Risks of red blood cell alloimmunization in transfusion-dependent ß-thalassemia in Oman: a 25-year experience of a university tertiary care reference center and a literature review.

BACKGROUND: ß-Thalassemia is a common hemoglobinopathy in the Arabian Peninsula. Red blood cell (RBC) transfusion is a cornerstone for its management, but can create significant challenges including RBC alloimmunization. Herein, we examine alloimmunization risk factors in Omani patients with transfusion-dependent ß-thalassemia. Existing literature is summarized. STUDY DESIGN AND METHODS: A retrospective review of all patients attending our center over 25 years was performed. Clinical and transfusion records were examined. Chi-square test was used to assess the association between the categorical variables. Nonparametric Mann-Whitney test was used to assess the association between transfusion and risk of alloimmunization. RESULTS: A total of 268 patients were identified (168 adults and 100 pediatrics), of whom 226 are alive (84.3%). Males accounted for 53.4%. The cohort had a median age of 22 years (range, 2-43 years). The most common blood group was O+ (39%). The prevalence of alloimmunization was 9.3% with anti-E (24%) and anti-K (24%) being the commonest antibodies identified. There was a significant association between age and alloimmunization, with 68% of alloimmunized patients in the age group of 19 to 30 years (p < 0.01). Among adults, there was a significant association between alloimmunization and number of units transfused (p = 0.001). There was no association between alloimmunization and sex or history of splenectomy. CONCLUSION: Our study shows an association between alloimmunization and the age of the patients and number of units transfused. Transfusion support of this group of patients necessitates the availability of needed expertise and blood bank facilities.

Vincristine-induced neuropathy in pediatric patients with acute lymphoblastic leukemia in Oman: Frequent autonomic and more severe cranial nerve involvement.

BACKGROUND: Vincristine (VCR) induced peripheral neuropathy is a common complication in children with acute lymphoblastic leukemia (ALL). PROCEDURES: A retrospective data analysis over an interval of 10 years (2006-2016) of all children with ALL seen at Sultan Qaboos University Hospital was carried out. Electronic medical records of eligible patients were reviewed. Patients with clinical evidence of neuropathy and abnormal nerve conduction studies (NCSs) were included in the study. RESULTS: Nineteen (nine females and 10 males) out of 103 pediatric patients developed VCR-related neuropathy, and their age ranged between 2.5 and 14 years. Symptoms started after 2-11 doses of VCR. All 19 patients had documented peripheral neuropathy on NCSs. The autonomic nervous system and cranial nerves affection was relatively common in our patients; two presented with bradycardia, two patients with unexplained tachycardia, and five had abdominal pain and constipation, complicated by typhlitis in two patients. One patient developed unilateral hearing loss. Two patients developed severe life-threatening cranial nerve involvement with bilateral ptosis and recurrent laryngeal nerve involvement presented as vocal cord paralysis, hoarseness of voice, frequent chocking, and aspiration episodes. CONCLUSIONS: Peripheral neuropathy was the commonest form of VCR-related neuropathy. Autonomic neuropathy was relatively common in our patients. Cranial neuropathy is a serious side effect of VCR that can be severe, involving multiple cranial nerves and needs prompt recognition and management. Concomitant administration of pyridoxine and pyridostigmine does not seem to protect against further neurological damage in some patients.

Transcranial Doppler ultrasonography in sickle cell disease: a study in Omani patients.

Changes on Transcranial Doppler (TCD) ultrasonography have been proposed as significant predictors of cerebrovascular complications in sickle cell disease (SCD). However, consensus with regards to the TCD criteria to recognize abnormalities in cerebral vasculature is lacking. We studied the TCD characteristics of cerebral arteries among Omani patients with SCD and correlated them with cerebrovascular events. TCD was performed through the temporal and suboccipital windows using a 2 MHz probe (DWL). Thirty-three of 59 patients (56%) with SCD had neurological symptoms including stroke--12 (20%) and epilepsy--7. Fifteen patients (25%) had significant TCD abnormalities including: markedly increased velocities--11 (3 with stroke); turbulent flow--2; and reversal of flow--2. No patient had a time averaged maximum mean velocity of >200 cm/s in anterior circulation. On applying a modified definition of "abnormal TCD" to anterior and posterior circulation studies, increased TCD velocities in posterior circulation correlated with history of stroke (P < 0.05). TCD velocities in the 18 adult patients ( older than 15 y) were significantly lower than in children. Logistic regression analysis revealed abnormal TCD in the left posterior cerebral artery to be an independent predictor of stroke in this cohort (P = 0.035).

Cytogenetic profile of childhood acute lymphoblastic leukemia in Oman.

BACKGROUND: Chromosomal abnormalities have important diagnostic and prognostic significance in acute lymphoblastic leukemia (ALL). The purpose of this study was to define and classify the frequency and type of chromosomal abnormalities among newly diagnosed children with ALL and compare the results with those reported from other geographical regions of the world. METHODS: Bone marrow chromosomal studies with GTG banding were performed in untreated ALL pediatric patients aged from 7 days to 14 years. RESULTS: Among Omani children examined with ALL, 47 (81%) patients yielded results, with 26 (55.3%) showing an abnormal karyotype [10 (21.3%) pseudodiploid, 2 (4.3%) hypodiploid and 14 (29.7%) hyperdiploidy] and 21 (44.6%) had normal diploidy. Structural abnormalities were observed in 16 (34%), of which 11 (23.4%) cases were translocations, the most frequent being t(9;22) observed in three (6.4%) of our patients. Uncommon translocations such as t(9;15)(p11;q10), t(3;6)(p12;q11), t(1;6)(?31;?q23), t(1;19)(q12;q12), der(18)t(12;18)(q11;p11), and other structural aberrations add(2)(q22), add(6)(q16), add(18)(q22), add(14)(q32) along with deletions del(10)(q22), del(12)(p11), del(12)(p12), del(18)(q11) were also observed. CONCLUSIONS: The study showed a good correlation and concordance between the ploidy distribution by cytogenetics and flow cytometry. The patterns of chromosomal anomalies in our patients showed some variations in the frequency of aberrations reported. It is therefore necessary that newer techniques like fluorescence in situ hybridization (FISH) along with reverse transcriptase polymerase chain reaction (RT-PCR) and spectral karyotyping will help us identify chromosomal aberrations not detected by conventional cytogenetic methods in the near future. To our knowledge, this is the first report from the Middle East of a cytogenetic study on childhood ALL.

Pulsed high-dose dexamethasone therapy in children with chronic idiopathic thrombocytopenic purpura.

The effectiveness of pulsed high-dose oral dexamethasone therapy in children with refractory chronic idiopathic thrombocytopenic purpura (ITP) is evaluated. Thirteen children with severe chronic ITP were enrolled in the study from an outpatient pediatric hematology clinic (ages 2-14 years), 5 boys and 7 girls. They did not maintain a response to other forms of therapy (IVIg, Anti-D, conventional steroids, danazol) and one girl relapsed after splenectomy. Dexamethasone was administered orally at a dosage of 40 mg/M2/day (maximum 40 mg/day) for 4 consecutive days. The cycle was repeated once a month for 6 months. The immediate response to therapy was excellent as the mean platelet count at day 1 was 15 x 10(9)/L, while mean platelet count at day 4 was 158 x 10(9)/L. At the end of 6 cycles 3 patients maintained a platelet count of >150 x 10(9)/L and 4 patients showed partial response. At the end of the first year and second year (12 and 24 months after onset of treatment) 3 patients still had complete response, 3 patients had partial response, and 7 patients were failures. Six of the failures underwent splenectomy and one was shifted to dapsone, had no response, and refused splenectomy. Side effects were tolerable. They included bloating, nausea, vomiting, insomnia, anxiety, and depression, and transient glucosuria; however, they were not severe enough to discontinue the cycles. Mean duration of illness prior to start of dexamethasone was not significantly different in between responders and nonresponders. Dexamethasone given orally in high doses is an effective drug in achieving short-term platelet responses. Long-term remission is obtained in nearly half the patients with well-established chronic ITP. Its effectiveness in almost half the patients, minimal side effects, and low cost indicate that this treatment should be considered in patients with chronic ITP who do not tolerate the disease well before considering splenectomy.