Simultaneous use of multiplex ligation-dependent probe amplification assay and flow cytometric DNA ploidy analysis in patients with acute leukemia

BACKGROUND

The aim of this work was to simultaneously use multiplex ligation-dependent probe amplification (MLPA) assay and flow cytometric DNA ploidy analysis (FPA) to detect aneuploidy in patients with newly diagnosed acute leukemia.

METHODS

MLPA assay and propidium iodide FPA were used to test samples from 53 consecutive patients with newly diagnosed acute leukemia referred to our laboratory for immunophenotyping. Results were compared by nonparametric statistics.

RESULTS

The combined use of both methods significantly increased the rate of detection of aneuploidy as compared to that obtained by each method alone. The limitations of one method are somehow countervailed by the other and vice versa.

CONCLUSIONS

MPLA and FPA yield different yet complementary information concerning aneuploidy in acute leukemia. The simultaneous use of both methods might be recommended in the clinical setting. © 2017 International Clinical Cytometry Society.

[Donor cell leukemia (DCL): A prospective study of its identification and treatment]

Donor-derived malignancies after allogeneic hematopoietic stem cell transplantation and after solid organ transplantation are considered as rare diseases. We have prospectively searched for donor cell leukemia in a 12-year period, in a single institution, in a group of 106 consecutive patients allografted because of leukemia. We have identified seven cases of donor cell leukemia; six were allografted because of relapsed acute lymphoblastic leukemia and one because of paroxysmal nocturnal hemoglobinuria/aplastic anemia. These figures suggest that the real incidence of donor cell leukemia has been underestimated. The six patients with lymphoblastic donor cell leukemia were treated prospectively with a pediatric-inspired combined chemotherapy schedule designed for de novo acute leukemia. A complete response was obtained in three out of six patients with lymphoblastic donor cell leukemia. It is possible to obtain favorable responses in donor cell leukemia patients employing combined chemotherapy. The long-term donor cell leukemia survivors remain as full chimeras and have not needed a second transplant.

The mutation profile of JAK2, MPL and CALR in Mexican patients with Philadelphia chromosome-negative myeloproliferative neoplasms

CONTEXT AND OBJECTIVE

By using molecular markers, it is possible to gain information on both the classification and etiopathogenesis of chronic myeloproliferative neoplasias (MPN).

METHODS

In a group of 27 Mexican mestizo patients with MPNs, we studied seven molecular markers: the BCR/ABL1 fusion gene, the JAK2 V617F mutation, the JAK2 exon 12 mutations, the MPL W515L mutation, the MPL W515K mutation, and the calreticulin (CALR) exon 9 deletion or insertion. Patients with the BCR/ABL1 fusion gene were excluded. We studied 14 patients with essential thrombocythemia (ET), eight with polycythemia vera (PV), four with primary myelofibrosis (MF), and one with undifferentiated MPN.

RESULTS

We found twelve individuals with the JAK2 V617F mutation; five of them had been clinically classified as PV, five as ET, and one as MF. One patient with the MPL W515L was identified with a clinical picture of ET. Five patients with the CALR mutation were identified, four ET and one MF. No individuals with either the MPL W515K mutation or the JAK2 exon 12 mutations were identified. The most consistent relationship was that between PV and the JAK2 V617F mutation (p=.01).

CONCLUSIONS

Despite its small size, the study shows much less prevalence of JAK2 mutation in PV, ET and MF, which does not match international data.

Pharmacogenetic selection of volunteers increases stringency of bioequivalence studies; the case of clopidogrel

Clinical response to clopidogrel varies widely due to under-dosing, drug interactions and intrinsic interindividual differences resulting from genetic polymorphisms. Cytochrome P450-2C19 is the principal enzyme involved in the activation of the prodrug and loss-of-function alleles have been described. Upon expiration of the pharmaceutical patent of clopidogrel, generic manufacturers have started to subject interchangeable formulations to bioequivalence studies. The purpose of the current investigation was to study the effect of selection of volunteers homozygous for the CYP2C19*1 haplotype on the bioavailability of clopidogrel. A regular 2×2 bioequivalence study between two formulations of clopidogrel was performed in volunteers selected and unselected for relevant CYP2C19 haplotypes for the Mexican population. It was found that selection of volunteers homozygous for the CYP2C19*1 haplotype, increased the stringency of bioequivalence statistics and resulted in bioinequivalence of a generic clopidogrel compound that otherwise proved equivalent when tested in an open unselected population. Augmentation of bioequivalence strictness is expected to result from pharmacogenetic selection of volunteers.

Treatment of vitiligo with a chimeric monoclonal antibody to CD20: a pilot study

Five patients with active disseminated vitiligo were given 1g of a chimeric (murine/human) monoclonal antibody to CD20 in a single intravenous infusion and followed-up for 6 months. Three of the patients showed an overt clinical and histological improvement of the disease, one presented slight improvement and the remaining patient showed no changes. Improvement was neither associated with changes in laboratory parameters nor to a specific human leucocyte antigen D-related (HLA-DR) phenotype. We believe that these preliminary results are encouraging, and further clinical trials should be undertaken. An important aim should be the finding of a marker with a good response to this therapeutic approach.

Molecular biology strategies to detect residual disease

The prognostic significance of minimal residual disease (MRD) has been demonstrated for a variety of hematologic malignancies. PCR based assays are among the most important methods for identifying MRD. They are aimed at detecting genetic abnormalities of residual leukemic cells with high specificity and sensitivity and represent an important diagnostic tool to assess the quality of therapeutic response, for clinical risk assessment, and for clinical management. In the present review technical aspects of different MRD detection methods are discussed which depend on the available targets regularly present in the respective leukemia type and subtype. As such fusion transcripts, gene mutations, and clonal rearrangements of antigen-receptor genes may be available for detection. Emphasis is given on discussing benefits and limitations of MRD detection and quantification in CML, AML and ALL.

Primary thrombophilia in Mexico IX

Introduction:

The sticky platelet syndrome (SPS) seems to be a common cause of thrombosis, although no molecular substrate to explain platelet hyperaggregability has been found.

Objective:

To analyze an association between the SPS phenotype and the platelet glycoprotein (GP) IIIa PLA1/A2 (human platelet antigen [HPA]-1a/b) gene polymorphism.

Methods:

Along an 18-month period, Mexican mestizo thrombophilic patients were prospectively accrued. The SPS phenotype was assessed by aggregometry, whereas a tetra-primer amplification refractory mutation system (ARMS) polymerase chain reaction analysis was used to detect the PLA1 and PLA2 alleles.

Results:

A total of 95 individuals with SPS and 127 healthy donors were studied; in 11 of the donors and 16 of the patients with SPS the A2 allele of the GP IIb/IIIA was found, yielding a weak and nonsignificant association (odds ratio 2.14, 95% CI 0.94-4.85).

Conclusion:

In Mexican mestizo patients, the platelet GP IIIa PLA1/A2 gene polymorphism does not lead to the SPS phenotype.

The impact of medical education and networking on the outcome of leukemia treatment in developing countries. The experience of International Consortium on Acute Promyelocytic Leukemia (IC-APL)

OBJECTIVES

Several clinical trials conducted in Europe and US reported favorable outcomes of patients with APL treated with the combination of all trans retinoic acid (ATRA) and anthracyclines. Nevertheless, the results observed in developing countries with the same regimen was poorer, mainly due to high early mortality mainly due bleeding. The International Consortium on Acute Promyelocytic Leukemia (IC-APL) is an initiative of the International Members Committee of the ASH and the project aims to reduce this gap through the establishment of international network, which was launched in Brazil, Mexico and Uruguay.

METHODS

The IC-APL treatment protocol is similar to the PETHEMA 2005, but changing idarubicin to daunorubicin. All patients with a suspected diagnosis of APL were immediately started on ATRA, while bone marrow samples were shipped to a national central lab where genetic verification of the diagnosis was performed. The immunofluorescence using an anti-PML antibody allowed a rapid confirmation of the diagnosis and, the importance of supportive measures was reinforced.

RESULTS

The interim analysis of 97 patients enrolled in the IC-APL protocol showed that complete remission (CR) rate was 83% and the 2-year overall survival and disease-free survival were 80% and 90%, respectively. Of note, the early mortality rate was reduced to 7.5%.

DISCUSSION

The results of IC-APL demonstrate the impact of educational programs and networking on the improvement of the leukemia treatment outcome in developing countries.

Core binding factor acute myeloid leukemia (CBF-AML) in México: a single institution experience

Twenty one patients with CBF-AML presented prospectively in the Centro de Hematología y Medicina Interna de Puebla (Puebla, México) between February 1995 and March 2010, 14 with the t(8;21)(q22;q22) and 7 with the inv(16)(p13;q22)/t(16;16)(p13;q22); they represent 13% of all cases of AML. The median age of the patients was 24 years (range 1 to 61). Seven of 14 patients with t(8;21)(q22;q22) had an M2 morphology whereas 3/7 with the inv(16) had an M4 morphology; in addition to the myeloid markers identified by flow-cytometry (surface CD13, surface CD33, and cytoplasmic myeloperoxidase) lymphoid markers were identified in the blast cells of 8/14 cases of the t(8;21) patients, but in no patient with the inv(16). Nineteen patients were treated with combined chemotherapy and 16 (84%) achieved a complete molecular remission. Seven patients were auto or allografted. Relapses presented in 10/16 patients. The median probability of overall survival (OS) has not been reached being above 165 months, whereas the 165-month probability of OS and leukemia-free survival was 52%; despite a tendency for a better outcome of patients with the t(8;21), there were no significant differences in survival of patients with either the t(8;21) or the inv(16). In this single institution experience in México, we found that the CBF variants of AML have a similar prevalence as compared with Caucasian populations, that the co-expression of lymphoid markers in the blast cells was frequent in the t(8;21) and that these two AML subtypes were associated with a relatively good long-term prognosis. Further studies are needed to describe with more detail the precise biological features of these molecular subtypes of acute leukemia.

Methotrexate-induced mucositis in acute leukemia patients is not associated with the MTHFR 677T allele in Mexico

Methylenetetrahydrofolate reductase (MTHFR) has two common variants with reduced activity due to polymorphisms at nucleotides 677 and 1298. Both affect folate metabolism and thus remethylation of homocysteine, but are also thought to affect nucleotide synthesis and DNA methylation. Methotrexate (MTX), which interrupts folate metabolism, is used in the treatment of a variety of diseases including acute lymphoblastic leukemia (ALL), but exerts in some patients toxic effects on fast dividing tissues such as mucosal epithelia. The enhanced toxicity may be due to cooperative effects between MTX and MTHFR variants. Accordingly, it has been reported that carrying the 677T allele of the MTHFR is a risk factor for MTX-associated mucositis. As in the Mexican population, which is characterized by a high prevalence of the 677T MTHFR variant, several of its commonly associated defects have not been observed, we investigated the relationship between MTX toxicity and the 677T allele. Out of 28 patients with ALL (CC: 2, CT: 10, TT: 16), 16 had episodes of MTX-associated mucositis (CC: 0, CT: 6, TT: 10). Neither at the gene level nor at the genotype level was a significant association with mucositis found. It may be postulated that the risk of higher MTX toxicity in patients with decreased MTHFR activity could be neutralized by the normally folate rich diet in Mexico.

Clearance of the Janus kinase 2 (JAK2) V617F mutation after allogeneic stem cell transplantation in a patient with myelofibrosis with myeloid metaplasia

A patient with myelofibrosis with myeloid metaplasia displaying the V617F mutation of the JAK2 gene was given an allogeneic stem cell transplantation using a reduced-intensity conditioning regimen. The patient engrafted, and as he became a chimera, the expression of the V617F mutation of the JAK2 gene decreased progressively until its disappearance. Accordingly, the concept of "molecular remission" of the myelofibrosis with myeloid metaplasia could be entertained and added to the categories of response to treatment which have been recently described.

Donor cell leukemia: a critical review

Approximately 40 cases of DCL have been reported in the literature; cases have been reported after allografts from bone marrow, peripheral blood and cord blood. The study of these cases may provide new insights into the mechanisms of leukemogenesis. Some data suggest that the prevalence of this complication has been under-estimated. Most cases of DCL have occurred following transplantation for leukemia, but there have also been cases reported after transplantation for non-malignant conditions. Various mechanisms have been proposed to explain how DCL arise and are briefly discussed. Additional studies are needed to define with more detail both the true prevalence of this complication and its precise pathogenetic mechanism.

The Janus Kinase 2 (JAK2) V617F mutation in hematological malignancies in México

A new mutation (V617F) affecting the JAK2 gene has been recently described as acquired in patients with myeloproliferative disorders and other myeloid malignancies. Using an amplification refractory mutation system, we investigated this mutation in 70 Mexican mestizo patients with hematological malignancies: 28 cases of acute lymphoblastic leukemia, 17 cases of Ph1-positive chronic myelogenous leukemia, 8 patients with acute myelogenous leukemia, 6 patients with chronic lymphocytic leukemia, 6 patients with polycythemia vera (PV), two patients with essential thrombocythemia (ET), one patient with hypereosinophilic syndrome one patient with primary myelofibrosis (MF) and one patient with chronic myelomonocytic leukemia. The mutation was identified in 4 of 6 patients with PV, in one of 2 patients with ET and in the patient with MF. Our data add to the observation that the JAK2 V617F mutation seems to be rather uncommon in myeloid malignancies other than the classic BCR/ABL negative MPD.

Molecular characterization of alpha-thalassemia in the Mexican population

BACKGROUND

alpha-Thalassemia (alpha-Thal) has been poorly characterized at the molecular level in Mexico.

METHODS

106 consecutive individuals identified in Laboratorios Clínicos de Puebla, with either hypochromia (MCH < 24 pg) and/or microcytosis (MCV < 75 fl in women or < 80 fl in man), without iron deficiency, with or without anemia were investigated in this study, along a 16 month-period. alpha and beta-Thal were looked for, the former were characterized at the molecular level.

RESULTS

Out of the 106 consecutive cases with hypochromia and/or microcytosis and normal levels of protoporphyrin zinc complex, 48 cases (45.3%) had thalassemia (37 cases of betaThal and 11 cases of alphaThal), whereas in 58 cases (54.7%) a definite diagnosis could not be established. Of the alpha-Thal cases, 8 were heterozygous and two were homozygous for the -alpha3.7 deletion, whereas one case was heterozygous for the alpha2Hph allele.

CONCLUSIONS

Only few of the alpha-Thal alleles tested were found, thus the alpha-thalassemic mutations, present in the studied population, seem to be rather heterogeneous.

HFE-Codon 63/282 (H63D/C282Y) Gene Variants in Mexican Mestizos Are Not Risk Factors for Leukemia

BACKGROUND

In some Caucasian populations it has been found that the C282Y hemochromatosis (HFE) gene mutation is a risk factor for the development of leukemia and other malignancies.

METHODS

In a group of 50 Mexican mestizo patients and 153 normal controls, the HFE gene mutations H63D and C282Y were studied by means of ARMS-PCR.

RESULTS

In the group of patients with leukemia we found a heterozygote for the C282Y mutation, seven heterozygotes for the H63D mutation, a double heterozygote for the H63D / C282Y mutation and 41 normal homozygotes. These data are not different from those observed in normal controls, where the allele frequencies were 0.062 and 0.013 for the H63D and C282Y HFE gene mutations, respectively.

CONCLUSIONS

These HFE gene mutations are not risk factors for the development of leukemia in Mexican mestizos.

Primary thrombophilia in Mexico. V. A comprehensive prospective study indicates that most cases are multifactorial

Over a 36-month period, 46 consecutive Mexican mestizos with a clinical marker associated with a primary hypercoagulable state were prospectively assessed by searching for the sticky platelet syndrome (SPS), the activated protein C resistance (aPCR) phenotype, coagulation protein C activity and antigen, coagulation protein S, antithrombin III, plasminogen, tissue-type plasminogen activator activity, plasminogen activator inhibitor activity, plasminogen activator inhibitor type 1, IgG and IgM isotypes of antiphospholipid antibodies, homocysteine levels, the factor V gene Leiden, Cambridge, Hong Kong, and Liverpool mutations, the 677 C-->T mutation in the 5,10-methylenetetrahydrofolatereductase (MTHFR), and the G20210A polymorphism in the 3'-untranslated region of the prothrombin gene. Of the 46 consecutive patients prospectively accrued in the study, only 12 (26%) were males, the median age being 38 years (range 10-63 years). In only four individuals (8%) could we not record any abnormality. In 5/42 patients with abnormal results (12%), a single abnormality was recorded, whereas in the remaining 37, two to five co-existing abnormalities were identified. We found 22 (48%) patients with the SPS, 11 (24%) with the aPCR phenotype, 5 (11%) with the factor V Leiden mutation, 7 (15%) with the prothrombin gene mutation, 29 (63%) with the MTHFR gene mutation, 11 (24%) with the factor V HR2 haplotype, 11 (24%) with antiphospholipid antibodies, 4 (9%) with PS deficiency, 6 (13%) with PC deficiency, one with the FV Hong Kong mutation, and one with AT-III deficiency. The results are consonant with the idea that most cases of thrombophilia in Mexico are multifactorial.

More on geographic hematology: the breakpoint cluster regions of the PML/RARalpha fusion gene in Mexican Mestizo patients with promyelocytic leukemia are different from those in Caucasians

Acute promyelocytic leukemia is characterized the PML/RARalpha chimeric fusion gene, transcript and protein; the breakpoint cluster regions (bcr) in the PML gene may occur in 3 different sites: Intron 6 (bcr1), exon 6 (bcr2) or intron 3 (bcr3). In a 10-year period in a single institution, we studied prospectively the breakpoint cluster regions of the PML/RARalpha fusion gene in 43 Mexican Mestizo patients with APL, and found that the bcr1 represented 62.7%, the bcr2 9.3% whereas the bcr3 27.9%. The prevalence of the bcr1 subtype is significantly higher than that informed in Caucasians and similar to that in Asians; these data are consonant with those described in other Latin-American patients with APL. Since other Asian genetic markers have been found in the Indian component of the Mexican mestizos, it is possible that the Asian immigration into the Americas through the strait of Behring 12,000 years ago may account for a possible genetic susceptibility to suffer certain forms of APL.

Frequencies of the breakpoint cluster region types of the BCR/ABL fusion gene in Mexican Mestizo patients with chronic myelogenous leukemia

There is little information about the breakpoint cluster regions of the BCR/ABL fusion gene in Mexican Mestizos with Philadelphia chromosome positive chronic myelogenous leukemia; in a small study a different distribution of these as compared with Caucasians was recently described. We have now prospectively analyzed the breakpoint cluster regions of the BCR/ABL fusion gene in a group of 238 Mexican Mestizos patients with Philadelphia chromosome positive chronic myelogenous leukemia and found a prevalence of 54.2% for the b3/a2 subtype, 43.2% for the b2a2 and 2.5% for the b3a2/b2a2. These data are not different from those previously described in other populations and are consonant with the prevalence of chronic myelogenous leukemia in Mexico, which is not different from that described in other populations.

Primary thrombophilia in Mexico IV: frequency of the Leiden, Cambridge, Hong Kong, Liverpool and HR2 haplotype polymorphisms in the factor V gene of a group of thrombophilic Mexican Mestizo patients

The activated protein C resistance (APCr) phenotype is found in around 40% of thrombophilic Mexican Mestizo individuals; since only very few display the factor V gene Leiden (Arg506Gln) mutation, it was considered of interest looking for other factor V gene mutations associated to thrombophilia: The HR2 haplotype, the factor V Cambridge (Arg306Thr), the factor V Hong Kong (Arg306Gly) and the FV Liverpool (Ile359Thr). In 39 individuals, the FV Leiden was found in 10%, the HR2 haplotype in 28%, the FV Hong Kong in 2%, whereas the FV Cambridge and FV Liverpool gene mutations were not found in any individual. In the subset of 10 patients with the APCr phenotype, the FV Leiden mutation was found only in 4 (40%) whereas the HR2 haplotype in 3 (30%); all the patients with the factor V Leiden mutation and 27% of those with the HR2 phenotype displayed the APCr phenotype. It is concluded that these polymorphisms of the factor V gene are not major contributors to the thrombophilia observed in Mexican Mestizos and that additional mutations in the FV gene should be looked for in those who display the APCr phenotype.

The Mexican schedule to conduct allogeneic stem cell transplantation is related to a low risk of cytomegalovirus reactivation and disease

The prevalence of cytomegalovirus (CMV) reactivation and disease after non-myeloablative stem cell transplantation is largely unknown. Using fludarabine combined with alemtuzumab or antithymocyte globulin in the conditioning regimen, some authors have found increased prevalences of CMV disease, whereas other authors using different schedules have observed decreased prevalences. In a group of 17 individuals allografted using the Mexican conditioning regimen, which employs fludarabine, cyclophosphamide, and busulfan, we assessed CMV reactivation, morbidity, and mortality. Before transplant, IgG anti-CMV antibodies were found in 11 patients and in 10 donors; in 8 cases, both donor and patient had IgG anti-CMV antibodies. In only one case (6%) was CMV mRNA identified 30 days after the allograft during grade IV acute graft-versus-host disease. CMV reactivation, disease, and mortality were very low using our non-myeloablative stem cell transplantation schedule, which has been shown to be useful for allografting with minimal toxicity and reduced costs.

Follow up of hemopoietic chimerism in individuals given allogeneic hemopoietic stem cell allografts using an immunosuppressive, non-myeloablative conditioning regimen: a prospective study in a single institution

Thirty consecutive patients were given non-myeloablative stem cell transplants (NST) and posttransplant chimerism was studied by several methods. In 16 individuals definitive proofs of chimerism have been shown: In 10 cases sex chimerism, in 7 cases chimerism shown by means of microsatellites, in 4 cases ABO chimerism, in two cases Rh chimerism and in one HLA-DR chimerism. In addition, in 9 individuals the disappearance of the molecular marker of the leukemia is an indirect evidence of the chimerism, as well as the presence of graft versus host disease (GVHD) in 17 allografted patients. Only in 6 patients no evidence of chimerism could be shown; all of them died as a result of either persistent or relapsing malignancy. Since the early patterns of chimerism may be predictive of either GVHD or graft loss in NST and, since therapeutic intervention (such as donor lymphocytes infusions) is based in the patterns of chimerism, it is possible that chimerism studies in these types of allografts should be ideally done more frequently than in conventional allotransplants.

Molecular monitoring of the treatment of patients with BCR/ABL (+) chronic myelogenous leukemia

BACKGROUND

The molecular follow-up of patients with chronic myelogenous leukemia (CML) has been described as useful in other countries, but there are not data reported in Mexico.

METHODS

All patients studied at Laboratories Clínicos de Puebla/Centro de Hematología y Medicina Interna de Puebla in which the BCR-ABL hybrid gene was identified by means of polymerase chain reaction were analyzed. In 22 individuals the molecular marker of the disease was studied at diagnosis and in different instances afterwards; these patients were treated with chemotherapy, interferon, autologous or allogeneic bone marrow transplantation.

RESULTS

Only the six patients that were allografted from HLA-identical siblings cleared the molecular marker of the disease; the rest of them did not achieve molecular remissions. The median survival (SV) of the whole group has not been reached, whereas the 53-month SV is 68%. One of the allografted patients died as a result of complications of graft versus-host disease.

CONCLUSIONS

We have found useful the molecular monitoring of the treatment of patients with CML. Using this approach, we found that molecular remissions can be accomplished only with allografting; however, other therapeutic approaches may also result in long-lasting hematologic remissions.

Heterozygosity for the H63D mutation in the hereditary hemochromatosis (HFE) gene may lead into severe iron overload in beta-thalassemia minor: observations in a thalassemic kindred

Heterozygosity for beta-thalassemia (minor) by itself does not lead into iron overload; however, when it is inherited together with a homozygous state for either the H63D or the C282Y mutations of the hereditary hemochromatosis gene (HFE gene), iron overload may ensue. We describe here a kindred in which the propositus, being heterozygote for beta-thalassemia and the H63D mutation of the HFE gene, developed severe iron overload and in turn, chronic liver failure with portal hypertension. Other members of the family with either beta-thalassemia or heterozygous for the H63D gene mutation did not develop iron overload. The interaction between beta-thalassemia and hereditary hemochromatosis is briefly discussed and speculations about other possible genetic mutations leading into familial iron loading are done.

Primary thrombophilia in Mexico. II. Factor V G1691A (Leiden), prothrombin G20210A, and methylenetetrahydrofolate reductase C677T polymorphism in thrombophilic Mexican mestizos

We have shown that in Mexican mestizo patients with clinical features of primary thrombophilia, 39% have activated protein C resistance phenotype, 5% protein C deficiency, and 2% protein S deficiency. In the present study, in a group of 37 thrombophilic Mexicans and 50 normal controls, we assessed the factor V G1691A (Leiden), the prothrombin G20210A, and the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphisms. Four patients were found to be heterozygous for factor V Leiden, 5 heterozygous for the prothrombin 20210, 16 heterozygous, and 6 homozygous for the MTHFR 677. There were four individuals with co-segregation of alleles: two heterozygotes for the factor V Leiden/prothrombin 20210, one heterozygote for prothrombin 20210/MTHFR 677, and one heterozygote for prothrombin 20210/homozygote for MTHFR 677. For factor V Leiden, prothrombin 20210, and MTHFR 677 mutations, the allele frequencies were respectively 1% (+/-0.2%, alpha = 0.05), <1% and 51% (+/-5%, alpha = 0.05), with calculated relative risks for thrombosis of 5.94 (P = 0.08), >7.66 (P < 0.05), and 0.44 (P NS), respectively. In Mexican mestizo thrombophilic patients, the low prevalence of the factor V Leiden mutation (10.8%) and the high prevalence of the prothrombin 20210 mutation (13.5%) contrast with those identified in Caucasian thrombophilic patients (21% and 6%, respectively; P < 0.01). On the other hand, the high prevalence of the MTHFR 677 mutation gene both in normal controls (78%) and thrombophilic patients (61%) does not support a role of this mutation in the thrombogenesis of Mexican mestizo patients.

Analysis of HFE-codon 63/282 (H63D/C282Y) gene variants in mexican mestizos. Blood donors and patients with hereditary hemochromatosis

BACKGROUND

The prevalence of hereditary hemochromatosis (HH) (H63D/C282Y) gene variants in Mexico is unknown.

METHODS

Using amplification refractory mutation system polymerase chain reaction, an analysis of HFE-codon 63/282 (H63D/C282Y) gene variants was performed in a group of 153 Mexican mestizo blood donors and six individuals with familial iron overload.

RESULTS

In normal blood donors, three heterozygotes for the C282Y mutation (2.0%) were found, whereas 18 heterozygotes and one homozygote for the H63D mutation (11.8% and 0.6%, respectively) were identified; there was one compound heterozygote for the C282Y/H63D mutation. These data resulted in allele frequencies of 0.013 (+/-0. 2%, alpha = 0.05) and 0.062 (+/-0.9%, alpha = 0.05), respectively, for these two mutations, results similar to those found in whites. In the six patients with the HH phenotype, two were found to be heterozygous for C282Y and one heterozygous for H63D; three individuals with HH had no gene mutations. Two heterozygous HH individuals were found to have iron overload associated with other conditions: one heterozygous for C282Y infected with HIV, and another heterozygous for H63D with heterozygous beta-thalassemia.

CONCLUSIONS

The prevalence of C282Y and H63D HFE gene mutations in Mexican mestizos is similar to that found in other populations. In addition, other gene mutations responsible for HH in the Mexican mestizo population should be investigated, because, in three of six individuals with the HH phenotype, neither of the two mutations was recorded.

Assessment of residual disease in acute leukemia by means of polymerase chain reaction

Along a 5-year period in a single institution, specific molecular markers were prospectively looked for in consecutive patients with acute leukemia, by means of polymerase chain reaction (PCR): In patients with acute lymphoblastic leukemia (ALL), the BCR/ABL and TEL-AML1 fusion transcripts as well as clonotypic immunoglobulin gene rearrangements were investigated, whereas in patients with acute myelogenous leukemia (AML) the PML-RAR alpha, AML1-ETO and CBF beta-MYH11 fusion proteins were assessed. Specific molecular markers were identified in 15/75 patients: Four with ALL (three with clonotypic IgG rearrangements and one with BCR/ABL) and 11 with AML (nine with the PML/RAR alpha fusion protein--M3 AML-, and two with the AML1/ETO fusion protein--M2 AML-). During follow-up periods ranging from 1 to 60 months, seven patients cleared the residual disease assessed by PCR (RD-PCR), whereas eight patients had either persistence of RD-PCR or a molecular relapse. For patients without or with RD-PCR, the 30-month survival (SV) was 86% and 14%, respectively, whereas median SV was > 60 and two months, also respectively (p < 0.01). Six of eight patients with detectable RD-PCR died, all of them within three months after the detection of the RD-PCR, whereas two of the patients that relapsed were rescued with treatment and entered a second molecular remission. Two of the three molecular relapses were detected without an overt morphological relapse. It is concluded that PCR is a valuable method for assessing residual disease and that early diagnosis of relapses may lead into effective salvage treatment in some instances.

The G20210A polymorphism in the 3'-untranslated region of the prothrombin gene in Mexican mestizo patients with primary antiphospholipid syndrome

In an effort to identify alleles associated with an increased risk of venous thrombosis in patients with primary antiphospholipid syndrome, we studied the G20210A polymorphism (the G-->A mutation at nucleotide position 20210) in the 3'-untranslated region of the prothrombin gene in a group of 14 patients with primary antiphospholipid syndrome. We did not find any patient with the mutated gene. Since the prothrombin mutation is more prevalent in white populations, this finding may be related with the genetic composition of the Mexican mestizos, in whom the white component is low. The polymorphism of the prothrombin gene in Mexican mestizo patients with antiphospholipid syndrome does not seem to be related to the thrombophilia observed in these patients.

Primary thrombophilia in Mexico: a prospective study

A group of 102 Mexican Mestizo patients with appropriate clinical features suggestive of primary thrombophilia was prospectively studied. Thirty-nine percent of them had activated protein C resistance, but only four patients displayed the factor V Leiden mutation. Five percent of the individuals were found to be protein C deficient, whereas 2% had protein S deficiency. No cases of abnormalities in antithrombin III, plasminogen, tissue-type plasminogen activator or plasminogen activator inhibitor were found. The low prevalence of the activated protein C resistance genotype, probably stemming from the genetic admixture of the Mexican Mestizo group is noteworthy.

Molecular follow-up of patients with promyelocytic leukaemia treated with all-trans retinoic acid

Six consecutive patients with promyelocytic leukaemia displaying the PML/RAR-alpha fusion messenger ribonucleic acid (mRNA)--the molecular marker of the disease--were prospectively treated with all-trans retinoic acid: Haematological complete remission was achieved in all of them. However, in three of them the PML/RAR-alpha mRNA persisted. Subsequent treatment with ablative chemotherapy rendered the molecular remission in all cases. Two of the patients that did not achieve the molecular remission with ATRA were autografted with peripheral blood stem cells after clearing the PML/RAR-alpha fusion mRNA. One patient with tretinoin-induced molecular remission relapsed two years after diagnosis and died; the remaining five survive in complete haematological and molecular remission for periods ranging from 405 to 1695 days. Additional studies are needed to clarify the significance of the molecular follow-up of patients with PML.

Tuberculosis-associated fatal hemophagocytic syndrome in a patient with lymphoma treated with fludarabine

A patient with a stage IV high-grade non-Hodgkin's lymphoma who developed a fatal hemophagocytic syndrome is presented: When the patient had achieved complete remission and receiving fludarabine and chlorambucil/prednisone, she developed miliary tuberculosis, the CD4+ T-cell count then being 50/microL; the hemophagocytic syndrome ensuing at this point was fatal. Speculations about the predisposing factors that could have led to this complication are discussed focusing on the severe cellular immunosuppression which developed probably related to the use of fludafabine: it could be useful in the future to use anti-tuberculous prophylaxis in selected patients treated with this purine nucleoside analog.

Inherited activated protein C resistance in a patient with familial primary antiphospholipid syndrome

The mechanism of thrombophilia in patients with antiphospholipid antibodies (aPL) is not clearly understood. A number of contributing factors have been described, but more than one may be operative. It was recently found that aPL may cause the acquired activated protein C resistance phenotype, whereas in familial thrombophilia, activated protein C resistance frequently results from a point mutation in the factor V gene (replacing arginine 506 with a glutamine) that leads into the (R-506-Q), the so-called Leiden mutation, that produces a mutated factor V, resistant to the catalytic action of activated protein C, otherwise normal in its procoagulant properties. We describe one patient heterozygous for the activated protein C resistance genotype with a familial form of primary antiphospholipid syndrome, who had a nephew who died with this disease. In individuals who are heterozygous for the factor V Leiden mutation, the presence of aPL may cause further activated protein C resistance, resulting in increased thrombophilia.

Activated protein C resistance phenotype and genotype in patients with primary antiphospholipid syndrome

We studied both inherited and acquired activated protein C (APC) resistance in a group of 22 patients with primary antiphospholipid syndrome (APS). The APC resistance genotype was assessed using a PCR-based analysis for the factor V R506Q (Leiden) mutation. One patient with primary APS was found to be heterozygous for the factor V Leiden mutation. He and other family members were affected by severe thrombophilia and had a familial form of primary APS. The APC resistance phenotype was assessed by measuring the prolongation of the activated partial thromboplastin clotting time in response to APC. It was found in five out of six patients with APS, in one of them transiently. We have found that the APC resistance phenotype is more frequent than the genotype in primary APS. It would seem that patients with thrombophilia should be investigated for APC resistance even if found to have antiphospholipid antibodies and/or lupus anticoagulants.