+ Correspondence should be addressed to CAA (c.albers@gen.umcn.nl), WHO (who1000@cam.ac.uk) or AC (as889@cam.ac.uk) . Author Contributions: AC performed zebrafish knock down, analysis of zebrafish gene sequence; LHW, collected clinical cases with anti-Vel, performed confirmatory Sanger sequencing and phenotyping by flow cytometry and haem-agglutination; JCS performed confirmatory Sanger sequencing and analyzed the genotyping data; MK and PB analyzed the RNA-Sequencing data; PAS performed SMIM1 transfection experiments, MF and SF performed isolation of precursor cells; BS, GJ, AT and NG performed the analysis of the evolutionary conservation of the SMIM genes; AAS performed genotyping; EA, erythroblast culture and transfection; EB performed zebrafish knock down experiment with input from DS; HS, HHWS, VGH, NV performed cell culture experiments and performed EMSA's and transfection experiments and Q-PCR for SMIM1; RSNF, JK, HJW and LF performed eQTL and gene ontology analysis; AG, MN, JP, JGS, HLJ, KR, MdH were responsible for identification of Vel-negative and Vel-weak individuals by typing >360,000 samples; HHDK performed RNA-Seq with supervisory input from HGS who leads and coordinates the BluePrint epigenome project; GK supervised exome-sequencing; AR analysed expression data from whole genome expression arrays and RNAseq; HS expression data and vectors; DS iron homeostasis and other relevant laboratory measurements; D.St. oversaw zebrafish experiments. NS provided pre-publication access to red blood cell GWAS meta-analysis; PH eQTL analysis, expression data, SMIM1 vectors, pre-publication access to red blood cell GWAS meta-analysis; EvdS and WHO designed the study, CAA performed exome sequence analysis, Sanger sequence analysis, genetic analysis and statistical analysis; AC, LHW, EvdS, WHO and CAA wrote the paper.

No abstract

This workshop initiated a standardization process for extraction of cff DNA in maternal plasma. The highest yield was obtained by the QIAamp DSP Virus Kit, a result that will be evaluated in more detail in future studies.

Weak Vel expression levels are caused by multiple genetic factors in SMIM1 and probably also by other genetic or environmental factors. Due to the variation in Vel expression levels, serologic determination of the Vel- phenotype is difficult and a genotyping assay targeting the c.64_80del deletion in SMIM1 should be used to screen donors for the Vel- phenotype.