An Unusual Case of Multifactorial Hemolytic Anemia: A Complex Interaction Between Genetic and Autoimmune Factors

Abstract

Hemolytic anemias (HAs) encompasses a heterogeneous group of disorders with either congenital or acquired etiologies. We present a complex case of a 27-year-old woman with hemolytic anemia of multifactorial origin, involving both inherited RBC membrane defects and multiple autoimmune comorbidities. Genetic testing identified heterozygous variants in SPTA1 and SBDS, consistent with carrier status for hereditary elliptocytosis and Shwachman–Diamond syndrome. The patient was also diagnosed with Caspr2-positive Isaacs syndrome, systemic lupus erythematosus, seronegative antiphospholipid syndrome, and anti-aquaporin-4 antibody-positive optic neuritis. Despite extensive immunosuppressive and immunotherapic treatment and splenectomy, the clinical course was marked by recurrent hemolytic crises, thrombotic complications, and progressive neurological involvement, ultimately leading to death. Our experience highlights the challenges posed by the diagnosis and management of HAs, underlining the relevance of a multidisciplinary and personalized approach.

1. Introduction

Red blood cells (RBCs) have a lifespan of 120 days. A reduction in their half-life leads to hemolytic anemia (HA), which is classified in hemoglobinopathies, membranopathies, enzymopathies, immune-mediated anemias (AIHAs), and extrinsic non-immune anemias. Membranopathies are caused by an inherited protein deficit leading to increased RBC destruction. AIHA is further divided in warm (65%), cold (29%), and mixed (5%) types. It can be primary or secondary to other underlying disorders. The direct antiglobulin test (DAT) can further classify AIHA into DAT-positive (90–98%) and DAT-negative (2–10%) [1,2].

However, classification systems have inherent limitations, as multiple factors can simultaneously contribute to hemolysis. In this regard, we report a particularly complex case, showing the importance of and need for a multidisciplinary approach to diagnosis and treatment.

2. Case Report

A 27-year-old woman with anorexia nervosa and Caspr2-autoantibody-positive Isaacs syndrome was referred to our center in January 2017 for hemolytic anemia, splenomegaly (LD 15 cm), and gallstones. Laboratory results included hemoglobin 2.9 g/dL, Mean Corpuscular Volume 107 fl, White Blood Cells 5800/mmc, Platelets 85,000/mmc, reticulocytes 6%, total bilirubin 2.18 mg/dL, direct bilirubin 0.9 mg/dL, non-detectable haptoglobin, LDH 4213 IU/L, vitamin B12, and folate in the normal range. DAT, namely the indirect antiglobulin test, and ektacytometry results were negative. Th glycerol lysis test showed the increased osmotic fragility of RBCs without membrane protein deficiency. Paroxysmal nocturnal hemoglobinuria was excluded. Blood smear showed anysopoikilocitosis and stomatocytes, bone marrow smear erythroid hyperplasia, megaloblastosis, dyserythropoyesis, and 9% ring sideroblast. Cytogenetics showed a normal female karyotype. Sequencing results from the 86-gene RedPlex_rev.2 panel [3] revealed a missense variant in heterozygous state of SPTA1 (p. R568H) and a missense variant in the heterozygous state of SBDS (p. K62*), suggesting a diagnosis of carrier of Shwachman–Diamond syndrome (SDS) and elliptocytosis type II. A bone marrow biopsy showed marked ectasia of the sinusoids, whose walls and RBCs within were positive for complement factor C4d and IgG. The initial treatment was based on corticosteroids, intravenous immunoglobulins, mycophenolate mofetil, vitamin support, and blood transfusions, without reaching transfusion independence. At the end of November 2021, an increase in the spleen size (LD 20.5 cm) with splenic infarcts led to emergency splenectomy and concomitant cholecystectomy. The Platelet count normalized postoperatively. Histological examination of the spleen was consistent with splenomegaly secondary to hemolytic anemia and showed no evidence of neoplasia or extramedullary erythropoiesis. Thereafter, Rituximab therapy (375 mg/m² weekly for a month) was started in January 2022 due to the persistence of hemolytic anemia, complicated by recurrent venous thrombosis (VTE), which led to the amputation of four toes on the right foot, despite anticoagulant therapy. Only later was it found that she had seronegative anti-phospholipid syndrome (atypical antibodies), and she was diagnosed with SLE and switched to acenocumarol. This therapy led to transfusion independence, with Hb values consistently above 10 g/dL until February 2022, when she was admitted to the emergency room for lower limb paralysis, experiencing a new hemolytic crisis associated with the flare-up of neurologic symptoms. During their recovery, the patient was diagnosed with anti-aquaporin-4 (AQP4) antibody-positive optic neuritis and treatment with Eculizumab was started, after a course of 1 g/kg of methylprednisolone for 5 days, 1 g/kg of intravenous immunoglobulins for two days, and 5 sessions of plasmapheresis. Thereafter, the patient was transfusion-independent until a new emergency room admission on 6 June 2023 for the relapse of hemolytic anemia, pneumonia, and PICC-related thrombosis in the right cardiac auricle that led to her death in August 2023.

Figure 1 provides a comprehensive summary of the patient’s clinical course, outlining key events and therapeutic interventions over time.

3. Discussion

HAs represent a heterogeneous group of disorders characterized by the premature destruction of red blood cells (RBCs), which can result from a variety of genetic and acquired causes.

The patient presented with anemia, splenomegaly, and gallstones, which are the hallmark features of HAs. The initial diagnostic workup led to the identification of heterozygous missense variants in SPTA1 (p. R568H) and SBDS (p. K62*), suggesting the status of carrier for hereditary elliptocytosis and Shwachman–Diamond syndrome. Furthermore, the bone marrow biopsy showed sinusoid walls and RBCs positive for complement factor C4d and IgG. Elliptocytosis is one of the most common causes of inherited RBC membrane disorders and is characterized by the weakening of horizontal interactions within the membrane cytoskeleton, compromising the mechanical resilience of RBCs [4]. SDS is an autosomal recessive disorder that presents with the common triad of exocrine pancreatic dysfunction, skeletal abnormalities, and bone marrow dysfunction, which can lead to hemolysis secondary to underlying ineffective erythropoiesis and dyserythropoiesis [5]. Notably, the bone marrow smear exhibited myelodysplastic features, although these were insufficient for a definitive diagnosis of myelodysplastic syndrome (MDS). A possible contributing factor was anorexia nervosa, which has been associated with reversible bone marrow changes that can mimic MDS [6].

These findings suggested the presence of a multifactorial, congenital, and autoimmune causes (Figure 2). The autoimmune component was further supported by the temporal correlation between hemolytic episodes and flare-ups of Isaacs syndrome.

Isaacs syndrome is a rare condition characterized by continuous muscle twitching and myokymia, muscle hypertrophy, weight loss, and hyperidrosis. This syndrome is due to a dysfunction in voltage-gated potassium channels (VGKCs), and in at least 38–50% of patients there are autoantibodies against VGCKs, frequently directed against leucine-rich glioma-inactivated protein 1 (Lgi1) and contactin-associated protein 2 (Caspr2), proteins that are reported to associate with Kv1s [7].

Although there are no reports of a possible association between AHIA and Isaacs syndrome, the clinical course made us hypothesize that the autoantibodies against VGCKs may target epitopes shared with potassium channels expressed on the surface of RBCs, potentially contributing to immune-mediated hemolysis.

After an initial response to immunosuppressive treatments, the clinical course was complicated by thrombotic events and transfusion dependence. Then, the patient was diagnosed with seronegative antiphospholipid syndrome, systemic lupus erythematosus (SLE), and anti-aquaporin-4 (AQP4)-antibody-positive optic neuritis.

The progressive worsening of autoimmune comorbidities led to the worsening of anemia and ultimately to her death.

This case highlights the diagnostic and therapeutic challenges in managing multifactorial hemolytic anemia, in which it is difficult to identify and treat all the concurrent causes. The management of patients with a genetic predisposition to hemolytic anemia associated with autoimmune diseases requires an integrated and personalized approach. One viable strategy could be early allogeneic stem hematopoietic stem cell transplantation (allo-HSCT) [8,9]. However, large studies are necessary to identify patients who may benefit from allo-HSCT.