The authors would like to apologize for any inconvenience caused. “
“Congenital dyserythropoietic anemia type II (CDA II, OMIM 224100) is a genetic hyporegenerative anemia characterized by ineffective erythropoiesis and distinct morphological abnormalities of the erythroblasts in the bone marrow (BM). Anemia of variable degree, jaundice and splenomegaly are common

clinical findings [1]. This condition belongs to COPII-related RO4929097 order human genetic disorders [2]. It is due to mutations in SEC23B (chr 20p11.23), a component of COPII complex, the core trafficking machinery of the endoplasmic reticulum-Golgi [3]. Approximately 60 different causative mutations have been described, localized along the entire coding sequence of the gene [1], [4], [5] and [6]. The most frequent are nucleotide substitutions (75% missense/nonsense), whereas frameshift and splicing mutations were observed in 15% and 10% respectively. The vast majority of patients have two mutations (in the homozygous or compound heterozygous state), according to the pattern of autosomal recessive inheritance. In no case homozygosity or compound heterozygosity for two nonsense mutations was found, a situation likely to be lethal. However,

few cases with two hypomorphic mutations have been described so far [4] and [5]. Here we characterize three novel CDA II cases, two of them with fully hypomorphic genotype. We demonstrated a compensatory mechanism SEC23A-mediated of SEC23B hypo-expressed alleles. Diagnosis of CDA II was based on history, clinical findings, laboratory data, morphological analysis of aspirated bone marrow and find more whenever possible on evidence of hypoglycosylated band 3 by SDS-PAGE. Samples were obtained after informed consent for the studies, according to the Declaration of Helsinki. Whenever possible, relatives were investigated. Genomic DNA and mutational screening were performed as previously described [4]. Prediction analyses for splice

site mutations were performed by web server tools, splice site prediction by neural network (http://www.fruitfly.org/seq_tools/splice.html) 3-mercaptopyruvate sulfurtransferase and human splicing finder (http://www.umd.be/HSF/) (Table 2). RNA isolation from peripheral blood mononuclear cells (PBMCs), cDNA preparation and quantitative real-time (qRT)-PCR were performed as described [7]. Relative gene expression was calculated by using the 2− ΔCt method, while the mean fold change = 2− (average ΔΔCt) was assessed using the mean difference in the ∆Ct between the gene and the internal control [8]. SEC23B coding sequence was covered by five overlapping PCR fragments and amplified by KAPA2G Robust HotStart ReadyMix (Kapa Biosystems, Cape Town, South Africa). Sequence primers are available on request ([email protected]). Protein extraction from PBMCs and western blotting (WB) were performed as previously described [7] and [9]. A specific rabbit anti-SEC23B antibody (1:500) (BioLegend, San Diego, CA) was used.