Hereditary spherocytosis (HS): Relationship between clinical outcome, diagnostic tests results and membrane protein deficiency a prospective study from Argentina

CRISP RENÉE; SOLARI, L; CHAMORRO MARÍA EUGENIA; GAMMELA D; VOTA DAIANA; GARCÍA, E; VENEGAS, B; MIGUEZ G; SCHVARTZMAN G; RICCHIERI C; ALFONSO G; NESSE, ALCIRA; DONATO, H

Barcelona

Congreso; 15th Congress of the European Hematology Association; 2010

European Hematology Association

Background: HS may be difficult to diagnose because no positive family history is evident in around 25% of patients and accuracy of diagnostic tests is variable No predictive factor for HS outcome based on laboratory tests results is clearly established. Previous large trials simultaneously performing osmotic fragility (OF), autohemolysis (AH), hypertonic cryohemolysis (CH), eosin-5’-maleimide flow cytometry (EMA-FC), and SDS-PAGE analysis of membrane proteins have not been reported. Prevalence of each protein deficiency in Argentine patients is unknown. Aims: a) Assessing relationship between membrane protein defects, laboratory features and clinical outcome; b) Evaluating usefulness of CH and EMA-FC; c) Determining prevalence of protein deficiencies. No previous report concerning these subjects has been published in Argentina. Methods: 106 individuals (60 patients and 46 asymptomatic relatives), aged 1m-77y, belonging to 46 families were prospectively studied; 9 patients had been previously splenectomized; 42 cases were <18y; 255 healthy blood donors served as controls. Following tests were performed: OF, AH, CH, EMA-FC, and SDS-PAGE. Blood samples were collected simultaneously with samples from 6 normal controls and processed within 48 hours. EMA-FC results were expressed as percentage of decrease of mean channel fluorescence (MCF) and as increase of the coefficient of variation (CV). Diagnostic criteria for HS were evidence of hemolytic anemia plus two positive tests. In non-splenectomized patients, anemia was defined as severe, moderate or mild (hemoglobin <8, 8-10 or >10 g/dL, respectively). Relatives showing any membrane protein deficiency but otherwise asymptomatic with negative diagnostic tests were considered as HS silent carriers. Results: HS was diagnosed in 47 patients and 7 relatives; 16 carriers were detected. Inheritance pattern was dominant in 31, nondominant in 14 and undetermined in 9 cases. Anemia was severe in 9, moderate in 13, and mild in 23 non-splenectomized patients. Percentages of positive tests were: EMA-FC 81.5%, CH 81.1%, OF 76.1%, SDS-PAGE 72.7%, and AH 65.9%. Only 19 patients (35.2%) were positive for all the tests. Regarding only CH and EMA-FC, at least one of them was positive in 92.6% of patients. SDS-PAGE showed single or combined protein deficiencies in 48 cases belonging to 27 families. Most frequently found deficiencies were spectrin in analysis by individuals (28.3%) and ankyrin in analysis by families (31.7%). All spectrin-deficient cases showed dominant inheritance. No significant relationship between tests results, inheritance pattern, neonatal jaundice or deficient protein was observed. Analysis of tests in relation to anemia only showed significantly higher increases of CV in moderate and severe anemia than in mild anemia or splenectomized patients (p: 0.004); a trend to significantly lower values of MCF in severe anemia than in other groups was also observed. No relationship between protein deficiencies and severity of anemia was found. Conclusions: A) EMA-FC seems to be a reliable predictor of severity; no other relationship between tests results and outcome was observed. B) Accuracy of EMA-FC and CH for diagnosis was higher than for other tests; simultaneous reading of MCF and CV improves EMA-FC diagnostic usefulness. C) Predominant spectrin and ankyrin deficiencies agree with reports from other Latin American countries