Search

High oxygen affinity hemoglobin (HOAH) is the main cause of constitutional erythrocytosis. Mutations in the genes coding the alpha and beta globin chains ( HBA1 , HBA2 and HBB ) strengthen the binding of oxygen to hemoglobin (Hb), bringing about tissue hypoxia and a secondary erythrocytosis. The diagnosis of HOAH is based upon the identification of a mutation in HBA1 , HBA2 or HBB in specialized laboratories. Phenotypic studies of Hb are also useful, but electrophoretic analysis can be normal in 1/3 of cases. The establishment of the dissociation curve of Hb can be used as another screening test, a shift to the left indicating an increased affinity for Hb. The direct measurement of venous P50 using a Hemox Analyzer is of great importance, but due to specific analytic conditions, it is only available in a few specialized laboratories. Alternatively, an estimated measurement of the P50 can be obtained in most of the blood gas analyzers on venous blood. The aim of our study was therefore to determine whether a normal venous P50 value could rule out HOAH. We sequenced the HBB , HBA1 and HBA2 genes of 75 patients with idiopathic erythrocytosis. Patients had previously undergone an exhaustive medical check-up after which the venous P50 value was defined as normal. Surprisingly, sequencing detected HOAH in three patients (Hb Olympia in two patients, and Hb St Nazaire in another). A careful retrospective examination of their medical files revealed that (i) one of the P50 samples was arterial; (ii) there was some air in another sample; and (iii) the P50 measurement was not actually done in one of the patients. Our study shows that in real life conditions, due to pre-analytical contingencies, a venous P50 value that is classified as being normal may not be sufficient to rule out a diagnosis of HOAH. Therefore, we recommend the systematic sequencing of the HBB , HBA1 and HBA2 genes in the exploration of idiopathic erythrocytosis.

: Congenital factor X deficiency is a rare coagulation defect characterized by variable bleeding tendency. The aim of the study was to give a first insight of F10 gene mutations in Pakistani probands. Direct sequencing and/or next-generation sequencing was performed on the coding regions, boundaries and 5' and 3' untranslated regions of the F10 gene in five severe factor X-deficient patients from Pakistan. All patients were born from consanguineous marriages and displayed FX:C levels below 2%. Sequencing revealed five different substitutions, including three previously reported p.Ala15Asp, p.Gly406Ser, and p.Gly420Arg missense variants, and also two novel variants: p.Cys57Arg and p.Gln175*. Though one genotype could not be characterized, we were able to confirm the inherited nature of the defect using familial studies. As the copy number variations were ruled out, we hypothesized the presence of deep intronic mutants that might have escaped detection from sequencing or abnormalities in epigenetic regulation. Three patients presented with severe clinical symptoms, in the early days of life, whereas two presented only with trauma-provoked bleeds and bruises later in life. Those patients with milder forms bore the p.Gly406Ser at the homozygous state and F10 unknown alleles, respectively. F10 mutation spectrum in Pakistan is heterogeneous as seen in other populations. Identification of the F10 mutations is important for genetic counseling and prenatal diagnosis in subsequent pregnancies.

Hereditary factor VII (FVII) deficiency is a rare autosomal recessive disorder. Deleterious mutations that prevent the synthesis of any amount of functional FVII have been associated with life-threatening haemorrhage in neonates. Here we report two infants, of Maghrebian origin, who suffered a fatal spontaneous cerebral haemorrhage. Investigation of the molecular basis for their severe FVII deficiency revealed novel mutations in a homozygous state within the F7 gene promoter: a single nucleotide substitution (c.-65G>C) and a 2bp deletion (c.-60_-59delTT). To determine whether these promoter variants were responsible for the FVII deficiency, computer-assisted sequence analyses were performed. The data predicted a disrupted binding of both HNF4 and COUP-TF transcription factors with each variant. Concordantly, experimental results revealed an altered HNF4-induced transactivation in the promoter mutated variants. The execution of functional tests is critical to ensuring a complete understanding of the effect of any promoter mutant on FVII deficiency. Only then can an accurate molecular diagnosis be made and further genetic counselling and prenatal diagnosis be offered.

We describe a family with beta-thalassemia in which several pitfalls of genetic diagnoses were present. These include coherent family phenotypes with discrepancies in molecular findings because of nonpaternity, and a false beta-globin gene homozygous genotype due to a large deletion in the second locus. These findings underline the difficulties of family genetic studies and the need for tight relationship between professionals involved in laboratory studies and those in-charge of the clinical follow-up and genetic counselling. In this family, we also report a new silent beta-thalassemia mutation, -102 (C>A), in the distal CACCC box of the beta-globin gene promoter.

The article focuses on importance of prenatal diagnosis and primary prophylaxis in preventing Congenital factor VII (FVII) autosomal recessive haemorrhagic disorder. It states that variability exists in Clinical phenotypes of FVII disorder such as central nervous system (CNS) and/or gastrointestinal (GI) tract bleeding and mentions that in prenatal diagnosis of FVII disorder, amniocentesis is performed between 16 and 19 weeks of pregnancy.