Atypical Sickle Cell Syndromes: A Report On Two Cases

Sickle cell syndromes are generally the consequence of the homozygous sickle mutation or associated in trans with another haemoglobin variant or beta-thalassaemia. We present two cases of atypical sickle cell syndrome identified among sickle cell disease children diagnosed at the Pediatric Hospital Robert-Debre, Paris, and Louis-Mourier Hospital, Colombes, France. The first case is a 9-year-old girl who is a compound heterozygote S/C-Ndjamena. She carries the PS mutation (HBB:c.20A > T[p.Glu6Val]) on one allele and the PS mutation together with a beta(37) (HBB:c.112T > G[p.Trp37Gly]) mutation in cis on the other allele. This second mutation is responsible of an increased affinity of haemoglobin for oxygen explaining the reduced symptomatology of this child who is homozygous for the 135 mutation. The second case is S/beta(+)-thalassaemia with high expression of HbA and without clinical symptomatology. The child was carrier for the -101C > T mutation (HBB:c.-151C > T) located in the most distal CACCC box of the p-globin gene promotor, mutation known to be responsible of silent beta-thalassemia in heterozygotes. The phenotype is similar to that of an A/S subject. Familial phenotypical and genotypical studies are essential in similar cases to make a correct diagnosis that explains the patients' symptomatology of and also to detect rare haemoglobin variants, which associated to sickle cell anaemia, influence the symptomatology. (C) 2011 Elsevier Masson SAS. All rights reserved.