Hereditary pyropoikilocytosis and elliptocytosis in a white French family
with the spectrin alpha I/74 variant related to a CGT to CAT codon change
(Arg to His) at position 22 of the spectrin alpha I domain
M Garbarz, MC Lecomte, C Feo, I Devaux, C Picat, C Lefebvre, F Galibert, H Gautero, O Bournier and C Galand
INSERM U.160, Association Claude Bernard, Hopital Beaujon, Clichy, France.
We describe a white French family in which 12 subjects presented with
hereditary elliptocytosis (HE) or hereditary pyropoikilocytosis (HPP).
Eight of these subjects were shown to be heterozygous for a spectrin (Sp)
alpha I/74 variant, as demonstrated by analysis of partial tryptic
digestion fragments of spectrin. This abnormal peptide pattern was
associated with a decreased ability of Sp dimers to self-associate. In this
kindred, in which four generations were available for study, the clinical
expression varied from mild HE to HPP with an intermediate status of
hemolytic HE. The severity of the disease appeared to be correlated both
with the estimated amount of variant Sp (42% to 65%) and the excess of Sp
dimers found in the membrane (30% to 51%, with a normal value of 3.7% +/-
1.6%). Reassociation studies using isolated Sp alpha and beta chains from
an affected patient and an unaffected control subject showed that the Sp
alpha I/74 Kd abnormal tryptic peptide resulted from a defect in the Sp
alpha chain. Partial amino acid sequencing showed that the Sp alpha I/74 Kd
peptide resulted from cleavage at lysine residue 42 of the Sp alpha I/80 Kd
domain. Knowledge of the exon/intron organization of the human alpha Sp
gene allowed us to amplify by the polymerase chain reaction the second exon
of the alpha Sp gene in total cellular DNA of the HPP proposita. The
amplified fragment was subcloned and sequenced. We found a G to A base
substitution in the 22nd codon (CAT for CGT), which changes the normal
arginine to a histidine. Hybridization of amplified DNAs with allele-
specific oligonucleotides corresponding to the normal and mutant sequences
confirmed the presence of the mutation in six other HE and HPP members of
the family. The identification of this mutation at the DNA level confirmed
the transmission of the same molecular defect in Sp through four
generations but with different patterns of clinical expression.
Volume 75,
Issue 8,
pp. 1691-1698,
04/15/1990
Copyright © 1990 by The American Society of Hematology
