In the heterozygous state, band-3 Coimbra causes typical hereditary spherocytosis (SPH4; 612653) and is associated with partial deficiency of band-3 and, as a secondary phenomenon, of protein 4.2 (177070) (Alloisio et al., 1997). Band 3 Coimbra is caused by a GTG-to-ATG change in exon 13 of the SLC4A1 gene, resulting in a val488-to-met substitution.
Ribeiro et al. (2000) reported severe hereditary spherocytosis and renal tubular acidosis (611590) associated with total absence of band-3 in an infant homozygous for the Coimbra mutation. Because the fetus stopped moving near term, an emergency cesarean section was performed and a severely anemic, hydropic female baby was delivered. She was resuscitated and initially kept alive with respiratory assistance and hypertransfusion therapy. Band 3 and protein 4.2 were absent; spectrin, ankyrin, and glycophorin A were significantly reduced. Renal tubular acidosis was detected by the age of 3 months. Nephrocalcinosis appeared soon thereafter. With regular blood transfusions and daily bicarbonate supplements, the child was doing 'reasonably well' at the age of 3 years.
