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Laboratory parameters provided by Advia 2120 analyser identify structural haemoglobinopathy carriers and discriminate between Hb S trait and Hb C trait
  1. Diego Velasco-Rodríguez1,2,3,
  2. Juan-Manuel Alonso-Domínguez2,
  3. Fernando-Ataúlfo González-Fernández2,4,
  4. Alfonso Muriel1,
  5. Lorena Abalo2,
  6. María Sopeña2,
  7. Jesús Villarrubia1,2,
  8. Paloma Ropero4,
  9. María Paz Plaza1,
  10. María Tenorio1,
  11. Ana Jiménez-Martín1,
  12. Gemma Moreno1,
  13. Jorge Martínez-Nieto4,
  14. Félix de la Fuente-Gonzalo4,
  15. Marina Fernández-Escribano1,
  16. Francisco Javier López-Jiménez1,
  17. Fernando Cava2
  1. 1Hospital Ramón y Cajal, Madrid, Spain
  2. 2Laboratorio Central de la Comunidad de Madrid, Madrid, Spain
  3. 3Programa de Doctorado de Investigación en Ciencias Médico-Quirúrgicas, Universidad Complutense de Madrid, Madrid, Spain
  4. 4Hospital Clínico San Carlos, Madrid, Spain
  1. Correspondence to Diego Velasco-Rodríguez, Department of Hematology, Central Laboratory of Madrid, Hospital Infanta Sofía, Paseo de Europa 34, San Sebastián de los Reyes, Madrid 28702, Spain; diegovelascorodriguez{at}gmail.com

Abstract

Background Haemoglobinopathies have spread owing to human migration, and the number of people needing diagnosis and management of these conditions is increasing. Clinicians need to accurately identify carriers and provide adequate genetic counselling in order to prevent the occurrence of homozygous or compound heterozygous offspring.

Objectives To identify red blood cell (RBC) laboratory parameters that discriminate between structural haemoglobinopathy carriers and healthy subjects, and to compare RBC laboratory indices between HbAS and HbAC individuals.

Methods Samples of 500 variant Hb carriers (355 HbAS, 104 HbAC, 19 HbAD, 7 HbAE, 7 HbAO-Arab, 4 α-chain variants and 4 Hb Lepore) and 251 normal controls were run on an Advia 2120 analyser (Siemens). Classic haematological parameters and RBC populations were assessed in all subjects. A multivariable binary logistic regression model was created to predict the probability of a subject carrying any structural haemoglobinopathy. HbAS (n=355, 71%) and HbAC (n=104, 20.8%) subjects were compared.

Results A clinical prediction rule was developed by assigning one point to each of the most efficient variables: mean corpuscular volume (MCV) <88.4 fL, RBC distribution width >13.4%, percentage of microcytic RBCs (%MICRO) >0.7% and the ratio of microcytic RBCs to hypochromic RBCs >0.8. A score of 0, 1, 2, 3 or 4, resulted in a probability of 9.6%, 36.3%, 66.7%, 85.2% or 98.3%, respectively. Among the most frequent variant Hb, HbAC subjects had lower values of parameters related to cell size (MCV, %MICRO) and higher values of parameters related to haemoglobin concentration (MCHC, %HYPER) than HbAS subjects. Coexistence of α-thalassaemia in both HbAS and HbAC individuals resulted in decreased Hb, MCV, MCH and MCHC.

Conclusions Structural haemoglobinopathy should be investigated in subjects belonging to ethnic groups with high prevalence of variant Hb and with a score of 3 or 4. Erythrocytes of HbAC subjects are smaller and denser than those of HbAS subjects.

  • HAEMATOLOGY
  • HAEMOGLOBINOPATHY
  • AUTOMATED SCREENING

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