Pathogenesis of Congenital Dyserythropoietic Anaemia Type I

Supervisors:  Dr Christian Babbs, Prof Irene Roberts and Prof Richard Gibbons

Project Overview

The focus of this project is on the pathogenesis of the recessive disorder Congenital Dyserythropoietic Anaemia Type I (CDA-I), one of the three main types of congenital dyserythropoietic anaemia (CDA). CDAs arise in childhood and are clinically characterised by moderate to severe macrocytic anaemia and reticulocytopenia, arising from ineffective erythropoiesis. There are also morphological abnormalities of erythroblasts that include inter-nuclear bridging, a disease-specific pattern of abnormal heterochromatin and cells with multiple nuclei. Currently mutations in two genes, C15ORF41 and CDAN1 (which encodes Codanin) are known to cause this disorder. Although these genes are ubiquitously expressed and appear to be indispensible for cell survival, remarkably, when they are mutated, abnormalities are only seen in developing erythroblasts. Our laboratory is the UK reference laboratory for investigation of CDA-I and the repository includes material from >20 different families in which at least one individual manifests anaemia with characteristics indicating CDA-I. It is notable that the clinical presentation and morphological abnormalities of CDA-I caused by lesions in either CDAN1 or C15ORF41 are currently indistinguishable, suggesting these proteins act via the same biological pathway.

This project will involve the study of mutant erythroid progenitor cells harbouring mutations and affinity purification tags in either C15ORF41 orCDAN1. The cells will be induced to enter terminal differentiation so that the role of these proteins during erythroid maturation can be interrogated. The work will also involve genome editing erythroid precursors using CRISPR/Cas9 methodology to introduce mutations and affinity tags into genes of interest. This will allow their localization to be established in an appropriate cell-type and at physiologically relevant levels. The pathway in which these proteins participate is currently unclear, however, there is some evidence that it may affect replication-linked chromatin assembly or the resolution of abnormal DNA structures that result from stalled replication forks or DNA catenanes which may from incompletely replicated centromeric repeats. The project will aim to gain insight into the roles of the normal and mutant proteins in in vitro differentiated erythroblatsts using an immunoprecipitation and mass-spectrometry based techniques. Using these approaches this work is likely to elucidate the molecular pathology of CDA-I and shed light on the roles played by Codanin-1 and C15ORF41 in normal and pathological erythropoiesis.

Training Opportunities

Theme

Genes, Genetics, Epigenetics & Genomics and Haematology

For further information, please contact

Christian.babbs@imm.ox.ac.uk