RESUMO
Normal haemoglobin is a tetramer molecule, consisting of two α and ß haemoglobin chains. Haemoglobinopathies occur when abnormalities in these proteins are present. More than 1000 naturally occurring human haemoglobin variants with single amino acid substitution throughout the molecule have been identified and can be discovered through their clinical and biological manifestations. Here, we report the case of a 60-year-old woman for whom no oximetry results were obtained during blood gas analysis (BGA) and the values of oxygen saturation obtained from pulse oximetry (73%) and co-oximetry (90%) differed. Haemoglobin analysis demonstrated the presence of a variant in the alpha chain. Clinical history of the patient and her family revealed they carry a haemoglobin variant (Titusville type), thus representing the first French family case reported. Those results raised the question whether the presence of this variant could be the cause of the errors encountered during BGA.