Diamond Blackfan anaemia: apparent relapse due to B19 parvovirus

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Diagnosing and treating Diamond Blackfan anaemia: results of an international clinical consensus conference

Diamond Blackfan anaemia (DBA) is a rare, genetically and clinically heterogeneous, inherited red cell aplasia. Classical DBA affects about seven per million live births and presents during the first year of life. However, as mutated genes have been discovered in DBA, non-classical cases with less distinct phenotypes are being described in adults as well as children. In caring for these patients it is often difficult to have a clear understanding of the treatment options and their outcomes because of the lack of complete information on the natural history of the disease. The purpose of this document is to review the criteria for diagnosis, evaluate the available treatment options, including corticosteroid and transfusion therapies and stem cell transplantation, and propose a plan for optimizing patient care. Congenital anomalies, mode of inheritance, cancer predisposition, and pregnancy in DBA are also reviewed. Evidence-based conclusions will be made when possible; however, as in many rare diseases, the data are often anecdotal and the recommendations are based upon the best judgment of experienced clinicians. The recommendations regarding the diagnosis and management described in this report are the result of deliberations and discussions at an international consensus conference.

The natural history of severe anemia in cartilage-hair hypoplasia

Anemia is seen in over 80% of patients with cartilage-hair hypoplasia (CHH). While this is usually mild and self-limited, some patients demonstrate a severe, persistent anemia resembling that seen in Diamond-Blackfan anemia (DBA). This paper examines the natural history of 12 patients with CHH and severe anemia. Phenotypic features and mutation data (where available) were reviewed, but no significant differences were found that predicted severe anemia. Severe anemia is estimated to occur in approximately 6% of CHH patients and is permanent in more than half of these patients. Thrombocytosis, though not previously reported in CHH, was noted in five patients, similar to that seen in DBA. The role of possible gene-gene and gene-environment interactions is discussed.

Diamond-Blackfan Anaemia: an overview

Diamond Blackfan Anaemia (DBA) is a congenital disease characterised by defective erythroid progenitor maturation. It is usually diagnosed during the first year of life. The main clinical sign is profound isolated normochromic or macrocytic anaemia, with normal numbers and function of the other haemopoietic cells. Reticulocyte counts in patients with DBA are very low. Bone marrow reflects the defective erythropoiesis, showing a very low number of erythropoietic precursors and a reduction of erythroid burst-forming unit progenitor cells. The proliferation and differentiation of the other lineages are normal. More than one-third of patients have malformations, most often involving the upper limbs and head, and the urogenital or cardiovascular systems. However, the link between these malformations and defective erythropoiesis is unclear and a defect in a molecule acting on both early embryonic development and haematopoiesis has been proposed. Whereas most cases are sporadic, inheritance is observed in 10% of patients, with a dominant or, more rarely, recessive pattern. One locus on chromosome 19q13.2 encoding ribosomal protein S19 accounts for a quarter of patients with either the dominant or the sporadic form. Families not linked with this locus have also been described. The diagnosis of DBA may be difficult and differential diagnoses include Fanconi's anaemia and acquired erythroid aplasias. Erythrocyte adenosine deaminase levels are generally high in DBA patients, which may help in the diagnosis, but they are not pathognomic. Corticosteroids are the main treatment option in DBA and these agents induce erythropoiesis in over 60% of patients. Some patients achieve complete remission, which may be either corticosteroid-induced or spontaneous. The increased in vitro erythropoiesis occasionally induced by the addition of specific cytokines, namely interleukin (IL)-3 and stem cell factor (SCF), has suggested their use in vivo. However, few patients have responded to IL-3, whereas SCF administration, though interesting in theory, has not yet been attempted. Patients who do not respond to corticosteroids and those who have to discontinue treatment because of adverse events must rely on long term transfusions, and are thus exposed to all of the associated complications. Bone marrow or cord blood transplantation has been performed in some patients. The former approach is burdened with severe complications and high mortality.

Human parvovirus B19 infection in organ transplant recipients

We report a 61-yr-old kidney transplant recipient with human Parvovirus B19 (HPV B19) infection presenting as a severe pancytopenia 1 month after transplantation. Bone marrow aspiration revealed severe erythroid hypoplasia with giant and dystrophic proerythroblasts. Bone marrow cells were positive for HPV B19 DNA detected by polymerase chain reaction (PCR). Pancytopenia resolved shortly after administration of intravenous immunoglobulins. Nineteen cases of HPV B19 infection in organ transplant recipients have been so far reported in the literature. Immunocompromised patients should be considered at risk from developing symptomatic HPV B19 infections. In such patients, specific anti-HPV B19 IgM and IgG antibodies may be absent or transient and therefore their negativity cannot rule out the diagnosis of HPV B19 infestation. Bone marrow smear morphological findings may suggest the diagnosis but testing for viral DNA by PCR is mandatory. Patients may spontaneously recover. However, since specific anti-viral therapy is not currently available, intravenous immunoglobulin administration appears to be the more efficacious treatment.

Hematologic manifestations of viral infections

Many infections have an impact on the hematologic system. There also are many noninfectious processes associated with abnormalities of the blood and iatrogenic causes such as pharmacologic therapy that also may affect the marrow or circulating cellular elements. Viral disease may impact on one or more components of blood, and familiarity with these associations can assist in anticipating the course of disease and reducing the need to seek out other etiologies for the usually transient hematologic abnormalities that often occur in patients with viral infections.

Parvovirus B19 infection and Diamond-Blackfan anaemia

It is the purpose of the study to report the frequency of parvovirus in children with a diagnosis of Diamond-Blackfan anaemia and to discuss the possible aetiological role of parvovirus in Diamond-Blackfan anaemia. We found parvovirus DNA in 3 of 11 bone marrow smears. Giant pronormoblasts showed low sensitivity (33%) and poor specificity (75%). The presence of giant pronormoblasts was associated with a very high myeloid:erythroid ratio, and may not be specific for parvovirus infection, but a feature of severely suppressed erythropoiesis. The three parvovirus-positive patients were the only children who experienced a remission, and who are free of medication. The seven surviving parvovirus-negative patients are all currently on steroid treatment.

Parvovirus: the expanding spectrum of disease

Treatment of parvovirus infections among immunocompromised hosts using immunoglobulin has provided the clinician with a useful therapeutic tool but has also highlighted the problems concerning chronic disease states. The discovery of the human parvovirus B19 in 1975 and subsequent studies of its effects in humans have identified this virus as the causative agent of a broad spectrum of diseases. Recent improvements regarding the development of sensitive PCR techniques and methods for cultivation have provided new insight into its pathogenic role, its virology and immunology, and the varied clinical manifestations. The current state of knowledge concerning parvovirus enabled us to divide the long list of diseases caused by this virus into three main categories: (1) disease found among normal hosts (asymptomatic disease, erythema infectiosum, arthropathy, hydrops fetalis), (2) hematologic diseases (aplastic crisis, chronic anemia, idiopathic thrombocytopenic purpura, transient erythroblastopenia of childhood, Diamond-Blackfan anemia) and, finally, (3) a heterogeneous group of diseases, in which the etiologic role of parvovirus is less clear and sometimes putative (neurologic disease, rheumatologic disease, vasculitic and myocarditic syndromes). In particular, arthropathy, hydrops fetalis and the hematologic disorders may be of pediatric concern. Consequently, it is of paramount importance that in all of these cases the clinician includes parvovirus as a differential diagnosis.