Transcobalamin deficiency - a rare genetic defect in transportation of cobalamin; case report.

BACKGROUND: Vitamin B12 is primarily transported from plasma to cells by Transcobalamin. Deficiency of Transcobalamin is a rare autosomal recessive disorder that results in unavailability of cobalamin in cells and accumulation of homocysteine and methylmalonic acid. CASE REPORT: We report a case of a 2-year-old male child with persistent pancytopenia, recurrent infections, and megaloblastic anemia. Next-generation sequencing identified a novel variant in exon 8 of TCN2 gene. Substantial improvement has been observed following administration of high doses of parenteral methylcobalamin. CONCLUSION: In patients with unresolved pancytopenia and megaloblastic anemia, Transcobalamin deficiency should be investigated and treated promptly to prevent any irreversible and harmful outcome.

Antibiotic Stewardship: A Handshaking Strategy Among Physicians and Pharmacists to Improve therapeutic Outcomes in Hematology-Oncology.

Background: Infections are highly susceptible in patients with hematological malignancies due to immune suppression, immunosuppressive therapies and disease progression. Rational use of antibiotics following Antimicrobial Stewardship (AMS) guidelines in early detection and response to infection is significant to improve patient care. Objectives: The present study was conducted to determine the impact of clinical pharmacists' interventions (PIs) on antibiotics usage in hematology-oncology set up in Karachi, Pakistan. Methodology: An observational prospective study was conducted for a period of 4 months in a well-known 75-bed teaching hospital, specializing in bone marrow transplantation in Karachi, Pakistan without a structured Antimicrobial stewardship programs (ASPs). The information was gathered from patient medical histories, laboratory, and microbiological records. Results: A total of 876 PIs (1 to 5 per patient) were implemented. Dose modifications or interval changes accounted for the major interventions (n = 190, 21.6%). The majority of all recommendations were related to antipseudomonal ß-lactams, aminoglycosides, sulfamethoxazole-trimethoprim and vancomycin. Overall, 94.3% (n = 876) of the 928 PIs were accepted. Conclusion: The PIs and the high physician acceptance rate may be useful for improving the safe use of antibiotics, lowering their toxicity, lowering the need for special-vigilance medications and potentially improving patient care.

Haematopoietic Stem Cell Transplant Trends in Pakistan: Activity Survey from Pakistan Bone Marrow Transplant Group.

Pakistan is the fifth most populous country with a population of 225 million and has health expenditure accounting for only 2.8 percent of gross domestic product (GDP). Accordingly, there are a limited number of haematology-oncology and transplant centers in the country. The Pakistan Blood and Marrow Transplant (PBMT) group was established in 2020, and this report is the first activity survey from January 2021 to December 2022 focusing on the trends of matched-related donor, haploidentical, and autologous transplants in a developing country. A total of 12 transplant centers contributed data on the modified PBMT survey form retrospectively and 806 haematopoietic stem cell transplants (HSCTs) were carried out during the study duration. Allogeneic HSCT constituted 595 (73.8%) of all the transplants; this is in stark contrast to Western data, where autologous HSCT accounts for the majority of transplants. ß-thalassemia major and aplastic anemia were the commonest indications for allogeneic HSCT, in contrast to Western data, where acute leukemia is the leading transplant indication. Autologous transplants were more frequently performed for Hodgkin's lymphoma as compared to non-Hodgkin's lymphoma and multiple myeloma. The use of peripheral and bone marrow stem cells was comparable. A myeloablative conditioning regimen was routinely used in patients with acute leukemia. This report provides an insight of HSCT trends in Pakistan which are different from those of Western centers contributing to transplant data from South Asia.

Development of a Thalassemia International Prognostic Scoring System (TIPSS).

A prognostic scoring system that can differentiate ß-thalassemia patients based on mortality risk is lacking. We analysed data from 3145 ß-thalassemia patients followed through a retrospective cohort design for the outcome of death. An a priori list of prognostic variables was collected. ß Coefficients from a multivariate cox regression model were used from a development dataset (n = 2516) to construct a formula for a Thalassemia International Prognostic Scoring System (TIPSS) which was subsequently applied to a validation dataset (n = 629). The median duration of observation was 10.0 years. The TIPSS score formula was constructed as exp (1.4 × heart disease + 0.9 × liver disease + 0.9 × diabetes + 0.9 × sepsis + 0.6 × alanine aminotransferase ≥42 IU/L + 0.6 × hemoglobin ≤9 g/dL + 0.4 × serum ferritin ≥1850 ng/mL). TIPSS score thresholds of greatest differentiation were assigned as <2.0 (low-risk), 2.0 to <5.0 (intermediate-risk), and ≥5.0 (high-risk). The TIPSS score was a good predictor for the outcome of death in the validation dataset (AUC: 0.722, 95%CI: 0.641-0.804) and survival was significantly different between patients in the three risk categories (P < 0.001). Compared to low-risk patients, the hazard ratio for death was 2.778 (95%CI: 1.335-5.780) in patients with intermediate-risk and 6.431 (95%CI: 3.151-13.128) in patients with high-risk. This study provides a novel tool to support mortality risk categorization for patients with ß-thalassemia that could help management and research decisions.

Incorporating a clinical oncology pharmacist into an ambulatory care pharmacy in pediatric hematology-oncology and transplant clinic: Assessment and significance.

BACKGROUND: Beta thalassemia patients, post-bone marrow transplant, and leukemia patients require long term therapy with an intense care follow-up especially for pediatric hematology-oncology origin. Emergence of side effects and noncompliance to therapy lead to reduced efficacy of medicines resulting in relapse of diseases. There is an increasing fact to support the incorporation of a pharmacist into clinical team due to their distinctive skills. Clinical oncology pharmacist with experience and specialized training in hematological cancers and bone marrow transplantation (BMT) patient care has in-depth knowledge and skills of chemotherapy regimens including drug information, monitoring parameters of cancer treatment, dose adjustment, drug-drug interactions, adverse effects, and patient counseling skills. AIM AND OBJECTIVES: The main objective of our study was to assess the significance of incorporation of clinical oncology pharmacist in ambulatory care in pediatric hematology-oncology and transplant clinic. MATERIAL AND METHOD: This study was conducted at National Institute of Blood Diseases and Bone Marrow Transplantation hospital with duration of five months from 17 March 2019 to 16 July 2019. In this study the clinical oncology pharmacist was made available at ambulatory clinic of hematology-oncology and transplantation. The activities performed by a clinical oncology pharmacist were observed by resident BMT clinical pharmacist during the visits of patients and their families in a clinic. The BMT pharmacist is a clinical oncology pharmacist with experience and specialized training in hematological cancers and BMT patient care. Only pediatrics patients with beta thalassemia major and those who were on chemotherapy treatment and post-transplant patient were included in this study. RESULTS: During the five months' tenure, there were 1820 pediatric patients' visits in total. The clinical oncology pharmacist performed 980 direct patient interviews and documented 1665 pharmacist interventions. The majority of the documented clinical oncology pharmacist interventions were review of medication histories (n: 404, 24%) and "deferiprone" dose adjustments (n:400, 24%). Genomic profiling interventions were also among the commonly reported activities by the clinical oncology pharmacist. For beta thalassemia patients undergoing hydroxyurea therapy, the genomic profiling was performed to assess whether the hydroxyurea treatment is clinically effective or not (n:396, 23%). CONCLUSION: The involvement of clinical oncology pharmacist into a specialized outpatient clinic of hematology-oncology and transplant clinic plays an integral role in minimizing the adverse effect and reduction in readmission into the hospital. This is new expansion of pharmacist's role especially in underdeveloped country, considering the relevant clinical participation of clinical oncology pharmacist into specialized clinic revealing through optimized therapy and future prospect of clinical oncology pharmacist in pediatric hematology.

Seasonal variations in hematological disorders: A 10-year single-center experience.

AIMS: To assess the seasonal variations in hematological disorders among patients diagnosed on the basis of bone marrow biopsy, who attended National Institute of Blood Diseases (NIBD) clinics during 2006 to 2015. METHODS: We retrospectively reviewed the 10-year records of hematological disorders among patients' NIBD clinics from year 2006 to 2015. All cases of aplastic anemia (AA), acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), immune thrombocytopenic purpura (ITP), and acute promyelocytic leukemia (APML) were categorized on the basis of the seasons in which they were diagnosed such as winter (December-February), spring (March-May), southwest monsoon periods (June-September), and retreating monsoon period (October and November). Statistical analysis was performed by using SPSS and STATA. Inferential statistics were explored using the chi-square test for heterogeneity to evaluate seasonal variations. P-value <0.05 was taken as significant. RESULTS: A total of 1982 cases were reviewed. Men were predominantly higher (n = 1190, 60%) as compared to women (n = 792, 40%). Frequency of ALL was found to be higher (513, 25.9%), followed by ITP (504, 25.4%), AML (490, 24.7%), AA (396, 20%), while APML was observed in only 79 (4%) patients. Seasonal variations in the diagnosis of hematological disorders were observed (P-value < .001), except in APML diagnosis (P-value = .445). Significant seasonal variations were also detected in both genders in stratified analysis. CONCLUSION: The finding of this study has reported an increase in the hematological disorder during 2006 to 2015. Particularly, majority of the cases were reported in southwest monsoon period, whereas least cases were reported in retreating period. Significant seasonal and yearly variations were detected in all diagnosis except the APML.

Peripheral Blood Stem Cell Harvest HPC Count Is an Effective Surrogate Marker for CD34+ Cell Count in Allogeneic Stem Cell Transplant Setting.

OBJECTIVE: We assessed the predictive potential of XN-HPC for CD34+ cell count as obtained through Sysmex automated hematology analyzers (XN-1000). METHODS: This study was conducted at the National Institute of Blood Diseases and Bone Marrow Transplantation in 84 donors between December 2012 and December 2017 in the first phase and later validated in 112 donors between December 2017 and December 2018. Sysmex XN-1000 and BD FACS Calibur estimated XN-HPC and CD34+ cells of peripheral blood apheresis product, respectively. Spearman's correlation was assessed between XN-HPC and CD34+ cell count followed by receiver operating characteristic curve calculation to determine the XN-HPC cutoff for a CD34+ count of ≥2 million cells/kg of recipient's body weight RESULTS: There is a moderately positive correlation (P value = .003) between XN-HPC and CD34+ count. Receiver operating characteristic curve analyses demonstrated that a cutoff value for XN-HPC of ≥1·845×106cells/kg of recipient's body weight has a specificity and sensitivity of 100% and 78·2%, respectively, for predicting the CD34+ count of ≥2 million cells/kg of recipient's body weight. This cutoff value of XN-HPC was prospectively validated in 112 donors. The positive predictive value was found to be 100%, while negative predictive value was 17%. CONCLUSION: XN-HPC has a highly promising potential to serve as a cost-effective and time-saving surrogate for CD34+ cell count.

Frequency of Alpha Thalassaemia in homozygous Beta Thalassaemia paediatric patients and its clinical impact at a blood disease centre in Karachi, Pakistan.

OBJECTIVE: To find frequency ofalpha Thalsaemia nhomozygous beta Thalsaemia patients, and to se any difernce infrequency and age ofirst ransfusion and mean haemoglobin concentration. METHODS: The single-centred, escriptive cros-sectional study was conducted athe National Instiute of Blod Disease and Bone Marow Transplantaion, Karchi, from June 1,2012, to May 31, 2013. Patients of homozygous beta halsaemia, diagnosed by polymerase chain reaction, wer tested for coinheritance of alpha Thalsaemia nd foetal haemoglobin XMN1 polymorphism using polymerase chain reaction. SPS 17 was used for dat anlysi. RESULTS: Of the 286 patients, 19(41.6%) wer males, and 9(34.6%) showed coinheritance ofalpha thalsaemia. In the coinheritance group, 50(50%) and 1(1%) patients recived 1-20 and 21-40 times transfusions per year espectively, while inthe non-coinheritance group, the coresponding numbers wer 125(67%) and 27(14.%). Overal, 73(25.%) patients had nevr ben transfused, including 38(13.%) patients inthe alpha Thalsaemia group. XMN1 polymorphism was found in 86(41%) ofthe 208 patients who wer tested and anlysed on this count. CONCLUSIONS: Alpha thalsemia was presnt inmore than one-third homozygous beta halsemia patients.

Early and sustained deep molecular response achieved with nilotinib in high Sokal risk chronic myeloid leukemia patients.

BACKGROUND: Nilotinib (Tasigna®) is a second-generation tyrosine kinase inhibitor that shows faster and deeper molecular responses (MR) in comparison to Imatinib as initial therapy in chronic phase chronic myeloid leukemia (CML). Efficacy and safety data for nilotinib in the Asian population is scarce, particularly in Pakistan. We aimed to determine the MR to nilotinib and its safety profile in patients with chronic phase CML. PATIENTS AND METHODS: This observational study was conducted among 173 patients with newly diagnosed CML presenting in the chronic phase. Most patients (50.1%) had a high Sokal score at diagnosis. All patients received nilotinib 600 mg/day. The hematological and molecular responses were assessed at 3 and 6 months respectively and thereafter at 6-monthly intervals. Long-term event free survival (EFS), transformation free survival (TFS), overall survival (OS) and adverse events were observed. RESULTS: Cumulative incidence of major MR (MMR) was 86% and deep MR (DMR ie MR 4.0 and MR4.5) was 39%. Early MMR and DMR after 6 months of therapy were achieved by 74.9% and 37% of patients, respectively. Two-year EFS, TFS and OS rates for all patients were 91.9%, 92% and 92.3%, respectively. At median follow-up of 24 months, 81% and 49% of patients sustained MMR and DMR, respectively. The main adverse events were weight gain (4.6%) and abdominal pain (4%). CONCLUSION: This study showed promising results in terms of achievement of early and sustained DMR in chronic phase CML, therefore, we recommend nilotinib as frontline treatment in Pakistani population.

Reflection of treatment proficiency of hydroxyurea treated ß-thalassemia serum samples through nuclear magnetic resonance based metabonomics.

ß-Thalassemia is a widespread autosomal recessive blood disorder found in most parts of the world. Fetal hemoglobin (HbF), a form of hemoglobin is found in infants, replaced by adult hemoglobin (HbA) after birth. Hydroxyurea (HU) is one of the most effective HbF inducer used for the treatment of anemic diseases. We aimed to improve the understanding of HU therapy in ß-thalassemia by metabonomics approach using 1H NMR spectroscopy. This study includes 40 cases of ß-thalassemia before and after HU therapy along with 40 healthy as controls. Carr-Purcell-Meiboom-Gill (CPMG) sequence was used to identify forty-one putative metabolites. Generation of models like partial least square discriminant analysis (PLS-DA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) based on different metabolites including lipids, amino acids, glucose, fucose, isobutyrate, and glycerol revealed satisfactory outcomes with 85.2% and 91.1% classification rates, respectively. The concentration of these metabolites was altered in ß-thalassemia samples. However, after HU treatment metabolic profile of same patients showed closeness towards healthy. Deviant metabolic pathways counting lipoprotein changes, glycolysis, TCA cycle, fatty acid and choline metabolisms were identified as having significant differences among study groups. Findings of this study may open a better way to monitor HU treatment effectiveness in ß-thalassemia patients, as the results suggested that metabolic profile of ß-thalassemia patients shows similarity towards normal profile after this therapy.

Hydroxyurea Treated ß-Thalassemia Children Demonstrate a Shift in Metabolism Towards Healthy Pattern.

Augmentation of fetal hemoglobin (HbF) production has been an enduring therapeutic objective in ß-thalassemia patients for which hydroxyurea (HU) has largely been the drug of choice and the most cost-effective approach. A serum metabolomics study on 40 patients with ß-thalassemia prior to and after administration of HU was done along with healthy controls. Treated patients were divided further into non-responders (NR), partial (PR) and good (GR) per their response. 25 metabolites that were altered before HU therapy at p ≤ 0.05 and fold change >2.0 in ß-thalassemia patients; started reverting towards healthy group after HU treatment. A prediction model based on another set of 70 HU treated patients showed a good separation of GR from untreated ß-thalassemia patients with an overall accuracy of 76.37%. Metabolic pathway analysis revealed that various important pathways that were disturbed in ß-thalassemia were reverted after treatment with HU and among them linoleic acid pathway was most impactfully improved in HU treated patients which is a precursor of important signaling molecules. In conclusion, this study indicates that HU is a good treatment option for ß-thalassemia patients because in addition to reducing blood transfusion burden it also ameliorates disease complications by shifting body metabolism towards normal.

Detection of the Incidence of HBV, HCV Infection and Febrile Neutropenia Associated With CHOP With or Without Rituximab in Diffuse Large B-Cell Lymphoma-Treated Patients.

Background: Reactivation of hepatitis B virus (HBV) and hepatitis C virus (HCV) and febrile neutropenia (FN) are common in diffuse large B-cell lymphoma (DLBCL) patients undergoing cyclophosphamide, hydroxyrubicin, Oncovin, and prednisolone (CHOP) or cyclophosphamide, hydroxyrubicin, Oncovin, prednisolone - rituximab containing (R-CHOP) chemotherapy. This ultimately leads to delaying the therapy, increasing hospital stay, and raising the pharmacoeconomic burden on patients. Aim and Objective: The aim of this study was to determine the incidence of HBV and HCV infection and febrile neutropenia in DLBCL patients treated with R-CHOP and CHOP. Methodology: This was an institutional approved study in which patient records from a private hospital, specialized in hematology and oncology (Karachi, Pakistan), were reviewed retrospectively from 2014 to 2016. Patients aged above 18 years with known diagnosis of DLBCL who underwent CHOP-21 or R-CHOP-21 chemotherapy regimen were included. Baseline blood chemistry and liver function tests along with the data regarding HBV (hepatitis B surface antigen [HBsAg], hepatitis B surface antibody [anti-HBs]), HCV (antibody anti-HCV), and febrile neutropenia were collected from patient records. Results: In total, 35 cases of DLBCL were treated during a 3-year period (ie, from 2014 to 2016), of which 16 were on CHOP-21 regimen whereas 19 were treated with R-CHOP-21. Of the 19 patients who underwent R-CHOP chemotherapy, only 2 (10%) patients were HBsAg reactive. Before commencing the second cycle, 2 (10%) patients reported to hospital with fever and had hematological (low neutrophil count) and microbiological (Escherichia coli) proven febrile neutropenia. The incidence of HBV infection post treatment was lower in group treated with CHOP (1 patient showed HBsAg reactivity).

Detection of the Incidence of Infections and Acute Biochemical Changes in Diffused Large B-Cell Lymphoma Patients Treated with Cyclophosphamide, Doxorubicin, Vincristine and Prednisone (CHOP) with and without Rituximab.

BACKGROUND: Acute biochemical changes, hepatotoxicity, nephrotoxicity and frequency of infections are common in diffuse large B-cell Lymphoma patients undergoing Cyclophosphamide, Doxorubicin, Oncovin (Vincristine) Prednisone (CHOP) and Rituximab plus CHOP chemo cycles. Eventually, it leads to prolonging hospital stay and suspending the next chemotherapy cycles. AIMS AND OBJECTIVES: The objectives of our study were to determine the changes in biochemical disturbances induced by CHOP or RCHOP and second objective was to compare the effect of CHOP with or without rituximab on the incidence of the infections such as (Cytomegalovirus, Herpes Simplex Virus and Varicella-Zoster virus), bacterial infections and tuberculosis. MATERIALS AND METHODS: Files were prospectively reviewed during the tenure of 2014-2016. Participants aged greater than or equal to 18 years old with a known case of DLBCL undergoing CHOP or RCHOP chemotherapy were allowed to be included in the study. Baseline and posttreatment patients profile of blood chemistry, liver functions test was collected and compared with the Common Terminology Criteria for adverse events v3.0 2009 CTCAE 2009 and the data regarding infection of Cytomegalovirus, Herpes Simplex Virus and Vericella-Zoster virus, bacterial infections and tuberculosis were drawn from the participant's profile. RESULTS: Patients treated with CHOP therapy showed a significant difference of Alkaline Phosphatase (ALP) (p-value 0.009), direct bilirubin (p-value 0.034) and serum glutamic-pyruvic transaminase (SGPT) (p-value 0.004). Bacterial Pneumonia was only 1 (5%) and 1 (5%) CMV reported positive after the R-CHOP. CONCLUSION: We propose that liver profile including (bilirubin, SGOT and SGPT) Urea, Creatinine and electrolytes should strictly be considered if found deranged before every treatment cycle and suspend chemotherapy in case of moderate or severe toxicity.

Quantitative assessment of metal dysregulation in ß-thalassemia patients in comparison with healthy controls by ICP-MS and chemometric analyses.

ß-Thalassemia is one of the most common inherited disorders and is widely distributed throughout the world. Owing to severe deficiencies in red blood cell production, blood transfusion is required to correct anemia for normal growth and development but causes additional complications owing to iron overload. The aim of this study is to quantify the biometal dysregulations in ß-thalassemia patients as compared with healthy controls. A total of 17 elements were analyzed in serum samples of ß-thalassemia patients and healthy controls using ICP-MS followed by chemometric analyses. Out of these analyzed elements, 14 showed a significant difference between healthy and disease groups at p < 0.05 and fold change >3. A PLS-DA model revealed an excellent separation with 89.8% sensitivity and 97.2% specificity and the overall accuracy of the model was 92.2%. This metallomic study revealed that there is major difference in metallomic profiling of ß-thalassemia patients specifically in Co, Mn, Ni, V and Ba, whereas the fold changes in Co, Mn, V and Ba were found to be greater than that in Fe, providing evidence that, in addition to Fe, other metals are also altered significantly and therefore chelation therapy for other metals may also needed in ß-thalassemia patients.

Impact of hydroxyurea therapy on serum fatty acids of ß-thalassemia patients.

INTRODUCTION AND OBJECTIVE: Fatty acids (FAs) influence cell and tissue metabolism, function, responsiveness to hormonal and other signals in addition to maintenance of membrane integrity of cells. ß-Thalassemia is a prevalent inherited blood disorder characterized by abnormal red cell membrane structure and function. Induction of HbF by hydroxyurea (HU) is an enduring therapeutic intervention to manage this. Therefore, in the present study we have carried out the quantification of thirteen free fatty acids to disclose the prognosis of HU in ß-thalassemia. METHODS: FAs quantification was carried out using GC-MRM-MS method in the serum of 98 cases of ß-thalassemia patients and out of which samples from 34 patients were collected before and after treatment with HU in addition to healthy controls (n = 31). RESULTS: Using the combination of random forest (RF) with GC-MRM-MS we were able to establish a classification and prediction model that can discriminate the ß-thalassemia from healthy as well as from HU treated group. Docosanoic acid (C-22:0) was most significantly altered in ß-thalassemia as compared to healthy at p-value of 8.3 × 10-09 while erucic acid (C-22:1 Δcis-13) can be used as potential marker of HU prognosis because its level became significantly dissimilar at p-value of 3.7 × 10-04 in same patients in response to HU. However, nervonic acid (C-24:1 Δcis-15) was found to be the key player in effectively separating three groups. CONCLUSION: In inference, we have noticed that HU therapy also rectifies the serum fatty acid profile in addition to its reported affect i.e. HbF induction in ß-thalassemia patients.

ß-Thalassemia Patients Revealed a Significant Change of Untargeted Metabolites in Comparison to Healthy Individuals.

ß-Thalassemia is one of the most prevalent forms of congenital blood disorders characterized by reduced hemoglobin levels with severe complications, affecting all dimensions of life. The mechanisms underlying the phenotypic heterogeneity of ß-thalassemia are still poorly understood. We aimed to work over metabolite biomarkers to improve mechanistic understanding of phenotypic heterogeneity and hence better management of disorder at different levels. Untargeted serum metabolites were analyzed after protein precipitation and SPE (solid phase extraction) from 100 ß-thalassemia patients and 61 healthy controls using GC-MS. 40 metabolites were identified having a significance difference between these two groups at probability of 0.05 and fold change >1.5. Out of these 40 metabolites, 17 were up-regulated while 23 were down-regulated. PCA and PLS-DA model was also created that revealed a fine separation with a sensitivity of 70% and specificity of 100% on external validation of samples. Metabolic pathway analysis revealed alteration in multiple pathways including glycolysis, pyruvate, propanoate, glycerophospholipid, galactose, fatty acid, starch and sucrose metabolism along with fatty acid elongation in mitochondria, glycerolipid, glyoxylate and dicarboxylate metabolism pointing towards the shift of metabolism in ß-thalassemia patients in comparison to healthy individuals.

Epidemiologic and HLA antigen profile in patients with aplastic anemia.

OBJECTIVE: To analyze patients suffering from aplastic anemia (AA, peripheral pancytopenia and hypocellular bone marrow in the absence of dysplasia, infiltration and fibrosis) for documenting patient's baseline characteristics and association with various human leucocyte antigens. STUDY DESIGN: An observational, cross-sectional study. PLACE AND DURATION OF STUDY: The National Institute of Blood Disease (NIBD), Karachi, from March 2003 to August 2008. METHODOLOGY: All consecutive patients with confirmed diagnosis of AA were evaluated. Data included the baseline characteristics, complete blood counts (CBC), bone marrow biopsy findings, severity of disease, exposure to drugs or chemicals, viral serology and their HLA expression. The data was analyzed on SPSS programme and frequencies were documented. RESULTS: Among 318 patients, there were 236 (74.21%) males and 82 (25.78%) females. Median age was 16 and 70% belonged to urban population. Drug exposure could be established in 23 (7.23%) of cases, while 4 (1.25%) were HBV surface antigen positive and 7 (2.2%) were HCV antibodies positive. In all, 73 (22.9%) had very severe AA, 195 (61.32%) had severe AA while 50 (15.7%) cases had non-severe AA. HLA B5 (52) showed high expression in 83 patients (26%) in comparison to 5.9% reported in healthy population. CONCLUSION: AA was found to affect young adult males living in urban areas. HLA B5 (52) showed higher expression in patients with aplastic anemia.