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.

First reported case of compound heterozygosity for HbA2-Yialousa (HBD: c.82 G>C) and HbA2-Wrens (HBD: c.295 G>A) in Oman.

We report the presence of two different dglobin gene mutations causing d?-thalassemia in association with homozygous (-a3.7/-a3.7) genotype for the first time in an Omani child with a low hemoglobin A2 (HbA2) of 0.8 %. Direct nucleotide sequencing revealed compound heterozygote mutations in the patient's d-globin genes: HbA2-Yialousa (HBD: c.82G[C) and HbA2- Wrens (HBD: c.295G[A). In Oman, where a and b-thalassemia and HbS are prevalent, an awareness of the presence of different d-globin gene mutations is important as complex interactions between these hemoglobinopathies can lead to the misdiagnosis of b-thalassemia carriers.

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%.

Protein Z levels in pregnant Omani women: correlation with pregnancy outcome.

Placental insufficiency resulting in fetal loss has been recognized in women with thrombophilic predisposition. Recent studies indicate that there is a high prevalence of protein Z (PZ) deficiency in patients with unexplained fetal loss. The objective of this study was to measure the PZ levels in pregnant Omani women in the first, second and third trimesters and correlate with the pregnancy outcome. The study enrolled 126 consecutive pregnant women after an informed consent prospectively. PZ was estimated in the first, second and third trimester in 15, 97 and 66 pregnant women respectively and they were followed for pregnancy outcomes including live birth, still birth, spontaneous abortion/induced abortion, maternal complications, fetal complications and health risks/complications in the newborn. The median PZ level (Mean ± SD) in the first, second and third trimester were 0.98 (1.07 ± 0.46), 1.3 (1.36 ± 0.61) and 1.44 (1.43 ± 0.69) (P < 0.05, Student's t-test, between first vs. second and first vs. third trimester). PZ deficiency defined as PZ level below 0.54 µg/ml (below 10th centile in the Omani population) was observed in 4 (4.7%) women, but interestingly all had a normal pregnancy outcome. Amongst the 43 subjects in whom paired PZ estimations were available, reducing PZ levels were observed from baseline values in 8 (33%) with normal pregnancy outcome; 5 (55%), with diabetes; 3 (50%) with hypertension and 2 (50%) with low birth weight respectively (P < 0.05, chi square test). PZ values increased progressively during the three trimesters of pregnancy. However, this increase is blunted in patients with abnormal pregnancy outcome like low birth weight babies or pregnancies associated hypertension or diabetes. Isolated PZ deficiency alone did not result in an abnormal outcome in this cohort of subjects.

The ß-globin promoter -71 C>T mutation is a ß+ thalassemic allele.

A novel ß-globin gene promoter (-71 C>T) nucleotide change was recently posted to the HbVar database (ID 2701) without precision on phenotype and ethnicity. We found the same change in compound heterozygosity with Hb S [ß6(A3)Glu>Val] in an Omani family with almost equal expression of Hb A and Hb S. This suggested that the -71 C to T mutation may be a mild ß-thalassemic allele. Subsequent search found three other independent cases with the same atypical Hb A:Hb S ratio, further confirming the mild thalassemic feature of this mutation. In addition, molecular screening of a set of subjects (with only Hb A) with borderline Hb A(2) or MCV values revealed the presence of -71 C>T change in heterozygous state, altogether assigning the mutation as a mild ß(+) thalassemic allele. In a region such as Oman, where several genetic conditions of the red blood cell coexist (α- and ß-thalassemia, Hb S, Hb D, Hb E) in significant frequencies, it is crucial to decipher the molecular basis of these atypical forms of ß(+) thalassemias, especially in a genetic counseling setting.

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.

Haematological and clinical features of beta-thalassaemia associated with Hb Dhofar.

Hb Dhofar is a variant haemoglobin (beta(29 (GGC-GGT) gly-gly), beta(58 (CCT-CGT) pro-arg)) associated with a thalassaemic phenotype and unique to the Sultanate of Oman. We report clinical and haematological data on 54 subjects with Hb Dhofar (37 heterozygotes, 14 homozygotes and three compound heterozygotes with a different beta-thalassaemia mutation). In heterozygotes, the level of Hb Dhofar ranged from 8.8% to 21.5%. All heterozygotes had Hb A2 > 3.5%, consistent with beta-thalassaemia trait. Hb Dhofar in homozygotes and compound heterozygotes ranged from 26% to 59.7%, with a peripheral film consistent with homozygous beta-thalassaemia. Age at presentation in homozygotes ranged between 6 months and 8 yr, with a majority presenting before 5 yr of age. All had splenomegaly and six (43%) had undergone splenectomy. All had some degree of frontal bossing and in particular, two patients with infrequent transfusions had marked thalassaemic facies and stunting of growth. Hb Dhofar can be mistaken for Hb D as the electrophoretic mobility is similar, but differs from it by a variable and reduced quantity of variant Hb in both heterozygotes and homozygotes. Clinical and haematological data suggest that this mutation behaves like a moderately severe beta(+) thalassaemia allele resulting in a thalassaemia intermedia phenotype.

Serum transferrin receptor status of healthy adult Arabs.

Several studies have provided reference ranges for the concentration of serum transferrin receptor (sTfR) in various white populations, but there is a dearth of relevant reference sTfR data in non-whites. The aim of this investigation was to establish sTfR reference ranges and mean values for a healthy non-white Arab population that could be used also for Arabs worldwide. sTfR and serum ferritin concentrations were estimated by immunoassays and blood counts were determined by conventional methods. Analysis of the data of 114 volunteer Arab blood donors (91 male, 23 female) revealed a higher mean sTfR concentration in males of 22.6+/-8.1 nmol/L (range 10.9-38.7 nmol/L) compared to that in females of 18.7+/-4.4 nmol/L (range 10.7-25.8 nmol/L, p=0.001). There was no significant correlation of sTfR concentration with age, serum ferritin level, or blood haemoglobin level, but a strong inverse correlation was demonstrated with mean cell volume and mean cell haemoglobin of red cells. Iron-replete volunteer subjects with alpha-thalassaemia trait appear to have relatively high mean sTfR concentration. We recommend the use of gender-dependent sTfR reference values for Arabs.

Diagnosis of Beta-thalassaemia carriers in the sultanate of oman.

BACKGROUND: Haemoglobinopathies are a major cause of morbidity in the Sultanate of Oman and premarital screening is being encouraged in order to reduce the number of affected births. The identification of ß-thalassaemia carrier status is an essential prerequisite of any screening programme. However, the level of Haemoglobin (Hb) A(2), which is used to detect ß-thalassaemia carriers, can be affected by other factors including iron deficiency, concurrent α thalassaemia and the type of DNA mutation present. OBJECTIVES: The following study was undertaken to ascertain if the Hb A(2) level is an appropriate tool for the identification of ß-thalassaemia carriers in the Omani population. METHOD: Hb A(2) was measured by high performance liquid chromatography (HPLC) in 160 obligate carriers of ß-thalassaemia. 158 subjects had Hb A(2) levels above 3.5% indicating ß-thalassaemia trait. Two subjects had slightly lower levels and were found to be iron deficient. After therapy both these subjects' Hb A(2) levels increased to above 3.5%. CONCLUSION: In the absence of iron deficiency, Hb A(2) is an accurate marker for the presence of ß-thalassaemia trait in the Sultanate of Oman.