Role of glutathione S-transferase P1 polymorphism in early transplant complications in patients undergoing allogeneic stem cell transplantation.

INTRODUCTION: Complications in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) cause serious morbidity and mortality. Predicting patients at risk in advance and changing the symptomatic care and/or preparation regimen according to this risk assessment have been emphasized recently. Several single-nucleotide polymorphisms have been studied, and some were found to be responsible for early complications. Glutathione S-transferase P1 (GSTP1) is an enzyme involved in the detoxification process that reduces oxidative stress by reducing the number of free oxygen radicals. AIM: This study aimed to investigate the relationship between GSTP1 polymorphism and early complications of allo-HSCT, iron parameters, overall survival (OS), and transplantation-related mortality (TRM). MATERIALS AND METHODS: A total of 50 patients diagnosed with acute myeloid leukemia (n = 23) or acute lymphoblastic leukemia (n = 27) who underwent allo-HSCT between May 2008 and February 2011 at Gazi University Faculty of Medicine, Stem Cell Transplantation Unit, were included. RESULTS: Of the 50 patients, 24 (48%) were women and 26 (52%) were men. The median age of the patients was 26 (16-74) years. GSTP1 polymorphism was detected in 23 (46%) patients, and 27 (54%) had no polymorphism (wild type). The two groups were compared in terms of early toxicity after transplantation, according to the preparation regimen. The group with GSTP1 polymorphism was found to have a high transferrin saturation index (P < 0.05). Patients with no GSTP1 polymorphism showed a high grade III-IV anemia ratio (P < 0.05). The presence of sinusoidal obstruction syndrome and graft-versus-host disease was similar in both groups (P > 0.05). OS and TRM were higher in the GSTP1 polymorphism group, but no statistical difference was found between the two groups (P > 0.05). CONCLUSIONS: TSI was higher in the GSTP1 polymorphism group. GSTP1 polymorphism had no effect on early transplantation complications. Although the OS and TRM ratios were higher in the GSTP1 polymorphism group, no statistically significant difference was found between the groups. Further studies with larger sample size are needed.

The prognostic role of hemochromatosis H63D allele in allogeneic hematopoietic stem cell transplantation.

Iron overload is considered as a significant cause of morbidity and mortality in hematopoietic stem cell transplant (HSCT) recipients. The presence of hemochromatosis gene (HFE) mutations might exacerbate iron toxicity in the post-transplant setting. This prospective study was planned to evaluate the genetic spectrum of HFE mutations in Turkish patients undergoing HSCT and the impact of HFE genotype on transplant morbidity and mortality. HFE genotypes of 102 patients [median age, 27.5 years (16-64 years); male/female, 73:29], who underwent allogeneic HSCT, were analyzed. Twenty-two patients were heterozygous and 1 patient was homozygous for the H63D mutation, while the C282Y mutation was observed in none of our patients. The frequency of invasive fungal infections (IFI) was significantly higher in H63D-mutated patients (p=0.004). H63D mutation was identified as an independent risk factor for the development of IFI (p=0.006, OR=0.554, SE=0.208), without an impact on overall survival and transplant-related mortality. The multifactorial iron-overloaded state in HSCT recipients might affect the phenotypic expression of HFE mutations and alter the severity of clinical presentation. The impact of HFE genotype on iron parameters and transplant-related morbidity and mortality should be validated with further studies.

Thiopurine methyltransferase polymorphisms and mercaptopurine tolerance in Turkish children with acute lymphoblastic leukemia.

PURPOSE: Thiopurine methyltransferase (TPMT) enzyme is involved in the metabolism of 6-mercaptopurine (6-MP), a key component of acute lymphoblastic leukemia (ALL) treatment protocols in children. The aims of this study were to investigate the frequency of common genetic polymorphisms associated with low TPMT activity and correlations of polymorphic variants with 6-MP tolerance in a group of Turkish children with ALL. METHODS: Genotyping for G238C, A719G, and G460A mutations were performed by using NanoChip Technology. Adverse reactions during the first 6 months of maintenance therapy with oral 6-MP and methotrexate were retrospectively analyzed from patient's files. RESULTS: Five (8.6%) of 58 children with ALL had a polymorphic TPMT allele: 4 (3.4%) were heterozygous for TPMT*3A (G460A and A719G), and one (0.9%) was heterozygous for TPMT*3C (A719G). No cases with TPMT*3B (G460A) or TPMT*2 (G238C) variants were identified. Children with TPMT*3A and *3C had significantly lower leukocyte and neutrophil counts and percentage of target 6-MP dosage, and longer periods with ≥grade 2 infections, ≥grade 2 liver toxicity, and chemotherapy interruptions than the children with wild-type TPMT during the first 24 weeks of maintenance therapy. CONCLUSIONS: The frequency and distribution of common TPMT polymorphisms in Turkish children with ALL is similar to other Caucasian populations. Polymorphic variants were associated with excessive 6-MP toxicity supporting the suggestion that TPMT genotyping should be performed before institution of 6-MP therapy.