dRTA and hemolytic anemia: first detailed description of SLC4A1 A858D mutation in homozygous state.

Mutations in the anion exchanger 1 (AE1) gene encoding the erythroid and kidney anion (chloride-bicarbonate) exchanger 1 may result in familial distal renal tubular acidosis (dRTA) in association with membrane defect hemolytic anemia. Seven children presenting with hyperchloremic normal anion gap metabolic acidosis, failure to thrive, and compensated hemolytic anemia were studied. Analysis of red cell AE1/Band 3 surface expression by Eosin 5'-maleimide (E5M) was performed in patients and their family members using flow cytometry. Genetic studies showed that all patients carried a common SLC4A1 mutation, c.2573C>A; p.Ala858Asp in exon 19, found as homozygous (A858D/A858D) mutation in the patients and heterozygous (A858D/N) in the parents. Analysis by flowcytometry revealed a single uniform fluorescence peak, with the mean channel fluorescence (MCF) markedly reduced in cases with homozygous mutation, along with a left shift of fluorescence signal but was only mildly reduced in the heterozygous state. Red cell morphology showed striking acanthocytosis in the homozygous state [patients] and only a mild acanthocytosis in heterozygous state [parents]. In conclusion, this is the first description of a series of homozygous cases with the A858D mutation. The E5M flowcytometry test is specific for reduction in the Band 3 membrane protein and was useful in conjunction with a careful morphological examination of peripheral blood smears in our patient cohort.

Human platelet alloantigens (HPA) 1, HPA2, HPA3, HPA4, and HPA5 polymorphisms in sickle cell anemia patients with vaso-occlusive crisis.

OBJECTIVES: Vaso-occlusive crisis (VOC) is a significant cause of morbidity and mortality in sickle cell anemia (SCA) patients. Insofar as polymorphism in human platelet alloantigen (HPA) exhibit a prothrombotic nature, we hypothesized that specific HPA polymorphic variants are associated with VOC. We investigated the distribution of HPA1, HPA2, HPA3, HPA4, and HPA5 alleles genotypes among VOC and non-VOC control SCA patients. PATIENTS/METHODS: This was a case-control study. Study subjects comprised SCA patients with (VOC group; n = 127) or without (Steady-state group; n = 130) VOC events. HPA genotyping was done by PCR-SSP. RESULTS: Significantly higher frequencies of HPA-2b, HPA-3b, and HPA-5b alleles, and marked enrichment of HPA-3b/3b, HPA-5a/5b, and HPA-5b/5b genotypes, were seen in VOC than in control SCA patients. Taking homozygous wild-type genotypes as reference, univariate analysis identified HPA-3a/3b, HPA-3b/3b, and HPA-5b/5b to be associated with VOC. Multivariate analysis confirmed the independent association of only HPA-3a/3b and HPA-3b/3b genotypes with VOC. HPA-3 genotypes were significantly correlated with VOC frequency, type, and medication, and requirement for hospitalization. While both HPA 3a/3b (P = 0.002; OR = 2.94; 95% CI = 1.49-5.77) and 3b/3b (P = 0.006; OR = 3.16; 95% CI = 1.40-7.17) genotypes were associated with need for hospitalization, only HPA-3b/3b was associated with VOC frequency, type (localized vs. generalized), and medication (narcotics vs. NSAIDs). CONCLUSION: This confirms the association of HPA polymorphisms with SCA VOC, of which HPA-3 appears to be independent genetic risk factors for SCA VOC.

Gene frequencies of human platelet alloantigens in Bahraini Arabs.

Human platelet antigens (HPA) are implicated in the pathophysiology of certain hematological disorders, and as varied distribution of HPA-1 alleles and genotypes were reported fordifferent countries and ethnic populations, we determined the distribution of HPA-1, -2, -3, -4, and -5 alleles, genotypes and haplotypes for 194 healthy Bahraini subjects by polymerase chain reaction with sequence specific primers. The distribution of the HPA polymorphisms was in Hardy-Weinberg equilibrium. Allele frequencies of 0.76 and 0.24 (HPA-1a and -1b), 0.77 and 0.23 (HPA-2a and -2b), 0.57 and 0.43 (HPA-3a and -3b), 0.93 and 0.07 (HPA-4a and -4b), and 0.86 and 0.13 (HPA-5a and -5b) were seen. With the exception of HPA-3a/a (30.4%), the frequencies of homozygous HPA-1a/a (56.8%), 2a/a (60.1%), 4a/a (87.2%), and 5a/a (75.7%) were higher than those of heterozygous (a/b) or homozygous (b/b) variants. Our results provide basic information for further studies of the HPA system polymorphism, which in turn will be instrumental in understanding and treating immune-mediated platelet disorders.

Association of the methylenetetrahydrofolate reductase A1298C but not the C677T single nucleotide polymorphism with sickle cell disease in Bahrain.

The association of methylenetetrahydrofolate reductase (MTHFR) gene mutations, C677T and A1298C, together with changes in homocysteine (Hcy) levels was investigated in 106 sickle cell disease patients and 156 healthy controls from Bahrain. The mutation analysis was done by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR). While the frequencies of the mutant alleles C677T and A1298C were comparable between patients and controls, the frequency of the A1298C (C/C) (p = 0.03) but not C677T (T/T) (p = 0.67) genotype, and of the 677T/1298C haplotype were significantly higher in the patients (p = 0.05). Homocysteine levels were normal in all subjects. This suggests that the A1298C, but not C677T, mutation is associated with the genotype of sickle cell disease.

Varied prevalence of factor V G1691A (Leiden) and prothrombin G20210A single nucleotide polymorphisms among Arabs.

BACKGROUND: Factor V G1691A (FV-Leiden) and prothrombin (PRT) G20210A single nucleotide polymorphisms (SNPs) are major inherited risk factors of venous thromboembolism. In view of the heterogeneity in their world distribution and lack of sufficient information about their distribution among Arabs, we addressed the prevalence of both SNPs in 4 distinct Arab populations (Lebanon, Tunisia, Bahrain, and Saudi Arabia). METHODS: Study subjects comprised 698 Lebanese, 313 Tunisian, 194 Bahraini, and 149 Saudi Arabian healthy subjects; genotyping was done by PCR-RFLP using Mnl I and Hind III for FV-Leiden and PRT G20210A, respectively. RESULTS: The prevalence of the mutant A alleles of FV-Leiden and PRT G20210A were significantly higher among Lebanese (0.0788 and 0.0136) and Tunisians (0.0351 and 0.0128), as compared to Bahraini (0.0155 and 0.0052) and Saudi (0.0101 and 0.000) subjects. Higher frequency of the FV-Leiden G/A and A/A genotypes were seen in Lebanon (13.8 and 1.0%), followed by Tunisia (5.8 and 0.6%), Bahrain (3.1 and 0.0%) and Saudi Arabia ((2.0 and 0.0%). All PRT G20210A positive cases were in the heterozygote (G/A) state, and these comprised 3.6% for Lebanon, 2.6% for Tunisia, 1.0% for Bahrain. The carrier rate of FV-Leiden was significantly higher among Lebanese compared to the other populations (p < 0.001), while the difference in the prevalence of FV-Leiden between the other populations was not statistically different. With the exception of Lebanese-Saudi (p = 0.038), the prevalence of PRT G20210A was similar among the study communities. Furthermore, the overall average genetic differentiation between populations (estimated with the F(ST)) was 0.0022 for FV-Leiden and 0.005 for PRT G20210A. CONCLUSIONS: These results further confirm the heterogeneity in FV-Leiden and PRT G20210A distribution among Arabs, and recommend potential institution of prophylactic measures for carriers of either or both SNPs.

Low prevalence of antibodies to human T-lymphotropic virus-I/II among blood donors in eastern Saudi Arabia.

The seroprevalence of human T-lymphotropic virus (HTLV)-I/II was assessed in 13,443 consecutive blood donors in eastern Saudi Arabia between 1998 and 2001. Screening by enzyme-linked immunosorbent assay (ELISA) and confirmation by Western blot resulted in 8 (0.060%) positive cases, of which 5 (0.056%) belonged to Saudi and 3 (0.113%) to non-Saudi donors. The majority of the HTLV-positive donations (6/8) were for patients, and none had a history of known risk factor for HTLV-I/II transmission. Although the very low prevalence of HTLV-I/II among Saudi donors does not support routine screening, screening of donors from other nationalities may be initiated, especially those from HTLV-I/II endemic areas.

Hepatitis B and hepatitis C virus prevalence among dialysis patients in Bahrain and Saudi Arabia: a survey by serologic and molecular methods.

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections were assessed among 81 Bahraini and 34 Saudi hemodialysis patients and 7714 Bahraini and 2330 Saudi blood donors. Higher prevalence of HCV (9.24% vs 0.30%), hepatitis B surface antigen (5.88% vs 0.62%) were seen in patients versus control patients, and in Saudi patients compared with Bahraini patients. HCV genotypes were HCV 1a/1b plus HCV 4 among Bahraini patients and HCV 2/2a plus HCV 4 among Saudi patients. This is the first report on viral hepatitis in Bahrain and the first to compare HBV/HCV among dialysis patients in the Eastern Arabian Peninsula.

Factor V-Leiden, prothrombin G20210A, and MTHFR C677T mutations among patients with sickle cell disease in Eastern Saudi Arabia.

The prevalence of factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations were investigated among 87 Saudi sickle cell disease (SCD) patients (38 males and 49 females) and 105 healthy controls (65 males and 40 females). The prevalences of factor V Leiden (P = 0.174) and PRT G20210A (P = 0.397) were not different between patients and controls, thereby giving no support to an association of either single-point mutation with SCD. However, an increased prevalence of the MTHFR 677 T/T genotype was seen among patients (8/87) compared to controls (4/105), but this was not statistically significant (P = 0.217; OR = 2.56). This suggested a low impact of inherited hypercoagulability risk factors in the pathogenesis of SCD and/or its complications.

Soluble ICAM-1 in patients with chronic hepatitis C infection: a prognostic marker of disease activity.

Soluble intercellular adhesion molecule-I (sICAM-1) is an important early marker of response to inflammatory mediators and immune activation released from a variety of cells including hepatocytes. At present, the most reliable determination of severity and prognosis in chronic viral hepatitis is the histological staging of the disease which is an invasive procedure and is often not well accepted by patients. The search for alternative non-invasive methods is mandatory especially in follow ups after initial assessment by biopsy. Serum sICAM-1 level was measured in 19 patients with chronic HCV, 19 patients with non-B, non-C chronic liver diseases (NBNC-CLD) and in 19 healthy control subjects using ELISA. Serum sICAM-1 levels were significantly higher in patients with chronic HCV and in NBNC-CLD patients compared to normal subjects (mean +/- SD, [1003 +/- 453 vs. 232 +/- 177, p<0.001], and [881 +/- 328 vs. 232 +/- 177, p<0.001]), respectively. Furthermore, serum levels of sICAM-1 were significantly higher in HCV-RNA positive patients than in HCV-RNA negative patients (p<0.001). Positive correlations were detected between serum levels of sICAM-1 and serum alanine aminotranseferase (ALT) (p<0.001), aspartate aminotranseferase (AST) (p<0.001), prothrompin time (p<0.001), and alkaline phosphatase (p<0.001), while, a negative correlation with albumin was found (p<0.001). Also, there was a significant correlation between clinical, ultrasonic findings and the level of sICAM-1 in chronic HCV patients as regards hepatomegaly, splenomegaly and normal liver echogenecity. High knodell score was significantly associated with high sICAM-1 level (p<0.001) in both patient groups. while no association between sICAM-1 and fibrosis was found. In conclusion, the measurement of sICAM-1 serum levels in chronic hepatitis C and NBNC-CLD patients is a useful non-invasive marker for monitoring liver disease activity that could replace follow up liver biopsies that are mostly not welcomed by the patients.