A complex comprising C15ORF41 and Codanin-1: the products of two genes mutated in congenital dyserythropoietic anaemia type I (CDA-I)

Congenital dyserythropoietic anaemia (CDA) type I is a rare blood disorder characterised by moderate to severe macrocytic anaemia and hepatomegaly, with spongy heterochromatin and inter-nuclear bridges seen in bone marrow erythroblasts. The vast majority of cases of CDA type I are caused by mutations in the CDAN1 gene. The product of CDAN1 is Codanin-1, which interacts the histone chaperone ASF1 in the cytoplasm. Codanin-1 is a negative regulator of chromatin replication, sequestering ASF1 in the cytoplasm, restraining histone deposition and thereby limiting DNA replication. The remainder of CDA-I cases are caused by mutations in the C15ORF41 gene, but very little is known about the product of this gene. Here, we report that C15ORF41 forms a tight, near-stoichiometric complex with Codanin1 in human cells, interacting with the C-terminal region of Codanin-1. We present the characterisation of the C15ORF41-Codanin-1 complex in humans in cells and in vitro, and demonstrate that Codanin-1 appears to sequester C15ORF41 in the cytoplasm as previously shown for ASF1. The findings in this study have major implications for understanding the functions of C15ORF41 and Codanin-1, and the aetiology of CDA-I.

Chronic Recurrent Multifocal Osteomyelitis and Related Diseases-Update on Pathogenesis

PURPOSE OF REVIEW

We focus on recent advances in the understanding of the genetic, molecular, immunologic, and environmental factors implicated in the pathogenesis of autoinflammatory bone diseases including the syndromic and non-syndromic forms of chronic recurrent multifocal osteomyelitis (CRMO).

RECENT FINDINGS

Evidence implicating the IL-1 pathway in the pathogenesis of the Mendelian forms of CRMO is growing. LIPIN2 can regulate the NLRP3 inflammasome by affecting P2X7 receptor activation, and intracellular cholesterol can modulate P2X7R currents. Work in a mouse model of CRMO demonstrates that dietary manipulation can alter the microbiome and protect these mice from the development of sterile osteomyelitis in vivo. Although the genetic and immunologic basis of non-syndromic CRMO remains only partially understood, the IL-1 pathway is central to the pathogenesis in the syndromic autoinflammatory bone disorders. Recent work implicates lipids and the microbiome in sterile osteomyelitis.

Dyserythropoiesis in 105 patients with visceral leishmaniasis

Hematologists in the developing world are increasingly involved in diagnosing parasitic diseases that involve the bone marrow. With a worldwide annual incidence of half a million cases and 12 million infected people, visceral leishmaniasis is one such serious disease. It mainly affects malnourishedand economically underprivileged children. Recently, this disease has been seen in acquired immunodeficiency syndrome patients and in travelers to endemic areas. Over an 18-year period, 442 marrow examination requests were received by our department, and 105 cases of visceral leishmaniasis were diagnosed from findings of Leishman-Donovan bodies. Prominent nuclear dyserythropoiesis was shown in 17 patients, 14 of whom had the frank type that is uniquely seen in congenital dyserythropoietic anemia type II. Most of these cases showed an extremely low degree of marrow parasitemia. This degree of nuclear dyserythropoiesis was not found in the majority of the marrows in which parasites were more easily detected. There is a direct and negative correlationbetween frank nuclear dyserythropoiesis and marrow parasitemia. Extended microscopical examination is recommended for the detection of Leishman-Donovan bodies in cases of suspected visceral leishmaniasis when frank dyserythropoiesis is a prominent feature. It is possible that both frank nuclear dyserythropoiesis and marrow parasitemia are etiologically under the influence of a common chemokine or cytokine.

Piebaldism associated with congenital dyserythropoietic anemia type II (HEMPAS)

Congenital dyserythropoietic anemias (CDAs) are a group of relatively rare inherited anemias. They are characterized by ineffective erythropoiesis and classified as three major groups and a number of variants. CDA type II, also known as hereditary erythroblastic multinuclearity with a positive acidified serum test (HEMPAS), is the most frequent one. A number of associations with CDA II have been reported, although each described only one or a few patients. Here we presented a piebald woman with vaginal atresia who was tested for anemia and diagnosed as CDA type II. Piebaldism and anemia association were previously described in the mouse. Our case was the first that shows the features of both piebaldism and CDA in the same patient. This association may suggest a stem cell defect to cause both hematopoietic and cutaneous manifestations.

Identification of a novel simian parvovirus in cynomolgus monkeys with severe anemia. A paradigm of human B19 parvovirus infection

Although human B19 parvovirus infection has been clearly associated with a number of distinct syndromes (including severe anemia, abortion, and arthritis), detailed knowledge of its pathogenesis has been hindered by the lack of a suitable animal model. We have identified a novel simian parvovirus in cynomolgus monkeys with severe anemia. Sequencing of a 723-bp fragment of cloned viral DNA extracted from serum revealed that the simian parvovirus has 65% homology at the DNA level with the human B19 parvovirus but little homology with other known parvoviruses. Light microscopic examination of bone marrow from infected animals showed intranuclear inclusion bodies, and ultrastructural studies showed viral arrays characteristic of parvoviruses. Another striking feature was the presence of marked dyserythropoiesis in cells of the erythroid lineage, raising the possibility that B19 parvovirus infection may underlie related dyserythropoietic syndromes in human beings. Affected animals had concurrent infection with the immunosuppressive type D simian retrovirus, analogous to HIV patients who develop severe anemia because of infection with B19 parvovirus. The remarkable similarities between the simian and B19 parvoviruses suggest that experimentally infected cynomolgus monkeys may serve as a useful animal model of human B19 infection.

[Morphological studies of erythrocytes in congenital dyserythropoietic anemia type II]

The etiology of congenital dyserythropoietic anemia (CDA) type II is unknown. The diagnosis is based on morphologic and immunologic criteria. We present three girls with well documented CDA II who were followed for 5-8 years. The anemia was mild, progressive body iron overload was found. In none of the girls splenectomy was indicated. Morphologic features of ++erythrocytes and bone marrow erythroid cells were studied by means of light and electron microscopy. Up to 45% of erythrocytes showed invaginations with endocytic cisterns and shape abnormalities (echinocytes, anisocytosis, microcytosis). Typical abnormalities of the external surface of RBC membrane: invaginations, depressions, pits and plaques were shown in the scanning electron microscopic studies. Our studies indicate that the morphological features of erythrocyte in our patients may be consequence of the biochemical changes in the membranes and may contribute to the shortened life span of erythrocytes in patients with CDA II.