Expression of spectrin alphaI/50 hereditary elliptocytosis and its association with the alphaLELY allele.

Hereditary elliptocytosis (HE) is a group of hemolytic anemias characterized by the presence of elliptical erythrocytes. The underlying alterations lie in the proteins of the membrane skeleton. Defects of the alphaI domain of spectrin have been defined based on a decrease in the normal 80-kD alphaI domain and a concomitant increase in one or more lower molecular weight peptides. We have studied three Brazilian kindreds with black ancestry, who presented mild common spalphaI/50 HE. Our aim was to determine the molecular alteration responsible for the spalphaI/50 HE observed in these three kindreds and to evaluate the presence and influence of allele alphaLELY in the expression of this type of HE. In order to establish the molecular defect, exons 5, 6 and 11 were amplified and submitted to a nonradioactive single strand conformation polymorphism protocol. An identical band shift in exon 6 was observed in all 3 patients and their affected relatives. Direct sequencing of the amplification products of exon 6 showed the same molecular defect in all patients: a T-->C substitution, responsible for the L260P mutation. Allele alphaLELY, detected by PCR and restriction enzyme digestion, was present in the heterozygous form in the three propositi and was associated in trans with the elliptocytogenic mutation. Blood smears of the patients with HE and alphaLELY in trans showed pronounced elliptocytosis, poikilocytosis and a few small red cell fragments, whereas the blood smears of their relatives, who had HE without allele alphaLELY, showed mild common HE with a predominance of ovalocytes and the absence of poikilocytes. We conclude that allele alphaLELY does not lead to the worsening of clinical conditions when associated in trans with mild HE, but can be easily distinguished by a blood smear analysis. The predominance of the L260P mutation in the kindreds studied could be related to the colonization of Brazil during the slave trade by Africans from the Benin-Togo area, where this mutation is particularly common.

Beta-spectrin Campinas: a novel shortened beta-chain variant associated with skipping of exon 30 and hereditary elliptocytosis.

Beta-Spectrin Campinas is a novel spectrin variant associated with a shortened beta-chain in a kindred with hereditary elliptocytosis (HE). The propositus and her mother exhibited increased amounts of spectrin dimers and an increase in the alphaI 74 kD fragment from the alpha-chain after partial tryptic digestion of spectrin. The shortened beta-chain appeared as an additional band of approximately 200 kD on SDS-PAGE. In order to delineate the molecular defect of this abnormality at the gene level, reticulocyte mRNA was transcribed into cDNA and the last four exons of the beta-spectrin gene were amplified. Agarose gel of the amplification product of the propositus revealed the expected band of 487 bp as well as a shortened band of approximately 300 bp (size determined on gel). This shortened cDNA amplification product was cloned and nucleotide sequencing revealed the absence of the entire exon 30. In order to determine the underlying mutation responsible for this abnormal splicing, a genomic DNA fragment containing exons 30 and 31 was amplified and nucleotide sequencing revealed a G-->A substitution at the 5' donor splice site consensus sequence of intron 30 (nt + 1 IVS30). The skip splicing observed in this study results in a frameshift, creating a new stop codon and causing a deletion of 129 amino acids at the very COOH-terminus of the protein, thus impairing spectrin dimers self-association. We classified this HE as spherocytic HE because the propositus presented a few spherocytes in addition to many elliptocytes in the blood smear, whereas her mother, who was splenectomized, showed many schizocytes, poikilocytes and spherocytes.

Expression of spectrin alpha I/65 hereditary elliptocytosis in patients from Brazil.

We report the clinical and laboratory findings in three unrelated families from southeastern Brazil with Sp alpha I/65 hereditary elliptocytosis (HE), including one homozygote and a patient presenting an elongated beta-spectrin. In family 1, three patients presented the allele alpha-Lely in trans to the elliptocytogenic allele. In these three patients the blood smear showed pronounced elliptocytosis, poikilocytosis and a few small red cell fragments instead of the mild elliptocytosis observed in their father, who did not present the polymorphism. In family 2 we describe one homozygote, with consanguineous parents presenting with anaemia, splenomegaly, severe poikilocytosis and elliptocytosis, budding, microspherocytes and numerous fragments in the blood smear. In family 3 we found an elongated beta Sp in a patient with Sp alpha I/65. The cause of the HE was the Sp alpha I/65 since the elongated beta Sp was not found in his brother, who also presented with HE and Sp alpha I/65. Apparently the abnormal beta Sp did not aggravate the HE, because both individuals had the same clinical and laboratory findings. However, the propositus presented a few more elliptocytes and poikilocytes than his brother, probably because the elongated beta-spectrin may have disturbed the spectrin self-association. In fact, in the propositus an abnormal band was observed in the nondenaturing gels, just above the Sp dimer, probably as a result of the association of the abnormal beta Sp with the normal spectrin chains. In the family studied here, both brothers presented the allele alpha Lely, but as their mother was dead, it was not possible to determine the polymorphism transmission. However, the high number of poikilocytes observed in the blood smear of both cases suggests an association in trans with the Sp alpha I/65. Thus, taken together, the data in this report indicate that HE secondary to Sp alpha I/65 abnormality is frequent in Brazil, and in one case it was associated with an apparently novel abnormal large beta-spectrin.

Red cell membrane protein abnormalities in hereditary spherocytosis in Brazil.

We studied 14 kindred and nine unrelated patients from southeastern Brazil with the typical form of hereditary spherocytosis. Diagnosis was made on the basis of clinical features, presence of spherocytes on the peripheral blood smears and an abnormal osmotic fragility test. By densitometric tracing of SDS-PAGE stained by Coomassie blue, we detected isolated deficiency of spectrin in 39% of our patients, combined spectrin and ankyrin deficiency in 13%, and deficiency of band 3 in 13%. One of our patients presented ankyrin deficiency without spectrin reduction. Our data suggest that, despite ethnic differences among the Brazilian and European or North-American populations, these biochemical abnormalities in HS patients may be similar.