Reliable assessment of the incidence of childhood autoimmune hemolytic anemia.

BACKGROUND: Childhood autoimmune hemolytic anemia (AIHA) is a rare and severe disease characterized by hemolysis and positive direct antiglobulin test (DAT). Few epidemiologic indicators are available for the pediatric population. The objective of our study was to reliably estimate the number of AIHA cases in the French Aquitaine region and the incidence of AIHA in patients under 18 years old. PROCEDURE: In this retrospective study, the capture-recapture method and log-linear model were used for the period 2000-2008 in the Aquitaine region from the following three data sources for the diagnosis of AIHA: the OBS'CEREVANCE database cohort, positive DAT collected from the regional blood bank database, and the French medico-economic information system. RESULTS: A list of 281 different patients was obtained after cross-matching the three databases; 44 AIHA cases were identified in the period 2000-2008; and the total number of cases was estimated to be 48 (95% confidence interval [CI]: 45-55). The calculated incidence of the disease was 0.81/100,000 children under 18 years old per year (95% CI 0.76-0.92). CONCLUSION: Accurate methods are required for estimating the incidence of AIHA in children. Capture-recapture analysis corrects underreporting and provides optimal completeness. This study highlights a possible under diagnosis of this potentially severe disease in various pediatric settings. AIHA incidence may now be compared with the incidences of other hematological diseases and used for clinical or research purposes.

Severe delayed autoimmune haemolytic anaemia following artesunate administration in severe malaria: a case report.

BACKGROUND: Parenteral artesunate is recommended as first-line therapy for severe and complicated malaria. Although its efficacy has been proven, long-term safety profile is still under evaluation. Several cases of delayed haemolytic anaemia occurred after initial clinical improvement and resolution of parasitaemia in non-immune travellers and children living in endemic areas. Reports have generated concern that this phenomenon might be related to the treatment itself, either by direct toxicity or immune-related mechanism. This is a report of the first case of autoimmune haemolytic anaemia following treatment of severe malaria initially managed with parenteral artesunate with strong indication for drug-immune related mechanism. CASE: A 17-year old Ivoirian female travelling in France presented with fever, headache and abdominal pain seven days after her arrival. Physical examination was indicative of septic shock while blood analysis showed normal haemoglobin level, but profound thrombocytopaenia and hyperlactataemia. Blood smear analysis showed Plasmodium falciparum infection with a parasitaemia of 0.8%. Severe malaria was diagnosed according to the WHO criteria. The patient was initially managed with artemether/lumefantrine combination and then parenteral artesunate for 48 hours. Empiric antibiotic course was also initiated with ceftriaxone, metronidazole, gentamycin, and then piperacillin and ciprofloxacin. At day 14, haemoglobin dropped to 4.6 g/dL with biologic features indicative of haemolysis (LDH 658 U/L, haptoglobin<0.15 g/L). At that time, parasitaemia was negative and other infections or hereditary disorders were excluded, while Coombs' direct antiglobulin test was positive for IgG and C3d. Antinuclear antibodies were absent. Further investigations evidenced drug-induced antibodies related to artesunate. It was concluded a drug-mediated autoimmune haemolytic anaemia. A corticosteroids regimen was initiated at 1 mg/kg/day. Outcome was favourable and corticosteroids were progressively tapered during two months. At present the patient's condition remains stable without recurrence of haemolytic anaemia. CONCLUSION: This is the first case of delayed haemolytic anaemia related to artesunate with a strong indication for drug-immune related mechanism. Further research is warranted to better characterize this plausible cause of post-treatment haemolysis following parenteral artesunate administration in severe malaria patients.

Characterization of novel RHD alleles: relationship between phenotype, genotype, and trimeric architecture.

BACKGROUND: RH1 is one of the most clinically important blood group antigens in the field of transfusion and prevention of fetomaternal incompatibilities. New variant RHD alleles are regularly identified and their characterization is essential to ensuring patient safety. STUDY DESIGN AND METHODS: Blood samples with uncertain RhD phenotypes not resolved by our first-line SNaPshot assay were sequenced for all 10 RHD exons. RHD zygosity was investigated. Flow cytometry was performed to determine RhD antigen density and epitope pattern. RESULTS: Seven novel RHD alleles were identified. Six, that is, RHD(T55P), RHD(A85G), RHD(G132R), RHD(G132E), RHD(D403V), and DAR(T203A), resulted from nucleotide polymorphisms. The seventh, that is, RHD(S182WfsX46), resulted from a 4-bp deletion that led to a reading frame shift and the appearance of a premature stop codon. Study of RhD expression of the first five alleles at hemizygous state showed greatly reduced antigen densities ranging from 50 to 618 antigens per red blood cell (RBC). DAR(T203A) was classified as a partial D antigen with a weakened reactivity profile similar to that of DAR. As expected, no D antigen was detected on RBCs carrying the RHD(S182WfsX46) allele. In parallel, RhD expression of RHD(G336R)/weak D type 58, RHD(F410V), and suspected RHD(1-9)-CE was determined to be less than or equal to 50 antigens per RBC. RhAG/RhD(2) trimer model supports the observed phenotypes. CONCLUSION: Although the frequency of the new RHD alleles presented herein is low, their phenotypic and genotypic description adds to the repertoire of reported RHD alleles. These data can be useful for optimization of molecular screening tools.

Molecular background of D(C)(e) haplotypes within the white population.

BACKGROUND: D(C)(e) and D(C)e haplotypes may be encountered in the white population. Few data are available on the molecular backgrounds responsible for depressed expression of C and e. STUDY DESIGN AND METHODS: Individuals of white origin carrying a D(C)(e) genotype resulting in depressed expression of C or both C and e were subdivided into two categories based on the RBC reactivity with the human sera Mol and Hor, which contain antibodies against low-frequency antigens of the Rh (RH) system and other non-Rh low-frequency antigens. Neither Hor+, Mol+ nor Hor+, Mol- RBCs expressed the V (RH10), VS (RH20), and/or Rh32 (RH32) low-frequency antigens. These results suggested that Hor+, Mol+ variants expressed Rh33 (RH33 or Har) and FPTT (RH50), whereas Hor+, Mol- variants might express an undefined low-frequency antigen. Further serologic and molecular analyses were performed. RESULTS: Molecular analysis of Hor+, Mol+ variants revealed a hybrid gene structure RHCe-D(5)-Ce, in which exon 5 of RHCE (RHCe allele) was replaced by exon 5 of RHD (the so-called RHCeVA allele). The presence of exon 5RHD resulted in several amino acid alterations predicted in the external loop 4 of the CeVA polypeptide. Molecular analysis of Hor+, Mol- variants revealed the presence of a new RHCe allele characterized by a single point mutation C340T within exon 3 (the so-called RHCeMA allele), resulting in a R114W substitution predicted on the external loop 2 of the CeMA polypeptide. A serologic study showed a different pattern of reactivity with C and e MoAbs. CONCLUSION: Two types of mutations resulted in amino acid substitutions predicted in external loops 4 and 2, respectively, which altered both the C and e reactivity, and indicated conformation changes or defective interaction between nonadjacent loops of the Ce polypeptide. Serologic analysis showed that together with Hor and Mol sera testing, the use of different C and e MoAbs could help to identify these variants within the white population.