Seven novel mutations in the factor XIII A-subunit gene causing hereditary factor XIII deficiency in 10 unrelated families.

BACKGROUND: Hereditary factor (F)XIII deficiency is a rare bleeding disorder mostly due to mutations in FXIII A subunit. OBJECTIVES: We studied the molecular basis of FXIII deficiency in patients from 10 unrelated families originating from Israel, India and Tunisia. METHODS: Exons 2-15 of genomic DNA consisting of coding regions and intron/exon boundaries were amplified and sequenced. Structural analysis of the mutations was undertaken by computer modeling. RESULTS: Seven novel mutations were identified in the FXIIIA gene. The propositus from the Ethiopian-Jewish family was found to be a compound heterozygote for two novel mutations: a 10-bp deletion in exon 12 at nucleotides 1652-1661 (followed by 22 altered amino acids and termination codon) and Ala318Val mutation. The propositus of the Tunisian family was homozygous for C insertion after nucleotide 863 within a stretch of six cytosines of exon 7. This insertion results in generation of eight altered amino acids followed by a termination codon downstream. The propositus from Indian-Jewish origin was found to be homozygous for G to T substitution at IVS 11 [+1] resulting in skipping of exons 10 and 11. In addition to the Ala318Val mutation, three of the novel mutations identified are missense mutations: Arg260Leu, Thr398Asn and Gly210Arg each occurring in a homozygous state in an Israeli-Arab and two Indian families, respectively. CONCLUSIONS: Structure-function correlation analysis by computer modeling of the new missense mutations predicted that Gly210Arg will cause protein misfolding, Ala318Val and Thr398Asn will interfere with the catalytic process or protein stability, and Arg260Leu will impair dimerization.     

Assessment of the coagulation profile in hemato-oncological patients receiving ATG-based conditioning treatment for allogeneic stem cell transplantation

Antithymocyte globulin (ATG) is increasingly used in pre-allogeneic stem cell transplantation (allo-SCT) conditioning regimens to prevent graft rejection and graft-versus-host disease. However, ATG was also found to be associated with increased incidence of thrombosis during organ transplantation. In the present study, we tested the coagulation status of 21 patients with hematologic malignancies undergoing allo-SCT who received ATG-based (11 patients) or non-ATG-based (10) conditioning treatment. We assessed several thrombophilia markers as well as circulating total and endothelial microparticles (TMP/EMP) and soluble CD40 ligand (CD40L). No significant difference in the mean values of prothrombin time, partial thromboplastin time, fibrinogen, antithrombin, protein C, protein S, thrombin-antithrombin III complex, homocysteine levels, prevalence of genetic thrombophilia markers and levels of EMP, TMP or CD40L was observed between the ATG-treated and ATG-untreated patients, as well as before and after conditioning in each group separately. Platelet counts decreased significantly in ATG-treated patients; however, this decrease was not associated with clinical or laboratory evidence of disseminated intravascular coagulation. No patient developed thromboembolic event or veno-occlusive liver disease. Our results suggest that allo-SCT is not associated with increased hypercoagulability and addition of ATG to conditioning regimen has no significant procoagulant effect.     

Lymphocyte urosynthase in non-Hodgkin's lymphoma. An indicator of disease extensiveness

The activity of lymphocyte uroporphyrinogen synthase (URO-S) was examined in 51 non-Hodgkin's lymphoma (NHL) patients at various follow-up periods. Mean +/- SD activity (pmol porphyrin/mg protein/hr) at diagnosis (n = 24), on relapse (n = 14) and during active disease (n = 14) were 31.7 +/- 19.8, 31.7 +/- 27.2 and 29.4 +/- 18.5, respectively. These values were significantly higher than the enzyme activity during remission (14.1 +/- 4.0), which was in the normal range (14.5 +/- 3.8). Abnormally high activity was found in 65.4% of determinations at diagnosis, on relapse and during active disease, compared to 5.5% during remission (P less than 0.001). Significant association of abnormal URO-S activity was found with advanced clinical stage (P less than 0.01), spleen enlargement (P = 0.048), involvement of bone marrow (P = 0.02), as well as lymphoma cell spread to peripheral blood (P = 0.03). Highly significant correlation (r = 0.65, P less than 0.001) was found between URO-S activity and serum lactic dehydrogenase (LDH) levels. Excessively high levels of URO-S activity were found only in patients with lymphoma cells in peripheral blood. No association was found with histopathologic classification and liver size. The authors conclude that URO-S activity is a biochemical indicator for patients in all stages of NHL and seems to be a specific marker for the extensiveness of the disease.     

Evaluation of multiplex real‐time PCR for identifying dermatophytes in clinical samples—A multicentre study

The gold‐standard method for dermatophyte identification involves direct microscopy and culture, which have inherent shortcomings. Only few molecular methods have been standardised for routine clinical work. This study aimed to develop and test a platform for identifying the most common dermatophytes in Israel using multiplex real‐time polymerase chain reaction (RT‐PCR). Specific primers were designed for the multiplex system (LightCycler 480) according to known cultures and validated by reference isolates. The dermatophyte detection rate was compared to smear and culture in 223 clinical samples obtained from a tertiary medical centre. Inconsistencies between methods were evaluated by sequencing. The RT‐PCR was further evaluated in 200 community‐based samples obtained from a health maintenance organisation and 103 military‐personnel‐based samples analysed at a central laboratory. In hospital‐based clinical samples, complete concordance between methods was observed in 190 samples (85%; Kappa = 0.69). In most cases of non‐concordance, sequencing was consistent with RT‐PCR results. RT‐PCR correctly identified all smear‐ and culture‐positive cases in community and military‐personnel samples. The results were available within 4 hours. The multiplex RT‐PCR platform is a rapid and efficient method for identifying dermatophyte species in clinical samples and may serve as a first step in the diagnostic algorithm of superficial fungal infections.     

Diagnosis of thrombotic thrombocytopenic purpura based on modulation by patient plasma of normal platelet adhesion under flow condition

We have designed a simple test for the early diagnosis and treatment monitoring of thrombotic thrombocytopenic purpura (TTP). We examined plasma from 24 TTP patients and normal plasma using a cone and plate(let) analyser (CPA). Test plasma was mixed with citrated normal whole blood (group O) and subjected to flow at a shear rate of 1800/s. Mixing normal plasma (12.5, 25, 50 or 75 microl) with heterologous normal whole blood (final volume of 200 microl) resulted in a decrease of surface coverage (SC, maximally by 63%) and, to a lesser extent, of average size (AS, maximally by 37%) due to dilution of the blood sample. In contrast, mixing the same quantities of acute TTP plasma with normal blood yielded an increase in both SC (up to 125%) and AS (up to 130%). Increased SC and/or AS were detected in all 15 patients in acute phase and in three out of 14 patients in remission. Following repeated plasmapheresis, the enhanced platelet deposition in five patients with acute TTP returned to almost normal patterns. Mixing plasma from patients with other thrombocytopenic conditions in this way resulted in a decrease in both SC and AS, and did not differ from control subjects. In conclusion, the CPA is a simple and specific laboratory test that can be used for the diagnosis and monitoring of plasma exchange therapy in TTP.