Haemostatic Parameters in Patients with Behçet's Disease.

OBJECTIVES: This study aimed to evaluate the cause of thrombosis in Behçet's disease (BD) patients, since abnormalities in coagulation and fibrinolytic parameters have shown contradictory results. METHODS: Haemostatic parameters were retrospectively evaluated in BD patients treated between January 2007 and January 2011 at Sultan Qaboos University Hospital, Oman. The blood samples of 35 Omani BD patients and 30 healthy controls were analysed for factor VIII:C levels, activated protein C resistance (APCR), von Willebrand factor (vWF) antigens (Ag), collagen binding and ristocetin co-factor activity (RiCoF), antithrombin (AT), protein C (chromogenic and clotting), protein S, homocysteine, tissue plasminogen activator, plasminogen activator inhibitor, plasminogen, alpha 2-antiplasmin, lupus anticoagulant and anticardiolipin and beta2-glycoprotein-1 antibodies. RESULTS: The mean values of factor VIII:C, vWF Ag, AT and protein S were significantly higher in the patient group (P = 0.01, 0.006, 0.04 and 0.01, respectively). There was no deficiency in protein C. Screening for APCR, anticardiolipin antibodies, anti-beta2-glycoprotein-1 antibodies and lupus anticoagulant was negative and there were no differences in homocysteine levels, nor were there differences between patients with and without thrombosis. Six patients had elevated factor VIII:C levels (>150 IU/dL, P <0.02) which normalised on repeat measurements after three months. CONCLUSION: The elevation of factors VIII:C, vWF Ag and AT most likely represent an acute phase phenomenon. In this study, thrombophilic factors did not seem to explain thrombotic tendency. Therefore, further mechanistic studies in a larger group of patients are needed to elucidate the basis for thrombosis in BD. We hypothesise that active BD causes vasculitic endothelial perturbation with dysfunction, leading to the observed increased propensity for thrombosis.

Neonatal Screening: Mean haemoglobin and red cell indices in cord blood from Omani neonates.

OBJECTIVES: The aim of this study was to validate the interpretation of red blood cell indices in complete blood count (CBC) and high performance liquid chromatography (HPLC) results on cord blood samples in consecutive Omani neonates. METHODS: Cord blood samples from 7,837 neonates, were analysed with CBC and HPLC using the ß-thalassaemia short programme. Direct sequencing of abnormal samples with HbS, HbD, HbE and HbC was performed to validate the HPLC results. Additionally, in cases with HbA ß10%, the ß-globin gene was directly sequenced for ß-thalassaemia mutation analysis. RESULTS: Overall, 4,042 subjects (51.58%) had normal HPLC (HbA 22.88±8.03; HbF 77.02±8.04), whereas the presence of Hb Barts in the remaining 3,795 cases (48.42%) indicated the presence of α-thalassaemia. No case of HbH was detected. In the former subgroup respectively, the mean Hb (15.38±2.04 g/dl) red blood cell (RBC) count (4.69±0.68 × 10(12)/l), Hct (50.5±7.18%), mean corpuscular volume (MCV) (107.66±7.75 fl), mean corpuscular haemoglobin (MCH) (33.31±4.07 pg), mean corpuscular haemoglobin concentration (MCHC) (30.98±3.44 g/dl), red cell distribution width (RDW) (17.01±2.17%) whereas, in the latter group with α-thalassaemia, it was (14.79±2.90 g/dl); (5.09±0.77 × 10(12)/l); (49.7±7.40%); (97.29±13.8 fl); (29.74±11.80 pg); (30.39±3.6 g/dl), and (18.09±2.56%) respectively. DNA sequencing of samples with abnormal haemoglobin could validate the CBC and HLPC interpretations in all cases. CONCLUSION: This is the first study comparing the hemoglobin and red cell indices in the cord blood from newborn Omani subjects with those from other countries in the region, showing comparable results to those seen in Saudi neonates. The study also validates the CBC and HPLC interpretations of the cord blood red cell indices in the Omani neonate. The incidence of α-thalassaemia diagnosed by the presence of Hb Barts in cord blood of neonates was 48.42%.

Hb Sheffield [ß58(E2)Pro→His] in Oman: potential pitfall in genetic counseling.

A novel ß-globin structural variant, namely Hb Sheffield [ß58(E2)Pro→His], was recently found as a sporadic event in a British Subject and posted to the HbVar database (ID 2672). Here we describe the same variant in 11 Omani subjects in the heterozygous state and in one Omani woman in compound heterozygosity with Hb S [ß6(A3)Glu→Val]. Hb Sheffield coelutes in the Hb A(2) window in the high performance liquid chromatography (HPLC) system as does Hb E [ß26(B8)Glu→Lys], and might be erroneously diagnosed as Hb E unless additional tests including DNA analyses are done. Indeed, correct diagnosis of Hb E is important because of its association with other ß-thalassemic and variant alleles can result in relevant clinical conditions, while Hb Sheffield will not. In a genetic (premarital) counseling setting, and in regions where both Hb E ad Hb Sheffield are present, failure to distinguish these variants will represent a serious pitfall.

Hb A2' (Hb B2) in the Omani population and diagnostic significance.

Hb A(2)' [δ16(A13)Gly→Arg], also called Hb B2, is a δ-globin chain variant that has been identified in several populations of African origin or ancestry and is easily identifiable in alkaline acetate cellulose electrophoresis as doubling of the Hb A(2) band. However, in high performance liquid chromatography (HPLC), commonly employed nowadays, it elutes in the S window. Over a period of 2 years at the Sultan Qaboos University Hospital, Muscat, Oman, we identified 25 Omanis with this variant. The quantity of Hb A(2) ranged from 0.9 to 1.8% in heterozygotes and was undetectable in the single homozygous case. As both α- and ß-thalassemia (α- and ß-thal) as well as Hb S [ß6(A3)Glu→Val] are common in the Omani population, it is important to be aware of the presence of Hb A(2)' in this population to avoid misinterpretation of the HPLC data in terms of underdiagnosis of ß-thal carriers and overestimation of α-thal based on Hb A(2) levels in sickle cell carriers. The haplotype associated with Hb A(2)' in Oman is identical to that described in African populations, suggesting a common origin for this mutation and its introduction into Oman by gene flow.

Forecasting hemoglobinopathy burden through neonatal screening in Omani neonates.

To evaluate the incidence of hemoglobinopathies in Omani subjects and to forecast its future burden on health resources, we initiated a prospective neonatal screening program in two major cities of the Sultanate of Oman. Consecutive cord blood samples from a total of 7,837 neonates were analyzed for complete blood counts and for hemoglobin (Hb) profile by high performance liquid chromatography (HPLC). No case with Hb H (beta4) was detected. We observed that the overall incidence of alpha-thalassemia (alpha-thal) was 48.5% [based on the presence of Hb Bart's (gamma4)] and the beta-globin-related abnormalities accounted for 9.5% of the samples (4.8% sickle cell trait, 2.6% beta-thal trait, 0.9% Hb E trait, 0.8% Hb D trait, 0.08% Hb C trait, 0.3% sickle cell disease and 0.08% homozygous beta-thal). This is also the first large study to establish reference ranges of cord red blood cell (RBC) indices for Omani neonates.

Hereditary thrombophilia in ethnic Omani patients.

Hereditary thrombophilias are a group of inherited conditions that predispose to thrombosis. Mutations like factor V Leiden, prothrombin gene variant 20210A, and hereditary hyperhomocysteinemia are associated with an increased risk for thromboembolism as compared to mutations in natural inhibitors of coagulation. There is also evidence that multiple defects co-exists in persons with a tendency for thrombosis. We studied prothrombotic determinants, namely protein C, protein S, and AT along with factor V Leiden (1691G-->A), prothrombin gene mutation (20210G-->A), CBS 844ins68 mutation, and MTHFR mutation (677C-->T) in consecutive ethnic Omani patients with first episode of a thrombophilic event, namely, deep vein thrombosis (DVT), and/or pulmonary embolism (PE) or thrombosis at an unusual site. Fasting plasma homocysteine was also analyzed. Factor V Leiden and the prothrombin gene mutation were not seen in any patient nor in any control subject studied. The thermolabile MTHFR mutation (677C-->T) was present in 14 patients (35.89%) whereas the CBS 844ins68 mutation was documented in 6 patients (15.38%); 3 patients were common in both groups. Six patients had low protein C (15.38%), two patients had low protein S (5.12%), but none had low AT levels. Interestingly, one patient had triple abnormality, namely, PC deficiency with both CBS 844ins68 mutation as well as the MTHFR mutation (677C-->T) whereas another two patients had the latter two mutations together. This data set, although small, reflects the importance of multiple screening strategies. The yield appears high, emphasizing the referral pattern to a tertiary health center. Of these patients, 43.58% had either or both the hyperhomocysteinemic mutations studied, whereas in 38.46% of these patients, no underlying cause for thrombophilia could be documented.