Band 3 nullVIENNA , a novel homozygous SLC4A1 p.Ser477X variant causing severe hemolytic anemia, dyserythropoiesis and complete distal renal tubular acidosis.

We describe the second patient with anionic exchanger 1/band 3 null phenotype (band 3 nullVIENNA ), which was caused by a novel nonsense mutation c.1430C>A (p.Ser477X) in exon 12 of SLC4A1. We also update on the previous band 3 nullCOIMBRA patient, thereby elucidating the physiological implications of total loss of AE1/band 3. Besides transfusion-dependent severe hemolytic anemia and complete distal renal tubular acidosis, dyserythropoiesis was identified in the band 3 nullVIENNA patient, suggesting a role for band 3 in erythropoiesis. Moreover, we also, for the first time, report that long-term survival is possible in band 3 null patients.