Modulation of clinical expression and band 3 deficiency in hereditary spherocytosis.
We present two novel alleles of the anion-exchanger 1 (AE1) gene, allele Coimbra and allele Mondego. Allele Coimbra (V488M, GTG --> ATG) affects a conserved position in the putative second ectoplasmic loop of erythrocyte band 3. In 15 simple heterozygotes, it yielded a mild form of hereditary spherocytosis (HS) with band 3 deficiency (-20% +/- 2%) and a reduced number of 4,4'-diisothiocyano-1,2-diphenylethane-2,2'-disulfonate (H2DIDS) binding sites (-35%). However, two additional heterozygotes presented with an aggravated HS and a more pronounced reduction of band 3 (-40%) and of H2DIDS binding sites (-48%). They carried, in trans to allele Coimbra, allele Mondego, defined by two mutations: E40K, GAG --> AAG, the known mutation Montefiore, and P147S, CCT --> TCT, a novel mutation, both located in the cytoplasmic domain of band 3. Allele Mondego itself resulted in no clinical or hematologic HS signs in the simple heterozygous state. Yet it yielded a slight decrease in band 3 (-6% to -12%) and in the number of H2DIDS binding sites (-19%). Thus, the more pronounced decrease in band 3 in the two compound heterozygotes derived from the additive effects of two unequally expressed AE1 alleles, resulting in a more severe clinical picture.
Alloisio
N
N
Laboratoire de Génétique Moléculaire Humaine, Centre National de la Recherche Scientifique, URA 1171, Institut Pasteur de Lyon, France.
Texier
P
P
Vallier
A
A
Ribeiro
M L
ML
Morlé
L
L
Bozon
M
M
Bursaux
E
E
Maillet
P
P
Gonçalves
P
P
Tanner
M J
MJ
Tamagnini
G
G
Delaunay
J
J
D000483:Alleles; D001457:Anion Exchange Protein 1, Erythrocyte / Q000172:deficiency / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D010375:Pedigree; D013103:Spherocytosis, Hereditary / Q000235:genetics*
D001457:Anion Exchange Protein 1, Erythrocyte