β-Thalassemia and ocular implications: a systematic review

Does thalassemia truly cause microvascular changes without us noticing? An optical coherence tomography angiography study of the children with beta-thalassemia

PURPOSE

It was aimed to evaluate the retinochoroidal microvascular alterations of pediatric beta-thalassemia patients and investigate the effect of blood transfusion on perfusion among transfusion-dependent thalassemia (TDT), by means of optical coherence tomography angiography (OCTA).

METHODS

In this multicentered, prospective, cross-sectional study, 56 TDT, 14 non-TDT (NTDT), and 63 healthy children were evaluated. The vessel density (VD) in superficial capillary plexus (SCP), deep capillary plexus, radial peripapillary capillary network, choriocapillaris, and the foveal avascular zone area (FAZ) were evaluated by OCTA. Before and after transfusion values ​​of the TDT group were compared, and correlations were made with blood values ​​and iron accumulation.

RESULTS

Foveal and parafoveal zones were significantly thinner among TDT patients, with larger FAZ area. Macula VD of SCP and ppVD was lowest in NTDT group. In the TDT group, a decrease in retinal nerve fiber thickness and ppVD values was detected ​​after transfusion. A negative significant relationship was found between both hemoglobin (Hb), hematocrit (Htc), and ppVD.

CONCLUSIONS

OCTA provides a better insight into retinal and choriocapillaris vascular impairment influenced by tissue hypoxia and oxidative stress in different clinical phenotypes of beta-thalassemia.

Investigation of the color discrimination ability using the Farnsworth-Munsell 100-hue test and structural changes by SS-OCT in patients with transfusion-dependent beta-thalassemia

AIM

This study aimed to examine the color discrimination ability of patients with transfusion-dependent beta-thalassemia (TDβ-T) in detail using the Farnsworth Munsell (FM) 100-hue test and to evaluate structural changes by swept source-optical coherence tomography (SS-OCT).

MATERIAL AND METHODS

This prospective, sectional study included 40 patients (79 eyes) with TDβ-T and 21 controls (42 eyes). The volunteers underwent a detailed ophthalmological examination and SS-OCT (DRI-OCT, Triton) imaging. Excluded were those with congenital color vision defects detected with the Ishihara pseudoisochromatic test. The patients' color vision was examined using the FM 100-hue test. The total error score (TES), the blue-yellow local error score (b-y LES), and the red-green local error score (r-g LES) were calculated. p <0.05 was considered significant.

RESULTS

The mean age was 30.34±6.94 years in the patient group and 32.26±6.43 years in the control group (p = 0.078). The patient group had a significantly lower hemoglobin level (9.25±0.87 g/dL vs. 14±1.79 g/dL, p <0.001) and a significantly higher ferritin level (2665.56±2658.05 μg/L vs. 52.87±69.59 μg/L, p<0.001) compared to the control group. The mean TES, b-y LES, and r-g LES were higher in the patients than in the controls (64.84±30.18 vs. 28.45±16.55, p<0.001, 34.21±17.54 vs. 15.67±10.07, p <0.001, and 29.32±15.72 vs. 12.12±7.94, p<0.001, respectively). The patients had a higher b-y LES than r-g LES (34.21±17.54 vs. 29.32±15.72, p = 0.015). Choroidal thickness was lower in the patients than in the controls (284.34±63.55 µm vs. 324.98±88.05 µm, p = 0.043).

CONCLUSION

We found that the color discrimination ability of the patients with TDβ-T was reduced in both the r-g and b-y color axes compared to the controls, and their color discrimination ability in the b-y color axis was more affected than in the r-g axis.

Burden of ocular abnormalities in patients with beta thalassaemia: a cross-sectional study

INTRODUCTION

In Pakistan, the reported carrier rate of thalassaemia is estimated to be 5%-8% with 5000 new patients diagnosed every year. Several known systemic complications of beta thalassaemia major have been studied, but no studies are conducted to assess ocular complications among these patients from our population.

METHODS

It was a cross-sectional study design conducted at three private and public sector centres in Pakistan. We recruited 203, 11-17 years old children with beta thalassaemia major in our study. Frequency of overall ocular complications such as retinal pigment epithelium degeneration, visual field defects, increased retinal vascular tortuosity, lenticular opacities, anterior segment abnormality, etc among beta thalassaemia patients were verified by an ophthalmologist.

RESULTS

On univariate analysis male gender (prevalence ratio (PR): 1.023 (0.903 to 1.160), OGTT levels (PR: 0.99 (0.978 to 1.003) and serum calcium levels (PR: 0.716 (0.616 to 0.936)) were significantly associated with ocular complications. However, on multivariable analysis after adjusting for covariates we observed that the prevalence of ocular complications was 88% higher in males as compared with females. Moreover, with every one unit increase in serum calcium levels the prevalence of ocular complications were decreased by 24%.

CONCLUSION

Our study results showed that the frequency of ocular complications in beta thalassaemia children was 22.7%. Male gender was a risk factor for ocular complications among children with beta thalassaemia. However, high calcium levels among these patients were found to be protective for ocular complications.

Third-Generation Sequencing as a New Comprehensive Technology for Identifying Rare α- and β-Globin Gene Variants in Thalassemia Alleles in the Chinese Population

CONTEXT.—

Identification of rare thalassemia variants requires a combination of multiple diagnostic technologies.

OBJECTIVE.—

To investigate a new approach of comprehensive analysis of thalassemia alleles based on third-generation sequencing (TGS) for identification of α- and β-globin gene variants.

DESIGN.—

Enrolled in this study were 70 suspected carriers of rare thalassemia variants. Routine gap-polymerase chain reaction and DNA sequencing were used to detect rare thalassemia variants, and TGS technology was performed to identify α- and β-globin gene variants.

RESULTS.—

Twenty-three cases that carried rare variants in α- and β-globin genes were identified by the routine detection methods. TGS technology yielded a 7.14% (5 of 70) increment of rare α- and β-globin gene variants as compared with the routine methods. Among them, the rare deletional genotype of -THAI was the most common variant. In addition, rare variants of CD15 (G>A) (HBA2:c.46G>A), CD117/118(+TCA) (HBA1:c.354_355insTCA), and β-thalassemia 3.5-kilobase gene deletion were first identified in Fujian Province, China; to the best of our knowledge, this is the second report in the Chinese population. Moreover, HBA1:c.-24C>G, IVS-II-55 (G>T) (HBA1:c.300+55G>T) and hemoglobin (Hb) Maranon (HBA2:c.94A>G) were first identified in the Chinese population. We also identified rare Hb variants of HbC, HbG-Honolulu, Hb Miyashiro, and HbG-Coushatta in this study.

CONCLUSIONS.—

TGS technology can effectively and accurately detect deletional and nondeletional thalassemia variants simultaneously in one experiment. Our study also demonstrated the application value of TGS-based comprehensive analysis of thalassemia alleles in the detection of rare thalassemia gene variants.

Optical coherence tomography angiography findings in transfusion-dependent beta-thalassemia patients with and without splenectomy

BACKGROUND

Ocular involvement is common in transfusion-dependent beta-thalassemia (TDβ-T) patients. We aimed to investigate the effect of splenectomy on optical coherence tomography angiography (OCTA) findings in TDβ-T patients.

METHODS

The study is a prospective cross-sectional study. A total of 45 eyes of 23 patients with splenectomy (34.04±8.83 years), 18 eyes of 9 patients without splenectomy (27.44±5.43 years), and 54 eyes of 27 controls (33.22±6.44 years) were included. Vessel density in superficial capillary plexus, deep capillary plexus and radial peripapillary capillary, foveal avascular zone, choriocapillaris flow area, choroidal and retinal thickness detected by OCTA were evaluated. p < 0.05 was considered significant.

RESULTS

Vessel density of superficial capillary plexus and deep capillary plexus were similar in patients with and without splenectomy, and controls. Choriocapillaris flow area was significantly decreased in patients with splenectomy than that in those without splenectomy and controls (2.02±0.12 vs. 2.17±0.1 and 2.14±0.12; p < 0.001). Choroidal thickness was significantly lower in patients without splenectomy than in patients with splenectomy and controls (260.05±61.02 vs. 305.11±42.13 and 298.89±29.14, p = 0.008). Parafoveal and perifoveal thickness of the full retina and outer retina were significantly lower in patients without splenectomy than in patients with splenectomy and controls (301.06±10.0, 279.78±10.28 vs. 311.04±14.89, 290.87±13.67 and 316.63±13.57, 289.56±9.31, p < 0.001 and p = 0.002; 174.72±7.81, 167.17±6.21 vs. 182.87±8.81, 173.60±7.09 and 185.11±9.26, 173.96±6.79, p = 0.001 and p < 0.001, respectively).

CONCLUSIONS

OCTA findings can provide information about the microvascular effects of splenectomy on the retina of patients with TDβ-T.

Evaluation of parafoveal and peripapillary vascular densities using optical coherence tomography angiography in children with thalassemia major

Background:

Thalassemia major (TM) is an inherited anaemia caused by faulty haemoglobin synthesis. Reducing serum iron levels using iron chelating agents is an important step in the treatment of TM, and the effects on the eye of both the disease and these agents can be determined by regular eye examination.

Objectives:

We evaluated macular and optic nerve vascular densities in children with TM and compared the results with healthy controls using optical coherence tomography angiography (OCTA).

Design:

This is a prospective study.

Methods:

A total of 30 children with TM and 30 healthy controls were included in the study. The area of the foveal avascular zone (FAZ) and the vascular densities (VD) of the optic nerve head (ONH), radial peripapillary capillary (RPC) and deep and superficial retinal vascular networks were measured using OCTA.

Results:

A statistically significant decrease in VD was observed in the whole image and the parafovea, superior hemi, superior and inferior parts of the superficial capillary plexus and in the whole image and the superior regions of the deep capillary plexus in the TM patient group compared with the control group ( p < 0.05). A significant decrease in VD was also observed in the whole image and the inside disc, peripapillary, nasal, inferonasal and temporal regions of the ONH and in the whole image and the inside disc, peripapillary and inferonasal regions of the RPC network in patients with TM ( p < 0.05). A significant positive correlation was observed between both serum ferritin levels and deferasirox dosage, on one hand, and both the superficial ( p = 0.023 and p = 0.002, respectively) and deep FAZs ( p = 0.015 and p = 0.045, respectively), on the other hand. A negative correlation was also found between the deferasirox dosage and the VDs of the superficial ( p = 0.010) and deep ( p = 0.001) foveal plexuses.

Conclusion:

Retinal VD and FAZ are affected in patients with TM. OCTA, which can noninvasively measure retinal VD in patients with TM, may be a useful tool for the early detection of retinal microvascular changes that may occur during the course of the disease.

Ocular biometry, anterior chamber morphometry, and their relationship with serum ferritin levels in children with beta thalassemia major

Background

Ocular biometry and anterior segment evaluations are important to determine ocular development and pathological changes, especially in thalassemia patients in Mediterranean countries such as Turkey.

Objectives

The objectives of this study were to compare ocular biometry and anterior segment parameters in children with thalassemia major and healthy controls and to examine the relationship between ferritin levels, anthropometric measurements, and ocular parameters.

Design

This is a prospective case-control study.

Methods

The height, weight, body mass index, and occipitofrontal circumference values of the participants were recorded. Anterior and vitreous chamber depth, lens thickness, axial length, central corneal thickness, anterior chamber volume, iridocorneal angle, pupil diameter, and mean keratometry were measured. Measurements were compared between patients and healthy children, and between patients with ferritin levels above and below 1000 ng/mL.

Results

This study included 40 patients and 45 controls. Height, weight, and body mass index were significantly lower while ferritin level and occipitofrontal circumference were significantly higher in patients compared with the controls (p < 0.001 for all). There were no statistically significant differences in the other ocular parameters (p > 0.05). In comparisons between patients with ferritin levels below (n = 15) and above 1000 ng/mL (n = 25), there were no significant differences in age, height, weight, body mass index, occipitofrontal circumference, or ocular parameters (p > 0.05). Occipitofrontal circumference and mean keratometry value were positively correlated in patients with ferritin levels below 1000 ng/mL (r = 0.573, p = 0.025), while body mass index was negatively correlated with pupil diameter in patients with ferritin levels above 1000 ng/mL (r = -0.469, p = 0.018).

Conclusion

Children with thalassemia showed significant growth retardation and large occipitofrontal circumference but did not differ from controls in terms of biometrics and anterior segment morphology. Our results demonstrated a positive correlation between the occipitofrontal circumference and mean keratometry value in children with ferritin levels below 1000 ng/mL and a negative correlation between body mass index and pupil diameter in children with ferritin levels above 1000 ng/mL.

PATTERN DYSTROPHY-LIKE CHANGES ASSOCIATED WITH A VERY HIGH SERUM FERRITIN LEVEL IN β-THALASSEMIA MAJOR

PURPOSE

To report a rare case of pattern dystrophy-like retinal changes in a young β-thalassemia major patient with a very high serum ferritin level.

METHODS

Observational case report of a β-thalassemia major patient with bilateral pattern dystrophy-like retinal changes.

RESULTS

An 18-year-old man experienced blurring of vision in both eyes. Patient had a very high serum ferritin level and had a history of using various iron-chelating drugs. Funduscopy revealed bilateral widespread retinal pigment epithelium changes with macular involvement, which resembled pattern dystrophy-like changes. Fundus autofluorescence imaging showed extensive area of decreased autofluorescence signal interspersed with increased autofluorescence signals, whereas optical coherence tomography demonstrated macular retinal pigment epithelium thinning and interdigitation zone disruption corresponding to retinal pigment epithelium damage and atrophy.

CONCLUSION

Pattern dystrophy-like changes should be considered as a possible manifestation of retinal changes in patients with β-thalassemia major. Iron overload, which is indicated by a very high serum ferritin level, might have a role in the formation of this rare retinal manifestation in β-thalassemia major.

Optical coherence tomography findings in patients with transfusion-dependent β-thalassemia

BACKGROUND

Structural ophthalmologic findings have been reported in patients with β-thalassemia due to chronic anemia, iron overload, and iron chelation therapy toxicity in few previous studies. We aimed to investigate structural ocular findings and their relationship with hematological parameters in patients with transfusion-dependent β-thalassemia (TDT).

METHODS

In this cross-sectional study, from January 2018 to January 2019, 39 patients with TDT over the age of 18 participated. Multicolor fundus imaging, optical coherence tomography (OCT), and blue light fundus autofluorescence imaging were performed for all patients and 27 age- and sex-matched controls.

RESULTS

The mean age of patients was 28.6 ± 6.2 years. The central macular thickness and macular thicknesses in all quadrants were significantly thinner in patients than controls (P<0.05). None of the retinal nerve fiber layer (RNFL) measurements were significantly different between TDT patients and controls. There was a significantly negative correlation between hemoglobin with central macula thickness (r=-0.439, P=0.005). All measurements of macular subfield thickness were insignificantly thinner in patients with diabetes mellitus (DM) compared to the non-DM subgroup.

CONCLUSIONS

Macular thickness was significantly thinner in central macula and entire quadrants in TDT patients compared to healthy individuals; however, all RNFL measurement thicknesses were comparable between the two groups. Close monitoring of TDT patients by periodic ophthalmologic examinations with more focus on diabetic patients, patients with severe anemia and iron overload should be warranted.

Increased Endothelial Cell Density in Childhood Patients With Thalassemia Major

PURPOSE

We aimed to compare specular microscopy, biometric, refractive, and anterior segment topographic parameters in children with thalassemia major (TM) with normal children of the same age.

MATERIAL METHOD

This cross-sectional study included 55 eyes of 55 patients with TM and 63 eyes of 63 age-sex-matched healthy children; all patients with TM were receiving treatment with blood transfusions every 3 to 4 weeks and an oral iron chelator deferasirox (DFX) (ICL670) tablet. A comprehensive ophthalmic examination was performed, including refraction (spherical equivalent), best-corrected visual acuity, slit-lamp bio microscopy, specular examination, optical biometry, intraocular pressure, anterior segment topography, and fundus examination.

RESULTS

Endothelial cell density (ECD) was 3,138 in the TM group and 2,996 in the control group (P=0.003). The mean central corneal thickness was significantly thinner in the TM group (P=0.010). Flat keratometry (K1) was 43.5 D in the study group and 42.9 D in the control group (P=0.039). The mean anterior chamber depth (ACD) was shallower in the TM group (P=0.004); axial length (AL) was significantly shorter in the TM group (P=0.002).

CONCLUSION

This study shows that there are differences in ECD, AL, keratometry values, ACD, and anterior segment parameters of pediatric patients with TM compared with healthy controls.

Molecular Characterization Analysis of Thalassemia and Hemoglobinopathy in Quanzhou, Southeast China: A Large-Scale Retrospective Study

Background: There are limited reports available on investigations into the molecular spectrum of thalassemia and hemoglobinopathy in Fujian province, Southeast China. Here, we aim to reveal the spectrum of the thalassemia mutation and hemoglobinopathy in Quanzhou prefecture, Fujian province.

Methods: We collected data from a total of 17,407 subjects with the thalassemia trait in Quanzhou prefecture. Gap-PCR, DNA reverse dot blot hybridization, and DNA sequencing were utilized for common and rare thalassemia gene testing.

Results: In our study, we identified 7,085 subjects who were carrying thalassemia mutations, representing a detection rate of 40.70% (7,085/17,407). Among them, 13 different α-thalassemia gene mutations were detected, with the most common mutation being –^SEA (69.01%), followed by –α^3.7 (21.34%) and –α^4.2 (3.96%). We also discovered 26 β-thalassemia gene mutations, with the mutations of IVS-II-654 (C > T) (36.28%) and CD41/42(–TCTT) (29.16%) being the most prevalent. Besides, a variety of rare thalassemia variants were identified. Among them, the –^FIL, β^Malay, β^{IVS–I–130}, and β^{IVS–II–672} mutations were identified in Fujian province for the first time. Additionally, we detected 78 cases of hemoglobinopathies, of which Hb Owari was the first reported case in Fujian province and Hb Miyashiro was the first case identified in the Chinese population.

Conclusion: Our study indicates that there is a diverse range of thalassemia mutations, and it also reveals the mutation spectrum of rare thalassemia and hemoglobinopathies in Quanzhou, Fujian province. It provides valuable data for the prevention and control of thalassemia in Southeast China.

Do We Store Packed Red Blood Cells under "Quasi-Diabetic" Conditions?

Red blood cell (RBC) transfusion is one of the most common therapeutic procedures in modern medicine. Although frequently lifesaving, it often has deleterious side effects. RBC quality is one of the critical factors for transfusion efficacy and safety. The role of various factors in the cells’ ability to maintain their functionality during storage is widely discussed in professional literature. Thus, the extra- and intracellular factors inducing an accelerated RBC aging need to be identified and therapeutically modified. Despite the extensively studied in vivo effect of chronic hyperglycemia on RBC hemodynamic and metabolic properties, as well as on their lifespan, only limited attention has been directed at the high sugar concentration in RBCs storage media, a possible cause of damage to red blood cells. This mini-review aims to compare the biophysical and biochemical changes observed in the red blood cells during cold storage and in patients with non-insulin-dependent diabetes mellitus (NIDDM). Given the well-described corresponding RBC alterations in NIDDM and during cold storage, we may regard the stored (especially long-stored) RBCs as “quasi-diabetic”. Keeping in mind that these RBC modifications may be crucial for the initial steps of microvascular pathogenesis, suitable preventive care for the transfused patients should be considered. We hope that our hypothesis will stimulate targeted experimental research to establish a relationship between a high sugar concentration in a storage medium and a deterioration in cells’ functional properties during storage.

Ocular manifestations in patients with transfusion-dependent β-thalassemia

BACKGROUND

Ocular involvement in patients with transfusion-dependent β-thalassemia is quite common, and its frequency differs among studies. This case series aimed to describe the ocular abnormalities occurring in β-thalassemia patients who need regular blood transfusions and receive iron chelation therapy.

CASE SERIES

This is a case series prospectively studied 32 β-thalassemia patients from Northern Greece receiving regular blood transfusions and iron-chelating therapy. Patients' average age was 35.5 years. Eighteen patients with major phenotypes and fourteen patients with intermedia type underwent comprehensive ophthalmic examination at the time of enrolment, including visual acuity evaluation, refraction and color vision tests, Amsler grid test, slit-lamp, and dilated-pupil fundus examination. Additionally, we performed visual field testing and optical coherence tomography in all patients and fluorescein angiography only in selected cases. After six months, patients' complete ophthalmic examination was repeated for any new ocular findings due to the disease process and iron chelation therapy. Ocular involvement was detected in 46.87 % of the patients. Lesions were most frequently seen in elderly patients with thalassemia major. Lens opacities were present in 21.8 %, and degeneration of the retinal pigment epithelium was described in 15.6 % of the patients, representing the commonest fundus alteration observed, followed by fundus atrophy. The most severe and vision-threatening condition described in this study was the presence of angioid streaks with choroidal neovascularisation. Six months follow-up of patients did not reveal any new ocular findings.

CONCLUSION

Early detection of severe ocular abnormalities is important in patients with thalassemia; thus, an ophthalmologic examination should be included at regular check-ups. An annual examination is currently indicated for asymptomatic patients, while in symptomatic and complicated cases, patients should be closely followed-up. HIPPOKRATIA 2021, 25 (2):79-82.

Retinal and Choriocapillaris Vascular Changes in Patients Affected by Different Clinical Phenotypes of β-Thalassemia: An Optical Coherence Tomography Angiography Study

Simple Summary

β-thalassemia represents a hematological disorder that determines anomalous hemolysis and ineffective erythropoiesis. The patients, undergoing regular lifelong blood transfusion, show an iron overload in the tissues that requires an iron chelation therapy. Both iron accumulation and iron-chelating agents cause ocular manifestations, such as retinal pigment epithelial (RPE) degeneration, RPE mottling, cataract, optic neuropathy and retinal venous tortuosity. In this cross-sectional study, we described the retinal and choriocapillaris microvascular changes in different clinical phenotypes of β-thalassemia that may reflect a tissue hypoxia status and oxidative damages.

Abstract

In this cross-sectional study we assessed the vascular alterations in retinal and choriocapillaris perfusion in patients affected by β-thalassemia, by means of optical coherence tomography angiography (OCTA). A total of 124 eyes of 62 patients (mean age 44.74 ± 5.79 years old) affected by β-thalassemia (transfusion dependent thalassemia (TDT), non-transfusion dependent thalassemia (NTDT) and minor) were compared to 40 eyes of twenty healthy subjects. We evaluated the vessel density (VD) in superficial capillary plexus, deep capillary plexus, radial peripapillary capillary, choriocapillaris and the foveal avascular zone area. The TDT group showed a statistically significant reduction in retinal and choriocapillaris VD respect to controls and the other groups (p < 0.05). No statistically significant difference was found in OCTA parameters between β-thalassemia minor and controls. The NTDT group showed a significant reduction in VD in deep capillary plexus respect to controls and β-thalassemia minor. Significant negative correlations were shown in TDT group between foveal avascular zone and hemoglobin (r = −0.437, p = 0.044) and between ferritin levels and VD of choriocapillaris (r = −0.431, p = 0.038). The OCTA parameters provided a deeper understanding on retinal and choriocapillaris vascular impairment affected by tissue hypoxia levels and the oxidative stress in different clinical phenotypes of the β-thalassemia.

Novel retinal findings in β-thalassemia major: older age and higher ferritin level as the risk factors

PURPOSE

To investigate retinal changes in β-thalassemia major patients and identify their association with systemic risk factors.

METHODS

In this prospective study, 120 β-thalassemia major patients received complete ophthalmic examinations (best-corrected visual acuity, contrast sensitivity, color vision, and indirect ophthalmoscopy) and retinal imaging using color fundus photography and fundus autofluorescence imaging. Patients were grouped according to the presence of thalassemia-related retinal changes. The association between systemic risk factors (age, type and duration of iron chelator use, history of splenectomy, hemoglobin level, and ferritin level) and thalassemia-related retinal changes was investigated using logistic regression analysis.

RESULTS

Thalassemia-related retinal changes were identified in 36.7% of patients. Several distinct retinal changes were observed, including retinal refractile bodies in 10% of patients and retinal hemorrhage in 5.8% of patients. Fundus autofluorescence imaging showed abnormal patterns in 36.3% of patients with thalassemia-related retinal changes and 18.4% of patients without thalassemia-related retinal changes. Age (odds ratio [OR] = 1.10, 95% confidence interval [CI] 1.03-1.18) and ferritin level (OR 1.16, 95% CI 1.01-1.33) were associated with thalassemia-related retinal changes.

CONCLUSION

Novel retinal changes were observed in β-thalassemia major patients. This study identified older age and higher ferritin level as risk factors for thalassemia-related retinal changes.

Frequencies of Beta Thalassemia Mutations Show Different Pattern in Bannu Region than Other Parts of Pashtun Population in Khyber Pakhtunkhwa Province Pakistan

PURPOSE

β-Thalassemia arises as result of mutations in HBB gene, influencing the globin production which results in hypochromic and microcytic anaemia. The present study was aimed to investigate the occurrence of six common β-thal mutations, its inheritance pattern, frequency, and consanguinity in parents of Bannu region Khyber Pakhtunkhwa (KP) province, Pakistan. Conducting such studies may impart important information about thalassemia prevention like prenatal diagnosis (PND), carrier screening and genetic counselling which may be helpful in controlling the suspected births.

METHODS

During the study, 250 blood samples were retrieved from different families comprising of one transfusion dependent child and sporadic patients from different areas of Bannu region. The collected blood samples were investigated to see if there is any common mutations which may trigger β-Thalassemia employing amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) approach.

RESULTS

Amongst the studied mutation in District Bannu, frame shift codons (FSC) 8/9 (+ G) (HBB: c.27_28insG) was observed to be the most common mutation followed by Codons 41/42 (- TTCT), IVS-I-5(G > C) and FSC 5 (- CT) having frequencies of 42, 26, 19 and 13 respectively. The results obtained by the present study were found different from previous studies demonstrated from other Pashtun regions of KP, showing heterogeneity in frequencies of known mutations.

CONCLUSION

These observations may help in implementing parental meetings about disease recurrence in future, large scale mutation screening, and prenatal diagnosis in the whole Pashtun ethnicity including District Bannu.

Evaluation of the Significance of Tear Ferning Patterns in beta-Thalassemia Patients

AIM

This study was designed to evaluate the tear film in beta-thalassemia patients using tear ferning (TF) and phenol red thread (PRT) tests.

METHODS

Forty beta-thalassemia patients, aged 18 - 38 years (25.7 ± 6.0 years), along with a control group of 40 age-matched subjects with healthy eyes completed the study. All subjects completed the ocular surface disease index (OSDI) first, followed by the TF and PRT tests with a 5-minute gap between the tests.

RESULTS

Significant differences (Wilcoxon test, p < 0.05) were observed between the beta-thalassemia and control groups in all scores. Among beta-thalassemia patients, OSDI scores indicated eye dryness in 35 subjects (87.5%). PRT showed dryness in 31 subjects (77.5%) in the right and left eyes, and the TF grades were ≥ 2 for the tears collected from 35 subjects (87.5%). There was a strong correlation (r = 0.851, p = 0.001) between the PRT measurements in the right and left eyes. There was a medium correlation between OSDI and TF scores (r = 0.309, p = 0.026) and between OSDI and age (r = 0.365, p = 0.010). Age had a moderate negative correlation (r = - 0.328, p = 0.019) with the PRT obtained from the right eye.

CONCLUSION

Significant ocular dryness symptom was observed in beta-thalassemia patients, based on the scores collected from TF and PRT tests. Beta-thalassemia patients develop dry eyes, possibly due to several factors, including reduced tear secretion. Therefore, it is important to regularly evaluate both the quality and quantity of tears in patients with beta-thalassemia.

Ocular findings in patients with transfusion-dependent β-thalassemia in southern Iran

Background

Ocular involvement may occur via several mechanisms in patients with transfusion-dependent β-thalassemia (TDT) mainly chronic anemia, iron overload and iron chelator toxicity. We aimed to evaluate the frequency of abnormal ocular findings and their relationship with hematologic parameters in TDT patients.

Methods

In this cross-sectional study from January 2018 to January 2019, a total of 79 patients with TDT over the age of 18 who were on iron-chelation therapy (ICT) were consecutively investigated. All patients were registered at the Thalassemia Comprehensive Center affiliated with Shiraz University of Medical Sciences, Shiraz, Southern Iran. Complete ophthalmic examination was performed by an expert ophthalmologist. Clinical and hematologic parameters were collected from the patients´ medical records.

Results

The mean age ± standard deviation (SD) of the patients was 28.4 ± 5.6 years (range: 18–43). Twenty-four patients (30.4%) were male and 29 (36.7%) were splenectomized. The mean ± SD of the best-corrected visual acuity (VA) was 0.960 ± 0.086 decimal, (range: 0.6–1), 0.016 ± 0.046 logMar, (range: 0–0.2). The frequency of patients with VA > 0.1 logMar was 3 (3.8%). The mean intraocular pressure (IOP) was 14.88 ± 3.34 (6–25) mmHg. Fundus abnormalities were observed in 8 patients (10.1%), consisting of increased cup-disk ratio (3.8%), vessel tortuosity (2.5%), retinal pigment epithelium degeneration (2.5%), myelinated nerve fiber layer (1.3%), and internal limiting membrane wrinkling (1.3%). No significant association was observed between fundus abnormalities, VA, or IOP with hematologic parameters (P > 0.05). TDT patients with diabetes mellitus had significantly higher IOP (P = 0.010) but similar frequency of fundus abnormalities with non-diabetic patients (P > 0.05).

Conclusions

The frequency of ocular abnormalities in our patients was lower than the previous reports. The frequency of fundus abnormalities were similar in diabetic and non-diabetic thalassemia patients indicating close monitoring and proper management of the disease and comorbidities in these patients.

Optic disc drusen: a systematic review : Up-to-date and future perspective

BACKGROUND

Optic disc drusen (ODD) are acellular deposits in the prelaminar optic nerve head. The most accredited theory is that they are secondary to abnormalities in axonal metabolism and degeneration, but the pathogenesis is not clear to date.

CLINICAL MANIFESTATION

Although ODD are often considered a benign condition, the great majority of patients with ODD show visual field defects and are at higher risk for developing anterior ischemic optic neuropathy. ODD are classified as superficial or buried, with the latter being often misdiagnosed as papilledema with optic nerve head swelling, leading to an unnecessary investigation for causes of increased intracranial pressure.

AIM

The recent technological improvements in OCT imaging which allowed an earlier and more certain diagnosis even of the smallest ODD, renovated the interest around this pathology. However, an updated systematic review is still missing. Therefore, the aim of this work is to provide a concise yet comprehensive overview of the current state of art, focusing on pathophysiology, clinical presentation, diagnostic methods, treatment modalities and potential future perspectives of this condition.

The changing epidemiology of the ageing thalassaemia populations: A position statement of the Thalassaemia International Federation

Therapeutic advances in β-thalassaemia have gradually lead to a significant improvement in prognosis over the past few decades. As a result, patients living in areas where disease-specific programmes offering access to modern therapy are in place experience a new era of prolonged survival that tends to reach that of the normal population. This ageing thalassaemia population, however, faces a new spectrum of comorbidities resulting from increasing age that may jeopardise the advances in prognosis provided by current therapy and thus poses new challenges in diagnosis, monitoring and treatment. In this position paper of the Thalassaemia International Federation, we review the changing epidemiology and clinical spectrum of patients with β-thalassaemia and propose actions to be undertaken in order to address the emerging spectrum of comorbidities resulting from ageing.

Anterior Chamber Angle, Intraocular Pressure, and Globe Biometric Parameters in the Children with &beta;-Thalassemia Major

Background

To evaluate the intraocular pressure (IOP), anterior chamber angle (ACA), and globe biometric parameters in β-thalassemia major children and the correlations of these changes.

Materials and methods

Eighty-four eyes were included (42 eyes of thalassemia patients and 42 eyes of control). All participates underwent head circumference and height measurements, full ophthalmic examination, anterior segment optical coherence tomography (AS-OCT), and A-scan biometry.

Results

The temporal angle of anterior chamber (T-ACA) was significantly narrower in thalassemia patients with p value = 0.008. While the nasal angle showed a nonsignificant narrowing with p value = 0.153. This narrowing was positively correlated with the height, and negatively correlated with the head circumference. Intraocular pressure was statistically higher in thalassemia patients with p value = 0.000. The increased IOP was positively correlated with the head circumference and the lens thickness (LT) and negatively correlated with T-ACA, axial length (AL), vitreous chamber depth (VCD), and anterior chamber depth (ACD). Axial length, ACD, and VCD significantly decreased with p value = 0.000 for all with a positive correlation with the height and a negative correlation with the head circumference. The LT increased in thalassemia group with p value = 0.000. This increase was positively correlated with the head circumference and negatively with the height. Also, there was steeper corneal curvature in thalassemia group with p value = 0.023 and 0.015 (for K₁ and K₂, respectively). No significant change was observed in corneal thickness in both groups with p value = 0.810.

Conclusion

Narrower T-ACA, increased IOP, shorter (AL, VCD, and ACD), steeper corneal curvature, and thicker lens were found in thalassemia patients.

How to cite this article

El-Haddad NSM. Anterior Chamber Angle, Intraocular Pressure, and Globe Biometric Parameters in the Children with β-Thalassemia Major. J Curr Glaucoma Pract 2020;14(1):30–36.

Molecular Heterogeneity of β-Thalassemia in the Kohat Region, Khyber Pakhtunkhwa Province, Pakistan

The present study was intended to report the incidence of the most frequently occurring β-thalassemia (β-thal) mutations in the Kohat region [Khyber Pakhtunkhwa (KP) Province, Pakistan], their inheritance pattern in patients, and consanguinity in the parents. Moreover, this study could provide valuable information regarding thalassemia diagnoses such as prenatal diagnosis (PND), genetic counseling and carrier screening for controlling the affected births in the population. During this study, 160 peripheral blood samples of affected patients, their parents and siblings were collected from 25 discrete families having at least one child needing regular blood transfusions from different areas of the Kohat region. β-Thalassemia mutations found in the population were screened via the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). A total of 320 alleles was evaluated for the presence of six β-thal mutations. Of these six β-thal mutations, the frameshift codons (FSC) 8/9 (+G) (HBB: c.27_28insG) was found to be the most frequent in the studied population, and more interestingly, followed by IVS-I-5 (G>C) (HBB: c.92+5G>C) and FSC 5 (-CT) (HBB: c.17_18delCT). The findings of the present study show differences with previous results from other regions of the Pashtun population, which demarcates the heterogeneity in mutations found in the Pashtun ethnicity. These observations may help in implementing parental meetings about disease recurrence in future, large scale mutation screening and PND for the population of the Kohat region and also the whole Pashtun ethnicity.

A Pilot Optical Coherence Tomography Angiography Study on Superficial and Deep Capillary Plexus Foveal Avascular Zone in Patients With Beta-Thalassemia Major

Purpose

To investigate foveal avascular zone (FAZ) changes in the superficial (SCP) and deep (DCP) capillary plexuses in beta-thalassemia major (BTM) patients, as shown in optical coherence tomography angiography.

Methods

Nonrandomized, comparative case series of 54 eyes of 27 BTM patients and 46 eyes of 23 healthy controls, utilizing an automated FAZ detection algorithm. Measurements included FAZ area and FAZ shape descriptors (convexity, circularity, and contour temperature). Results were compared between the two groups, and correlated to iron load and chelation therapy parameters.

Results

SCP and DCP FAZ area were not significantly different between the control and BTM groups (P = 0.778 and P = 0.408, respectively). The same was true regarding SCP FAZ convexity (P = 0.946), circularity (P = 0.838), and contour temperature (P = 0.907). In contrast, a statistically significant difference was detected between controls and BTM group regarding DCP FAZ convexity (P = 0.013), circularity (P = 0.010), and contour temperature (P = 0.014). Desferrioxamine dosage was strongly correlated to the DCP area (r = 0.650, P = 0.05) and liver magnetic resonance imaging/T2-star to DCP circularity (r = -0.492, P = 0.038). Correlations were also revealed between urine Fe excretion and DCP convexity (r = 0.531, P = 0.019), circularity (r = 0.661, P = 0.002), and contour temperature (r = -0.591, P = 0.008).

Conclusions

Retinal capillary plexuses and especially DCP seem to present unique morphologic changes in BTM patients, not in the FAZ area, but in specific shape descriptors, indicating minor but detectable FAZ changes. These changes correlate well with iron load and chelation therapy parameters. Their clinical importance and pathophysiologic implications remain to be elucidated through further studies.

Consanguineous unions and endogamy in families of beta-thalassaemia patients from two Mediterranean populations: Tunisia and Italy

Background: Consanguinity increases the incidence of recessive diseases such as beta-thalassaemia major (βTM), one of the most prevalent lethal inherited diseases in the world.Aim: This study aims to identify the frequency of endogamy and consanguinity in two Mediterranean βTM populations and to study the implication of socio-economic factors.Subjects and methods: A trans-sectional study was conducted in 203 Tunisian families and 75 Italian families. Data were collected using a questionnaire completed by patients and parents.Results: Complete endogamy and consanguinity were observed in 82.75% and 62.56% of Tunisian families, respectively. Complete endogamy was found in 90.67% of Italian families, no consanguinity was noted. The low occupation status of Tunisian mothers was associated with an increasing frequency of consanguinity (p = .01) and endogamy (p = .0003). Consanguinity was associated with low education level (p = .012) and low occupation status (p=.047) of fathers. No significant association was found between endogamy and socio-economic factors in the Italian sample.Conclusions: High consanguinity and endogamy rates in Tunisian families may explain the frequency of βTM in Tunisia. The high endogamy rate in Italian families could also increase the frequency of βTM. Identification of geographical distribution and socio-economic factors leading to endogamy and consanguinity in these populations might help to improve βTM prevention.

T2 ∗ Relaxation Time Obtained from Magnetic Resonance Imaging of the Liver Is a Useful Parameter for Use in the Construction of a Murine Model of Iron Overload

Aim

Iron overload is a life-threatening disorder that can increase the risks of cancer, cardiovascular disease, and liver cirrhosis. There is also a risk of iron overload in patients with chronic kidney disease. In patients with renal failure, iron storage is increased due to inadequate iron utilization associated with decreased erythropoiesis and also to the inflammatory status. To evade the risk of iron overload, an accurate and versatile indicator of body iron storage in patients with iron overload is needed. In this study, we aimed to find useful iron-related parameters that could accurately reflect body iron storage in mice in order to construct a murine model of iron overload.

Methods

To select an appropriate indicator of body iron status, a variety of parameters involved in iron metabolism were evaluated. Noninvasively measured parameters were R1, R2, and R2^∗ derived from magnetic resonance imaging (MRI). Invasively measured parameters included serum hepcidin levels, serum ferritin levels, and liver iron contents. Histopathological analysis was also conducted.

Results/Conclusion

Among the several parameters evaluated, the MRI T2^∗ relaxation time was able to detect iron storage in the liver as sensitively as serum ferritin levels. Moreover, it is expected that using an MRI parameter will allow accurate evaluation of body iron storage in mice over time.

Ocular abnormalities in beta thalassemia patients: prevalence, impact, and management strategies

BACKGROUND

Beta thalassemia (β-thalassemia) is a hereditary disease caused by defective globin synthesis and can be classified into three categories of minor (β-TMi), intermedia (β-TI), and major (β-TM) thalassemia. The aim of our study is to investigate the effects of β-thalassemia and its treatment methods on different parts of the eye and how early-diagnostic methods of ocular complications in this disorder would prevent further ocular complications in these patients by immediate treatment and diet change.

METHODS

We developed a search strategy using a combination of the words Beta thalassemia, Ocular abnormalities, Iron overload, chelation therapy to identify all articles from PubMed, Web of Science, Scopus, and Google Scholar up to December 2018. To find more articles and to ensure that databases were thoroughly searched, the reference lists of selected articles were also reviewed.

RESULTS

Complications such as retinopathy, crystalline lens opacification, color vision deficiency, nyctalopia, depressed visual field, reduced visual acuity, reduced contrast sensitivity, amplitude reduction in a-wave and b-wave in Electroretinography (ERG), and decrease in the Arden ratio in Electrooculography (EOG) have all been reported in β-thalassemia patients undergoing chelation therapy.

CONCLUSION

Ocular problems due to β-thalassemia may be a result of anemia, iron overload in the body tissue, side effects of iron chelators, and the complications of orbital bone marrow expansion.

Optic Nerve Head Drusen: An Update

Optic nerve head drusen are benign acellular calcium concretions that usually form early in life, just anterior to the lamina cribrosa. Improving imaging using optical coherence tomography suggests they are common and may be present in many clinically normal discs. These drusen may change in appearance in early life, but are generally stable in adulthood, and may be associated with visual field defects, anterior ischaemic optic neuropathy, or rarer complications. Based on long-term clinical data and optical coherence tomography, we propose a refined hypothesis as to the cause of optic disc drusen. Here we summarise recent findings and suggest future studies to better understand the forces involved.

Raman characterizations of red blood cells with β-thalassemia using laser tweezers Raman spectroscopy

This study aimed to study the differences in Raman spectra of red blood cells (RBCs) among patients with β-thalassemia and controls using laser tweezers Raman spectroscopy (LTRS) system.A total of 33 patients with β-thalassemia major, 49 with β-thalassemia minor, and 65 controls were studied. Raman spectra of RBCs for each sample were recorded. Principal component analysis (PCA), one-way analysis of variance (ANOVA), and independent-sample t test were performed.The intensities of Raman spectra of β-thalassemia (major and minor) RBCs were lower than those of controls, especially at bands 1546, 1603, and 1619 cm. The intensity ratio of band 1546 cm to band 1448 cm demonstrated that there was a significant difference between the spectra of β-thalassemia major (mostly below 2.15) and those of controls. The spectra of controls could be well distinguished from those of β-thalassemia major using PCA. After normalization, the spectra of two different genotypes with β/β mutations mainly overlapped, while those with β/β mutations had lower intensity at bands 1546, 1603, and 1619 cm.The present study provided Raman characteristics of RBCs in patients with β-thalassemia major and supported the use of LTRS as a method for screening β-thalassemia major. The recognition rate for β-thalassemia minor needs to be further improved.

Effect of serum fibroblast growth factor receptor 2 and CAPS proteins on calcium status in β-thalassaemia major patients who are free from overt inflammation

Bone disorders and disturbed calcium (Ca) homeostasis are common disorders in β-thalassaemia major (β-TM). In the present study, two bone related markers are studied in β-TM patients with negative C-reactive protein for the first time; fibroblast growth factor receptor 2 (FGFR2) and CAPS protein. Another goal is to estimate the correlation between the recent parameters and bone biomaterials as a function of iron status parameters in β-TM patients. The results revealed that, in patients with β-TM serum FGFR2, CAPS, alkaline phosphatase (ALP) and Mg significantly increased while serum Ca levels were low as compared with controls. Ca status is correlated with iron overload in β-TM. A significant correlation was present between CAPS and FGFR2. In conclusion, FGFR2 and CAPS associated with Ca status and subsequent bone disturbances in β-TM patients. Their level can be predicted from the equation: CAPS =0.001ALP +0.48FGFR2-1.26Ca - 3.95Pi +12.76 with acceptable applicability.

Deferoxamine-induced electronegative ERG responses

PURPOSE

To report a case of deferoxamine-induced retinopathy characterized by electroretinography (ERG), optical coherence tomography angiography (OCT-A), and other multimodal imaging.

METHODS

This is an observational case report of one patient. Full-field ERG was performed. OCT-A, spectral-domain optical coherence tomography (SD-OCT), color fundus photography, and fundus autofluorescence were used to characterize the retinopathy induced by deferoxamine use.

RESULTS

A 64-year-old man with a history of β-thalassemia intermedia presented with worsening visual acuity, nyctalopia, and electronegative ERG. OCT-A revealed atrophy of the choriocapillaris in areas of hypoautofluorescence, corresponding to regions of retinal atrophy. SD-OCT showed disruption of the ellipsoid zone, granular hyperreflective deposits within the retinal pigment epithelium, thinning of the retinal layers, and extensive choroidal sclerosis and atrophy of the retinal pigment epithelium.

CONCLUSION

Deferoxamine-induced retinopathy can manifest with electronegative maximal ERG responses, and OCT-A can be used to detect deferoxamine toxicity.

Molecular characterization of α- and β-thalassemia in the Yulin region of Southern China

Thalassemia is one of the most common hereditary blood disorders. Epidemiological data regarding the prevalence and distribution of mutations is important for planning a thalassemia control program. To reveal the prevalence of thalassemia and mutation spectrum in the Yulin region of southern China, we screened 130,318 individuals from Yulin region by hematological and genetic analysis. Totally, 24,886 (19.10%) subjects were diagnosed with thalassemia, including 16,308 (12.51%) subjects with α-thalassemia alone, 6658 (5.11%) subjects with β-thalassemia alone and 1920 (1.47%) subjects with both α- and β-thalassemia. Ten α-thalassemia mutations were identified in the α-thalassemia subjects, with the common α-thalassemia mutations being --^SEA mutation (51.91%), -α^3.7 (19.90%), α^CSα (10.58%), -α^4.2 (8.13%), α^WSα (7.67%). Thirteen β-thalassemia mutations and 31 genotypes were characterized in the β-thalassemia subjects. The seven common mutations [CD41-42 (-CTTT) (43.31%), CD17 (A > T) (34.58%), CD26 (G > A) (6.86%), CD71-72 (+A) (4.25%), -28 (A > G) (3.90%), IVS-II-654 (C > T) (3.53%) and IVS-I-1 (G > T) (2.22%)] accounted for 98.65% of all β-thalassemia defects. Furthermore, 6 cases of α-triplication and 3 cases of mutation -α^2.4 were first identified in this region. Our data illustrated that there was great heterogeneity and extensive spectrum of thalassemias in the Yulin populations. The findings will contribute an available reference for prevention of thalassemia in this region.

[Management of patients with major beta thalassemia in a paediatric department in the south of Tunisia: About 26 cases]

AIM

Our objectives were to assess the management of patients with major thalassemia and identify the various complications and monitoring means.

PATIENTS AND METHODS

A retrospective study was conducted on 26 β-thalassemic patients in the department of paediatrics, Hédi Chaker hospital, Sfax, Tunisia during a period of 25 years (from 1 January 1990 to 31 December 2014).

RESULTS

The mean age of the beginning of transfusion was 11.5 months. That was with phenotyped red blood cells but not leukodepleted blood. Twenty-three patients received chelation. Before 2001, all patients received deferoxamine, poor adherence to this treatment was observed in 66% of cases. It was replaced by deferiprone since 2006 and deferasirox since 2009. A combination of 2 or 3 chelators was indicated for four patients. A total splenectomy was performed in 10 cases patients; it was due to hypersplenism. The bone marrow transplant was performed for one patient at the age of 9 year but it was rejected. Many complications were detected: endocrine complications (19 cases), immune complications (9 cases), gallbladder stones (5 cases), cardiac complications (4 cases), osteoporosis (3 cases), infectious complications (3 cases) and thromboembolic complications (2 cases). We noted some side effects related to chelation therapy in twelve cases. Four patients were dead.

CONCLUSION

Improving the medical care of homozygous β-thalassemic children requires adherence to transfusion regimen and chelation therapy. Bone marrow transplantation remains the only possible curative therapy, which must be promoted in our country.