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This report represents an attempt to define the rate of beta-spectrin de novo mutations affecting mRNA accumulation in patients with hereditary spherocytosis (HS). 19 HS children with haematologically normal parents and varying degrees of spectrin deficiency were studied. 13 of the 19 cases who were heterozygous at the genomic level for polymorphisms in the beta-spectrin coding region were further studied. However, in an analysis of reverse-transcripted amplified cDNA from the regions of the polymorphisms, seven patients appeared to be homozygous, suggesting the occurrence of de novo mutational events affecting expression of one beta-spectrin allele. We conclude that in HS patients with isolated spectrin reduction and normal parents the apparently recessive pattern of inheritance may frequently be associated with de novo monoallelic expression of beta-spectrin.

We report three novel variants of band 3 associated with hereditary spherocytosis: band 3 Foggia (311delC; ACCCAC-->ACCAC), band 3 Napoli I (447insT; TCT-->TTCT) and band 3 Napoli II (1783N; ATC-->AAC). The first two mutations resulted in premature termination of translation, making one haploid set of band 3 mRNA unavailable. Since it affected a highly conserved position at the terminal end of transmembrane domain 11, the third mutation prevented one haploid set of band 3 from becoming incorporated or stabilized into the membrane. These three mutations resulted in a reduction of the band 3 level in the red cell membrane (by 20-25%) and were dominantly transmitted. The D38A substitution (GAC-->GCC) is a low frequency change of band 3. In one compound heterozygote D38A/Napoli II, a markedly aggravated picture required early splenectomy. In contrast, the D38A change was not associated with deterioration in another compound heterozygote, carrying in trans, the previously recorded R760W mutation (CGG-->TGG). In the aggravated case, SSCP analysis did not exhibit any additional change in the two EPB3 alleles. Nor did it show any alteration in the exons of the two ANK1 alleles, and the aggravating factor remained elusive. The D38A alteration should be regarded as an innocuous polymorphism.

We describe a white Italian kindred in which hereditary elliptocytosis (HE) is associated with abnormal level of alpha I/78 peptide in spectrin digest. Clinical phenotype varied among the family members ranging from asymptomatic to mild haemolytic HE. The original mutation responsible is a G-C substitution of the spectrin alpha-gene: alpha 45 Arg-->Thr (AGG-->ACG). The corresponding spectrin is designated spectrin Anastasia. Utilizing a secondary structure predictive method we suggest that this mutation has a poor capability to induce conformational changes of the tetramerization site and thus shows a moderate elliptocytogenic potential.

We describe three Italian subjects from two unrelated families affected with isolated hereditary spherocytosis (HS) without other clinical abnormalities, associated with partial spectrin and ankyrin deficiency. In both families the propositus has normal biological parents, and thus appears to be the result of a new mutation; in one of them the disease is further transmitted in an autosomal dominant fashion. Cytogenetic analysis of the latter family excluded abnormalities of the short arm of chromosome 8. We speculate that in both kindreds ankyrin deficiency is the primary defect related to ankyrin gene mutation. Several pieces of evidence suggest that ankyrin deficiency is probably the most common molecular defect in HS. It is inherited in a, dominant manner and its clinical and biochemical expression is heterogenous.

Glucose-6-phosphate dehydrogenase (G6PD, D-glucose 6-phosphate: NADP oxidoreductase, E.C. 1.1.1.49) activity and the percentage of G6PD deficient erythrocytes was determined in 50 girls heterozygous for G6PD deficiency, 25 of whom had had hyperbilirubinaemia at birth and 25 who had normal bilirubin levels. The enzymatic activity was 2.32 +/- 0.87 I.U./g Hb in the first group and 3.31 +/- 0.92 I.U./g Hb in the second group. The percentage of G6PD deficient erythrocytes was 54.1 +/- 15.3 and 65.3 +/- 14.0, respectively. The level of enzymatic activity exceeded 4 I.U./g Hb and the percentage of G6PD deficient cells fell below 40% in only one of the subjects who had developed hyperbilirubinaemia. Levels of enzymatic activity below 4 I.U./g Hb, or percentages of G6PD deficient erythrocytes higher than 40% can therefore be considered to be associated with a high risk of developing neonatal hyperbilirubinaemia. In our opinion, these babies should receive prophylactic treatment with phenobarbital, as do G6PD deficient Mediterranean males.