin), and SPTB (β-spectrin)), was 100% (95% confidence interval: 81.5-100.0%). The major advantage of genetic testing in the paediatric setting is the small amount of blood required (<200 µL), and compared to functional assays, sample stability is not an issue. The combination of medical history, basic laboratory parameters, and an NGS panel with five genes is sufficient for diagnosis in most cases. Only in rare cases, a more comprehensive functional screening is required.

Coagulation profile of neonates with hyperbilirubinaemia in full-term newborns

OBJECTIVE

To determine the relationship between coagulation system markers and hyperbilirubinaemia in full-term neonates.

METHODS

This retrospective case-control study enrolled full-term neonates with hyperbilirubinaemia and healthy control full-term neonates. Prothrombin time (PT), thrombin time (TT), fibrinogen (Fbg), activated partial thromboplastin time (APTT) and international normalized ratio (INR) were recorded. The correlation between INR and total bilirubin and between INR and indirect bilirubin was analysed by linear regression analysis. Receiver operating characteristic curve analysis was used to assess the efficacy of INR to identify neonates with hyperbilirubinaemia.

RESULTS

This study enrolled 40 full-term neonates with hyperbilirubinaemia and 30 healthy controls. PT, INR and APTT were significantly higher in the neonates with hyperbilirubinaemia compared with the healthy controls. There was a significant positive correlation between INR and the level of total bilirubin in neonates with hyperbilirubinaemia (R = 0.3327). There was also a significant positive correlation between INR and the level of indirect bilirubin in neonates with hyperbilirubinaemia (R = 0.3406). INR in neonates with hyperbilirubinaemia significantly achieved an area under the curve of 0.800 (95% confidence interval, 0.6288, 0.9712; cut-off value, 1.060; specificity, 71.43%; sensitivity, 80.00%).

CONCLUSION

These findings suggest that INR is a novel biomarker for the diagnosis of neonatal hyperbilirubinaemia in full-term neonates.

Variant spectrum of PIEZO1 and KCNN4 in Japanese patients with dehydrated hereditary stomatocytosis

Hereditary stomatocytosis (HSt) is a type of congenital hemolytic anemia caused by abnormally increased cation permeability of erythrocyte membranes. Dehydrated HSt (DHSt) is the most common subtype of HSt and is diagnosed based on clinical and laboratory findings related to erythrocytes. PIEZO1 and KCNN4 have been recognized as causative genes, and many related variants have been reported. We analyzed the genomic background of 23 patients from 20 Japanese families suspected of having DHSt using a target capture sequence and identified pathogenic/likely pathogenic variants of PIEZO1 or KCNN4 in 12 families.

Clinical utility of targeted next-generation sequencing panel in routine diagnosis of hereditary hemolytic anemia: A national reference laboratory experience

INTRODUCTION

Hereditary hemolytic anemias (HHA) comprise a heterogeneous group of disorders resulting from defective red blood cell (RBC) cytoskeleton, RBC enzyme deficiencies, and hemoglobin (Hb) synthesis disorders such as thalassemia or sideroblastic anemia.

MATERIALS AND METHODS

Our hemolytic anemia diagnostic next-generation sequencing (NGS) panel includes 28 genes encoding RBC cytoskeletal proteins, membrane transporter, RBC enzymes, and certain bilirubin metabolism genes. The panel covers the complete coding region of these genes, splice junctions, and, wherever appropriate, deep intronic or regulatory regions are also included. Four hundred fifty-six patients with unexplained hemolytic anemia were evaluated using our NGS panel between 2015 and 2019.

RESULTS

We identified pathogenic/likely pathogenic variants in 111/456 (24%) patients that were responsible for the disease phenotype (e.g., moderate to severe hemolytic anemia and hyperbilirubinemia). Approximately 40% of the mutations were novel. As expected, 45/456 (10%) patients were homozygous for the promoter polymorphism in the UGT1A1 gene, A(TA)₇ TAA (UGT1A1*28). 8/45 homozygous UGT1A1*28 cases were associated with additional pathogenic mutations causing hemolytic anemia, likely exacerbating hyperbilirubinemia. The most common mutated genes were membrane cytoskeleton genes SPTA1, and SPTB, followed by PKLR. Complex interactions between SPTA1 low expression alleles, alpha-LELY and alpha-LEPRA alleles, and intragenic SPTA1 variants were associated with hereditary pyropoikilocytosis and autosomal recessive hereditary spherocytosis in 23/111 patients.

CONCLUSIONS

Our results demonstrate that hemolytic anemia is underscored by complex molecular interactions of previously known and novel mutations in RBC cytoskeleton/enzyme genes, and therefore, NGS should be considered in all patients with clinically unexplained hemolytic anemia and in neonates with hyperbilirubinemia. Moreover, low expression alleles alpha-LELY and alpha-LEPRA should be included in all targeted HHA panels.

ABO hemolytic disease of the newborn: a need for clarity and consistency in diagnosis

The diagnosis of ABO hemolytic disease of the newborn (ABO HDN) has been the subject of considerable debate and clinical confusion. Its use as an overarching default diagnosis for hyperbilirubinemia in all ABO incompatible neonates regardless of serological findings is problematic and lacks diagnostic precision. Data on hemolysis indexed by carbon monoxide (CO) levels in expired air (ETCOc) and blood (COHbc) support an essential role for a positive direct antiglobulin test (DAT) in making a more precise diagnosis of ABO HDN. A working definition that includes ABO incompatibility, significant neonatal hyperbilirubinemia, and a positive DAT is needed to gain clarity and consistency in the diagnosis of ABO HDN. Absent a positive DAT, the diagnosis of ABO HDN is suspect. Instead, a negative DAT in a severely hyperbilirubinemic ABO incompatible neonate should trigger an exhaustive search for an alternative cause, a search that may require the use of targeted gene panels.

Whole-exome sequencing uncovered genetic diagnosis of severe inherited haemolytic anaemia: Correlation with clinical phenotypes

Next-generation sequencing has shed light on the diagnosis of previously unsolved cases of inherited haemolytic anaemia (IHA). We employed whole-exome sequencing to explore the molecular diagnostic spectrum of 21 unrelated Thai paediatric patients with non-thalassemic IHA, presenting hydrops fetalis and/or becoming transfusion-dependent for 1 year or more or throughout their lifespan. Anaemia was detected prenatally, within the first month and the fifth year of life in three, 12 and six patients respectively. Molecular diagnosis obtained from all patients revealed SPTB as the most frequently mutated gene (four reported, three novel), found in 31 of 42 studied alleles. The other two mutated genes identified were ANK1 (three novel) and KLF1 (two reported). Four recurring mutations within exon 29/30 (NM_001024858.2) accounted for the vast majority (90%) of mutated SPTB alleles, biallelic inheritance of which resulted in the most severe phenotypes: hydrops fetalis and life-long transfusion dependency. Dominant ANK1 (n = 3) and SPTB (n = 2) mutations and biallelic class 2 KLF1 mutations (n = 1) led to a shorter period of transfusion dependency. Our study demonstrated that mutated SPTB causing red-cell membranopathy is likely the most common cause of severe non-thalassemic IHA among Thai patients. This urges carrier screening in the population to prevent subsequent, severely affected births.

In Silico Assessment of Tanning Masking Effects on Skin Chromatic Attributes Elicited by Anemia and Hyperbilirubinemia

Changes in skin appearance are among the most recognizable symptoms of a number of medical conditions. The interpretation of such changes, however, may be inadvertently biased by normal physiological processes affecting skin optical properties. In this paper, we assess the impact of one of the most common of these processes, tanning, on variations in skin chromatic attributes elicited by two ubiquitous and serious medical conditions, anemia and hyperbilirubinemia. We employ a first-principles investigation approach centered on the use of predictive computer simulations of light and skin interactions, and on well-established colorimetry methods. In our in silico experiments, we considered skin chromatic attributes resulting from distinct anemia severity levels and hyperbilirubinemia tox-icity stages. Our findings highlight qualitative and quantitative aspects that need to be considered in the visual screening and monitoring of these conditions, notably when they occur with the concomitant presence of tanning-induced changes in the cutaneous tissues' melanin pigmentation and thickness.

Molecular Genetic Screening of Neonatal Intensive Care Units: Hyperbilirubinemia as an Example

Objective

To explore the clinical value of newborn genomic screening (nGS) for neonatal intensive care units (NICU) infants (taking neonatal hyperbilirubinemia as an example).

Methods

Dried blood spots (DBSs) were collected after 72 hours of birth. The tandem mass spectrometry (TMS) screening and Angel Care genomic screening (GS, based on Targeted next-generation sequencing) were performed at the same time.

Results

Ninety-six hyperbilirubinemia newborns were enrolled in this study and none was identified with inborn errors of metabolism (IEM) by TMS, while 6 infants (6.25%, 6/96) were suspected to have a genetic disorder by Angel Care, including 2 cases of glucose-6-phosphate dehydrogenase deficiency (G6PD), and 1 case of maple syrup urine disease type 1B (MSUD1B), autosomal recessive deafness 1A (DFNB1A), Leber hereditary optic neuropathy (LHON), thyroid dyshormonogenesis 6 (TDH6) each. In addition, 44 infants (45.8%) were detected having at least one variant which conferred a carrier status for a recessive childhood-onset disorder. A total of 33 out of 60 variants (55.0%) reported for carrier status were pathogenic (P), 24 (40.0%) were likely pathogenic (LP), and 3 variants were variant of uncertain significance (VUS). Top six common genes of carrier status were GJB2, DUOX2, PRODH, ATP7B, SLC12A3, SLC26A4. Two newborns showed abnormalities in elementary screening of TMS, but were confirmed as false positive after recall. Their results of Angel Care did not found abnormality.

Conclusion

Using neonatal hyperbilirubinemia as an example, genome sequencing screening can find more evidence of genetic variation in NICU newborns, and “Angel Care” is an effective method.

Clinical and Genetic Etiologies of Neonatal Unconjugated Hyperbilirubinemia in the China Neonatal Genomes Project

OBJECTIVE

To investigate the clinical and genetic causes of neonatal unconjugated hyperbilirubinemia.

STUDY DESIGN

We included 1412 neonates diagnosed with unconjugated hyperbilirubinemia (total serum bilirubin >95 percentile for age), from the China Neonatal Genomes Project between August 2016 and September 2019, in the current study. Clinical data and targeted panel sequencing data on 2742 genes including known unconjugated hyperbilirubinemia genes were analyzed.

RESULTS

Among the 1412 neonates with unconjugated hyperbilirubinemia, 37% had severe unconjugated hyperbilirubinemia, with total serum bilirubin levels that met the recommendations for exchange transfusion. Known clinical causes were identified for 68% of patients. The most common clinical cause in the mild unconjugated hyperbilirubinemia group was infection (17%) and in the severe group was combined factors (21%, with infection combined with extravascular hemorrhage the most common). A genetic variant was observed in 55 participants (4%), including 45 patients with variants in genes associated with unconjugated hyperbilirubinemia and 10 patients with variants that were regarded as additional genetic findings. Among the 45 patients identified with unconjugated hyperbilirubinemia-related variants, the genes were mainly associated with enzyme deficiencies, metabolic/biochemical disorders, and red blood cell membrane defects. G6PD and UGT1A1 variants, were detected in 34 of the 45 patients (76%).

CONCLUSIONS

Known clinical causes, which varied with bilirubin levels, were identified in approximately two-thirds of the patients. Genetic findings were identified in 4% of the patients, including in patients with an identified clinical cause, with G6PD and UGT1A1 being the most common genes in which variants were detected.

Regulation of Cytochrome P450 2a5 by Artemisia capillaris and 6,7-Dimethylesculetin in Mouse Hepatocytes

Jaundice is a potentially fatal condition resulting from elevated serum bilirubin levels. For centuries, herbal remedies containing Artemisia capillaris Thunb. including the compound 6,7-dimethylesculetin (DE) have been used in Asia to prevent and treat jaundice in neonates. DE activates an important regulator of bilirubin metabolism, the constitutive androstane receptor (CAR), and increases bilirubin clearance. In addition, murine cytochrome P450 2a5 (Cyp2a5) is known to be involved in the oxidative metabolism of bilirubin. Moreover, treatment of mice with phenobarbital, a known inducer of both CAR and Cyp2a5, increases expression of Cyp2a5 suggesting a potential relationship between CAR and Cyp2a5 expression. The aim of this study is to investigate the influence of Artemisia capillaris and DE on the expression and regulatory control of Cyp2a5 and the potential involvement of CAR. Treatment of mouse hepatocytes in primary culture with DE (50 μM) significant increased Cyp2a5 mRNA and protein levels. In mice, Artemisia capillaris and DE treatment also increased levels of hepatic Cyp2a5 protein. Luciferase reporter assays showed that CAR increases Cyp2a5 gene transcription through a CAR response element in the Cyp2a5 gene promoter. Moreover, DE caused nuclear translocation of CAR in primary mouse hepatocytes and increased Cyp2a5 transcription in the presence of CAR. These results identify a potential CAR-mediated mechanism by which DE regulates Cyp2a5 gene expression and suggests that DE may enhance bilirubin clearance by increasing Cyp2a5 levels. Understanding this process could provide an opportunity for the development of novel therapies for neonatal and other forms of jaundice.

The diagnostic protocol for hereditary spherocytosis-2021 update

Background

Hereditary spherocytosis (HS), a commonly encountered hereditary hemolytic disease, is mostly inherited in an autosomal dominant manner. The clinical manifestations in patients with HS show obvious heterogeneity. Moreover, the sensitivity or specificity of some HS diagnostic tests are not ideal and may easily result in misdiagnosis or missed diagnosis in some patients. The objective of this study was to propose a simple and practical diagnostic protocol, which can contribute to the diagnosis of HS and its differential diagnosis with different types of hemolytic anemia such as thalassemia (THAL), autoimmune hemolytic anemia (AIHA), and glucose‐6‐phosphate dehydrogenase (G6PD) deficiency, thus, to provide an alternative simple and reliable method for better clinical diagnosis of HS.

Methods

Through combing our research with existing experimental technologies and studies, we propose a simple and practical protocol for HS diagnosis, which will help clinicians to improve HS diagnosis.

Results

Compared with the existing HS diagnostic protocols, the HS diagnostic protocol we proposed is simpler. In this new protocol, some experimental tests with ideal diagnostic efficiency are added, such as mean reticulocyte volume (MRV), mean sphered cell volume (MSCV), mean corpuscular volume (MCV), in combination with the observation of clinical manifestations, family investigation, routine tests for hemolytic anemia, genetic testing, and other screening tests.

Conclusion

The HS diagnostic protocol we proposed could improve the clinical practice and efficiency of HS diagnosis.

Hyperbilirubinemia in the Term Infant: Re-evaluating What We Think We Know

This article attempts to highlight contemporary issues relating to term neonatal hyperbilirubinemia and to focus attention on controversial issues and concepts with the potential to effect change in clinical approach. On the one hand, the focus is bilirubin neurotoxicity, which is now known to encompass a wide, diverse spectrum of features. The various aspects of this spectrum are outlined and defined. On the other hand, bilirubin also possesses antioxidant properties. As such, mild hyperbilirubinemia is suggested as actually offering the neonate some protective advantage.

Alterations of Cytochrome P450s and UDP-Glucuronosyltransferases in Brain Under Diseases and Their Clinical Significances

Cytochrome P450s (CYPs) and UDP-glucuronosyltransferases (UGTs) are both greatly important metabolic enzymes in various tissues, including brain. Although expressions of brain CYPs and UGTs and their contributions to drug disposition are much less than liver, both CYPs and UGTs also mediate metabolism of endogenous substances including dopamine and serotonin as well as some drugs such as morphine in brain, demonstrating their important roles in maintenance of brain homeostasis or pharmacological activity of drugs. Some diseases such as epilepsy, Parkinson's disease and Alzheimer's disease are often associated with the alterations of CYPs and UGTs in brain, which may be involved in processes of these diseases via disturbing metabolism of endogenous substances or resisting drugs. This article reviewed the alterations of CYPs and UGTs in brain, the effects on endogenous substances and drugs and their clinical significances. Understanding the roles of CYPs and UGTs in brain provides some new strategies for the treatment of central nervous system diseases.

Exchange transfusion for hemolytic hyperbilirubinemia: could some be averted by emergent administration of an inhibitor of bilirubin production?

OBJECTIVES

The objective of this study is to explore the hypothetical number of neonates where an exchange transfusion (ET) could be prevented by emergency administration of an inhibitor of bilirubin production.

STUDY DESIGN

We identified all neonates who received an ET in our NICUs during the past 12 years. We reviewed the indications for ET and recorded the time between ordering and beginning the exchange.

RESULTS

Forty-six neonates underwent ET, 37 (80.4%) for hemolytic hyperbilirubinemia (36.9 ± 2.9 weeks gestation and 2.5 ± 2.1 days old at ET). The mean delay period was 7.5 ± 3.5 h. Nine (19.6%) had ET not involving bilirubin.

CONCLUSIONS

A trial testing compounds that can inhibit bilirubin production would have about three eligible neonates/years in our system. Since our births are 1% of national, up to 300 neonates/years might qualify for such a study.

Red cell membrane disorders: structure meets function

The mature red blood cell (RBC) lacks a nucleus and organelles characteristic of most cells, but it is elegantly structured to perform the essential function of delivering oxygen and removing carbon dioxide from all other cells while enduring the shear stress imposed by navigating small vessels and sinusoids. Over the past several decades, the efforts of biochemists, cell and molecular biologists, and hematologists have provided an appreciation of the complexity of RBC membrane structure, while studies of the RBC membrane disorders have offered valuable insights into structure-function relationships. Within the last decade, advances in genetic testing and its increased availability have made it possible to substantially build upon this foundational knowledge. Although disorders of the RBC membrane due to altered structural organization or altered transport function are heterogeneous, they often present with common clinical findings of hemolytic anemia. However, they may require substantially different management depending on the underlying pathophysiology. Accurate diagnosis is essential to avoid emergence of complications or inappropriate interventions. We propose an algorithm for laboratory evaluation of patients presenting with symptoms and signs of hemolytic anemia with a focus on RBC membrane disorders. Here, we review the genotypic and phenotypic variability of the RBC membrane disorders in order to raise the index of suspicion and highlight the need for correct and timely diagnosis.

Screening tools for hereditary hemolytic anemia: new concepts and strategies

INTRODUCTION

Hereditary hemolytic anemias are a group of rare and heterogeneous disorders due to abnormalities in structure, metabolism, and transport functions of erythrocytes; they may overlap in clinical and hematological features making differential diagnosis difficult, particularly in mild and atypical forms.

AREAS COVERED

In the present review, the main tools currently adopted in routine hematologic investigation for the diagnosis of hereditary hemolytic anemias are described, together with the new diagnostic approaches that are being to be developed in the next future. Available recommendations in this field together with a systematic review through MEDLINE, EMBASE, and PubMED for publications in English from 2000 to 2020 in regards to diagnostic aspects of hereditary hemolytic anemias have been considered.

EXPERT OPINION

The recent development of specific molecules and treatments for hereditary hemolytic anemias and the increased interest in translational research raised the attention on differential diagnosis and the demand for novel diagnostic assays and devices. Automatic blood cell analyzers, omic-approaches including NGS technologies, and development of new automated tools based on artificial neural networks definitely represent the future strategies in this field.

Laboratory approach to investigation of anemia with a focus on pyruvate kinase deficiency

Anemia is a major health burden worldwide and affects approximately one-third of world's population. It is not a diagnosis; it is a manifestation of an underlying pathophysiology leading to either decreased hemoglobin (Hb), hematocrit (Hct), or red blood cells (RBCs). Iron deficiency anemia is still the most common cause of anemia worldwide. The symptoms are usually due to the underlying compensatory responses to decrease in oxygen delivery to the tissues. Laboratory investigation should start with complete blood count (CBC), reticulocyte count (RC), and peripheral smear evaluation. Further testing depends on these indices, that is, iron parameters and hemoglobinopathies/thalassemia evaluation in microcytic hypochromic anemia, vitamin B12, and folic acid level in macrocytic anemia. Increased RC denotes adequate bone marrow response and points toward hemolytic process and vice versa. Anemia diagnosis can be complex and confusing for the practicing physician. This review tries to give a practical simplistic approach to the diagnosis, focusing mainly on the basic parameters, that is, CBC, RC, and peripheral smear etc. Moreover, we have also tried to provide an update on the pyruvate kinase deficiency, as there has been recent exciting development in the management of these patients.

Genetics and Genomics Approaches for Diagnosis and Research Into Hereditary Anemias

The hereditary anemias are a relatively heterogeneous set of disorders that can show wide clinical and genetic heterogeneity, which often hampers correct clinical diagnosis. The classical diagnostic workflow for these conditions generally used to start with analysis of the family and personal histories, followed by biochemical and morphological evaluations, and ending with genetic testing. However, the diagnostic framework has changed more recently, and genetic testing is now a suitable approach for differential diagnosis of these patients. There are several approaches to this genetic testing, the choice of which depends on phenotyping, genetic heterogeneity, and gene size. For patients who show complete phenotyping, single-gene testing remains recommended. However, genetic analysis now includes next-generation sequencing, which is generally based on custom-designed targeting panels and whole-exome sequencing. The use of next-generation sequencing also allows the identification of new causative genes, and of polygenic conditions and genetic factors that modify disease severity of hereditary anemias. In the research field, whole-genome sequencing is useful for the identification of non-coding causative mutations, which might account for the disruption of transcriptional factor occupancy sites and cis-regulatory elements. Moreover, advances in high-throughput sequencing techniques have now resulted in the identification of genome-wide profiling of the chromatin structures known as the topologically associating domains. These represent a recurrent disease mechanism that exposes genes to inappropriate regulatory elements, causing errors in gene expression. This review focuses on the challenges of diagnosis and research into hereditary anemias, with indications of both the advantages and disadvantages. Finally, we consider the future perspectives for the use of next-generation sequencing technologies in this era of precision medicine.

Infantile Pyknocytosis: End-Tidal CO, %Micro-R Measurements, Next-Generation Sequencing, and Transfusion Avoidance with Darbepoetin

Infantile pyknocytosis is a rare, self-limited, hemolytic condition of unknown pathogenesis. It is diagnosed when a neonate with Coombs-negative hemolytic anemia has abundant pyknocytes and a characteristic clinical course after other hemolytic disorders has been excluded. Previous reports suggest that transfusions might be avoidable in this condition by administering recombinant erythropoietin. We cared for a patient with this disorder where we employed novel diagnostics and therapeutics. Despite these, and a good outcome free of transfusions, we continue to consider the condition to be idiopathic.

How I approach hereditary hemolytic anemia and splenectomy

Hereditary hemolytic anemias (HHA) are a heterogeneous group of anemias associated with decreased red cell survival. While there can be clinical benefit of splenectomy in many cases, splenectomy is not appropriate for all types of HHA. Additionally, there are significant risks during and following splenectomy including surgical risks, postsplenectomy sepsis, and thrombotic complications. This review discusses the diagnostic approach to HHA as well as the role of splenectomy in the management. Surgical approaches and outcomes for total and partial splenectomy are discussed.

RNA sequencing of whole blood in dogs with primary immune-mediated hemolytic anemia (IMHA) reveals novel insights into disease pathogenesis

Immune-mediated hemolytic anemia (IMHA) is a life-threatening autoimmune disorder characterized by a self-mediated attack on circulating red blood cells. The disease occurs naturally in both dogs and humans, but is significantly more prevalent in dogs. Because of its shared features across species, dogs offer a naturally occurring model for studying IMHA in people. In this study, we used RNA sequencing of whole blood from treatment-naïve dogs to study transcriptome-wide changes in gene expression in newly diagnosed animals compared to healthy controls. We found many overexpressed genes in pathways related to neutrophil function, coagulation, and hematopoiesis. In particular, the most highly overexpressed gene in cases was a phospholipase scramblase, which mediates the externalization of phosphatidylserine from the inner to the outer leaflet of cell membranes. This family of genes has been shown to be critically important for programmed cell death of erythrocytes as well as the initiation of the clotting cascade. Unexpectedly, we found marked underexpression of many genes related to lymphocyte function. We also identified groups of genes that are highly associated with the inflammatory response and red blood cell regeneration in affected dogs. We did not find any genes that distinguished dogs that lived vs. those that died at 30 days following diagnosis, nor did we find any relevant genomic signatures of microbial organisms in the blood of affected animals. Future studies are warranted to validate these findings and assess their implication in developing novel therapeutic approaches for dogs and humans with IMHA.

Exome sequencing for diagnosis of congenital hemolytic anemia

Background

Congenital hemolytic anemia constitutes a heterogeneous group of rare genetic disorders of red blood cells. Diagnosis is based on clinical data, family history and phenotypic testing, genetic analyses being usually performed as a late step. In this study, we explored 40 patients with congenital hemolytic anemia by whole exome sequencing: 20 patients with hereditary spherocytosis and 20 patients with unexplained hemolysis.

Results

A probable genetic cause of disease was identified in 82.5% of the patients (33/40): 100% of those with suspected hereditary spherocytosis (20/20) and 65% of those with unexplained hemolysis (13/20). We found that several patients carried genetic variations in more than one gene (3/20 in the hereditary spherocytosis group, 6/13 fully elucidated patients in the unexplained hemolysis group), giving a more accurate picture of the genetic complexity of congenital hemolytic anemia. In addition, whole exome sequencing allowed us to identify genetic variants in non-congenital hemolytic anemia genes that explained part of the phenotype in 3 patients.

Conclusion

The rapid development of next generation sequencing has rendered the genetic study of these diseases much easier and cheaper. Whole exome sequencing in congenital hemolytic anemia could provide a more precise and quicker diagnosis, improve patients’ healthcare and probably has to be democratized notably for complex cases.

Dizygotic twins with prolonged jaundice and microcytic, hypochromic, hemolytic anemia with pyropoikilocytosis

Dizygotic twin males, born at 34 weeks gestation, had prolonged jaundice, microcytic, hypochromic anemia, FABarts hemoglobin, elevated end-tidal CO, and blood films consistent with hereditary pyropoikilocytosis. DNA sequencing revealed both had a heterozygous alpha spectrin (SPTA1) mutation (c.460_462dup) inherited from their asymptomatic mother, plus a 3-base pair duplication in alpha globin (HBA2) (c.364_366dupGTG) inherited from their asymptomatic father.

Laboratory Approach to Hemolytic Anemia

Hemolytic anemias are a group of disorders with varied clinical and molecular heterogeneity. They are characterized by decreased levels of circulating erythrocytes in blood. The pathognomic finding is a reduced red cell life span with severe anemia or, compensated hemolysis accompanied by reticulocytosis. The diagnostic workup or laboratory approach for hemolytic anemias is based on methodical step-wise testing which includes red blood cell morphology, hematological indices with increased reticulocyte count along with clinical features of hemolytic anemias. If conventional laboratory tests are unable to detect the underlying cause of hemolysis, genetic testing is recommended. Sanger sequencing along with conventional testing is the most efficient way to diagnose the underlying genetic causes, especially in thalassemias/hemoglobinopathies, if required. However, hemolytic anemias being highly heterogeneous disorders, next-generation sequencing-based screening is rapidly becoming an efficient way to decipher the etiologies where common causes have been excluded.