GENETIC AND FUNCTIONAL INSIGHTS INTO PROTEINS AND PATHWAYS IN
CONGENITAL DYSERYTHROPOIETIC ANAEMIA TYPE I
Aude-Anaïs Olijnik1, Caroline Scott1, Noemi Roy2, Jill Brown1, Damien Downes1, Sanja Brolih1, Nigel
Roberts1, Errin Johnson3, Raffaele Renella4, Robert Beagrie1, Jim Hughes1, Peter McHugh1, Veronica
Buckle1, Douglas Higgs1 and Christian Babbs1
(1)MRC WIMM, University of Oxford, Oxford, United Kingdom
(2)Dept of Haematology John Radcliffe Hospital, Oxford, United Kingdom
(3)Sir William Dunn School of Pathology, Oxford, United Kingdom
(4)Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
Objectives: Congenital Dyserythropoietic Anaemia type I (CDA-I) is a hereditary anaemia
caused by biallelic mutations in the widely expressed genes CDAN1 and CDIN1. Little is
understood about either protein and it is unclear in which cellular pathways they participate.
Here, we set out to determine the effect of mutations on both causative proteins, test
whether the proteins interact and shed light on the cellular pathway affected in CDA-I.
Methods: Using genetic and functional approaches including immunoprecipitation, western
blotting, immunofluorescence, immunophenotyping and chromatin assays we interrogate the
effect of missense mutations on both causative proteins.
Results: Mutations are enriched in six clusters in Codanin-1 and tend to affect buried residues.
Population genetics suggests CDA-I may be more common than currently predicted. CDIN1
relies on Codanin-1 for stability and both proteins interact to form an obligate complex in
cells. In cultured patient cells, enucleation defects appear to be more severe in patients with
mutations in CDIN1, indicating a genotype/phenotype correlation. Both proteins are enriched
in the nucleolus and we detect an abnormal distribution of nucleolar components together
with a reduced nucleolar output in patient erythroblasts.
Conclusions: Protein stability and interaction data suggest CDIN1 may be the key determinant
of CDA-I. The surprisingly high predicted incidence of CDA-I suggests better ascertainment
would lead to improved patient care. Localisation of both causative proteins to the nucleolus
and impaired nucleolar output implicate defects in nucleolar function as a contributory factor
in this disease, as has been shown for other erythroid-specific disorders.
POSTER 1