Myasthenia gravis symptom response to huperzine A, pyridostigmine bromide, and an immunomodulatory incorporated regimen: A multi-case study

Myasthenia gravis: do not forget the patient perspective

Objectives We have characterised the population pharmacokinetics-pharmacodynamics of pyridostigmine given as pyridostigmine bromide. Methods Over three days 50 healthy Chinese male subjects each received seven doses of 30 mg pyridostigmine bromide orally (3 times 10 mg every 8 h). Plasma concentrations of pyridostigmine and red blood cell acetylcholinesterase (AChE) activity were determined at various times within the eight hours after the first and the seventh doses. The resulting pharmacokinetic data were fitted to a single compartment open model with first-order absorption and elimination. The pharmacodynamics were modelled using an inhibitory Emax model. The potential influence of demographic and biological covariates on the model parameters was investigated. Nonlinear mixed effects modelling was performed using NONMEM. Key findings The apparent clearance and volume of distribution as well as absorption rate constant of plasma pyridostigmine were estimated to be 136 1/h, 130 1 and 0.68 1/h, respectively. The maximum red blood cell AChE activity decrease (Emax) and plasma pyridostigmine concentration producing 50% of this reduction (EC50) were estimated to be 9.32 AChE units per gram haemoglobin and 51.9 ng/ml, respectively. None of the tested covariates were found to be correlated with any of the model parameters. Dosing simulations suggested that 30 mg repeated every six hours might be needed to achieve steady-state trough percentage inhibition above the recommended 10% in healthy Chinese males. Conclusions The pharmacokinetics and the effects of pyridostigmine on red blood cell AChE activity were described using a mixed effects model. For Chinese males, the dosing interval may have been shorter than that recommended for the Caucasian population. Additional studies are needed to confirm these findings.

We have characterised the population pharmacokinetics-pharmacodynamics of pyridostigmine given as pyridostigmine bromide. Over three days 50 healthy Chinese male subjects each received seven doses of 30 mg pyridostigmine bromide orally (3 x 10 mg every 8 h). Plasma concentrations of pyridostigmine and red blood cell acetylcholinesterase (AChE) activity were determined at various times within the eight hours after the first and the seventh doses. The resulting pharmacokinetic data were fitted to a single compartment open model with first-order absorption and elimination. The pharmacodynamics were modelled using an inhibitory E(max) model. The potential influence of demographic and biological covariates on the model parameters was investigated. Nonlinear mixed effects modelling was performed using NONMEM. The apparent clearance and volume of distribution as well as absorption rate constant of plasma pyridostigmine were estimated to be 136 l/h, 130 l and 0.68 1/h, respectively. The maximum red blood cell AChE activity decrease (E(max)) and plasma pyridostigmine concentration producing 50% of this reduction (EC50) were estimated to be 9.32 AChE units per gram haemoglobin and 51.9 ng/ml, respectively. None of the tested covariates were found to be correlated with any of the model parameters. Dosing simulations suggested that 30 mg repeated every six hours might be needed to achieve steady-state trough percentage inhibition above the recommended 10% in healthy Chinese males. The pharmacokinetics and the effects of pyridostigmine on red blood cell AChE activity were described using a mixed effects model. For Chinese males, the dosing interval may have been shorter than that recommended for the Caucasian population. Additional studies are needed to confirm these findings.

Sarin gas attack caused by AUM SHINRIKYO, Japanese cult, gave us great shock toward illegal usage of chemical warfare agent. Eighteen people died and more than fifty hundreds had received medical treatment, in Matsumoto Incident (June 27, 1994) and in Tokyo Subway Incident (March 20, 1995). We have performed toxicological tests for the blood samples drawn from 7 (Matsumoto) and 11 (Tokyo) dead and 38 (Matsumoto) injured people. Both red blood cell (RBC) acetylcholinesterase (AChE) and plasma butyrylcholinesterase (BuChE) activities of victim’s blood samples have been measured by modified Ellman’s method using specific substrates acetylthiocholine and butyrylthiocholine, respectively. Compared to the control values of healthy donors, both RBC AChE and plasma BuChE activities were significantly (p<0.05) lowered in 7 fatalities and 16 nonfatal casualties in Matsumoto and 6 fatalities in Tokyo. The extent of the lowered activity levels was more remarkable in RBC AChE than in plasma BuChE. There were one fatal and 9 nonfatal casualties which RBC AChE activities were significantly lowered even though the counterpart plasma BuChE activities were not lowered.

Evidence for a Central Cholinergic Deficit in Myasthenia Gravis

We investigated the red blood cell (RBC) acetylcholinesterase (AChE) activities and butyrylcholinesterase (BChE) activities at presentation to the emergency department (ED) and at 24 h after presentation following poisoning by dichlorvos, fenitrothion, or ethyl p-nitrophenol thio-benzene phosphonate (EPN). Although the patients from different groups had similar characteristics at presentation such as time interval from ingestion to presentation to the ED and the amount of organophosphate ingested, the dichlorvos group had significantly lower BChE levels than the fenitrothion group and lower RBC cholinesterase activity than the EPN group. Patients poisoned with EPN or dichlorvos had significantly higher inhibition of BChE activities from baseline than RBC AChE activities at presentation. Twenty four hours after administration of pralidoxime, RBC AChE activities had increased in patients in the dichlorvos and EPN groups, while RBC AChE activities had slightly decreased in the fenitrothion group. BChE activities increased significantly in the dichlorvos group but decreased in the EPN group. The recovery patterns of RBC AChE and BChE activities did not match in any particular individual. This study showed that the patterns of inhibition and recovery of the activities of two cholinesterases after treatment are highly variable according to the organophosphate and in different individuals.

Increased Toll-Like Receptor 4 Expression in Thymus of Myasthenic Patients with Thymitis and Thymic Involution

Objective To explore the relationships among hope level, coping style and quality of life (QOL) in myasthenia gravis (MG) patients. Methods From September 2016 to September 2017, 139 MG patients of Shaoxing People's Hospital were selected by convenience sampling. The hope level, coping style and QOL of patients were investigated with the Herth Hope Index (HHI) , Medical Coping Modes Questionnaire (MCMQ) and Quality of Life Questionnaire-Core 30 (QLQ-C30) . Pearson correlation and multiple linear regression were used to analyze the correlations among them and influencing factors of QOL respectively. Results The total score of HHI, score of confrontation dimension, avoidance dimension, yield dimension of MCMQ and score of total QOL of MG patients was (35.85±3.14) , (18.78±3.67) , (15.82±2.37) , (9.94±2.79) and (52.33±11.83) respectively. Correlation analysis showed the total score of HHI of MG patients was positively associated with the total score of total QOL (r=0.675, P<0.05) ; the confrontation coping style was positively associated with the total QOL (r=0.613, P<0.05) ; the yield coping style had a negative correlation with the total QOL (r=-0.582, P<0.05) . Multiple linear regression analysis revealed the influencing factors of QOL of MG patients included the burden of medical expense, classification of Myasthenia Gravis Foundation of America (MGFA) , total score of HHI and yield. Conclusions The QOL of MG patients is in a low level. The main influencing factors of QOL of patients involve the burden of medical expense, classification of MGFA, hope level and yield coping style. Key words: Myasthenia gravis; Quality of life; Level of hope; Coping style

BackgroundAssessment of acetylcholinesterase-inhibitor insecticide (AChEII) toxicity depends on the measurement of red blood cell acetylcholinesterase (RBC-AChE) activity. Its interpretation requires baseline values which is lacking in scientific literature. We aim to find the measures of central tendency and variation for RBC-AChE activity among dwellers of Anuradhapura, where the use and abuse of AChEIIs were rampant for the last few decades.MethodsA descriptive cross-sectional study with a community-based sampling for 100 healthy non-farmers (male:female = 1:1) was done using pre-determined selection criteria. Duplicate measurements of RBC-AChE activity were performed according to the modified Ellman procedure. Pearson’s correlation and regression analysis were sort for RBC-AChE activity against its possible determinants.ResultsRBC-AChE activity had a mean of 449.8 (SD 74.2) mU/μM Hb with a statistical power of 0.847. It was similar to values of “healthy controls” from previous Sri Lankan toxicological studies but was low against international reference value [586.1 (SD 65.1) mU/μM Hb]. None of the possible determinants showed a significant strength of relationship with RBC-AChE activity.ConclusionThe baseline RBC-AChE activity among people of Anuradhapura is low in comparison with international reference values. This arises a need to find a causative mechanism.

PurposeWith the adjustment of prevention strategies in December 2022, coronavirus disease 2019 (COVID-19) became widely prevalent in China. This study is aimed to describe the clinical characteristics of myasthenia gravis (MG) patients with COVID-19 and identify risk factors of exacerbation in MG patients with COVID-19 in Guangxi.Patients and MethodsA total of 489 MG patients and 587 control subjects in Guangxi during the COVID-19 pandemic were enrolled in this case–control study. After contacting the participants, the clinical data of MG patients and the control group were analyzed. The clinical characteristics of MG patients with COVID-19 were described. Multivariable logistic regression analysis was used for discovering independent risk factors of MG exacerbation in the patients with MG and COVID-19.ResultsA total of 311 (75.30%) MG patients and 428 (72.91%) control subjects were infected with COVID-19, and 64.31% of MG patients with COVID-19 were women. The median age at the time of interview was 41 (IQR: 28, 54) years old, and median onset age was 36 (IQR: 24, 51), both of which were lower than those in MG patients without COVID-19. MG duration was 24 (IQR: 9, 72) months. About 44.69% of patients were generalized MG (GMG). About 11.90% of MG patients with COVID-19 showed severe COVID-19 symptoms and the duration of symptomatic COVID-19 was 9.57 ± 6.79 days, higher than those in the control group. About 35.69% MG patients with immunosuppressive drugs were infected with COVID-19, which is higher than those in the non-infected MG patients (21.57%). A total of 120 (38.59%) MG patients with COVID-19 had comorbidities. About 21 (20.19%) of the 104 MG patients without vaccination showed severe COVID-19 symptoms. Multivariable logistic regression analysis showed that baseline MG activities of daily living profile (MG-ADL, OR 1.280, 95% CI: 1.010–1.621, p = 0.041), duration of COVID-19 (OR 1.158, 95% CI: 1.100–1.220, p < 0.001), GMG (OR 2.331, 95% CI: 1.228, 4.426, p = 0.010), and lack of COVID vaccination (OR 2.075, 95% CI: 1.152, 3.738, p = 0.015) were independent factors of exacerbation in MG patients with COVID-19.ConclusionMG patients with immunosuppressive drugs, younger onset, longer MG duration, or comorbidities are more susceptible to COVID-19. The baseline MG-ADL, duration of symptomatic COVID-19, GMG, and lack of COVID-19 vaccination are independent risk factors of exacerbation in MG patients with COVID-19.

Background and PurposeAcetylcholinesterase inhibitors (AChEIs) are widely used to treat myasthenia gravis (MG). Although AChEIs are usually tolerated well, some MG patients suffer from side effects. Furthermore, a small proportion of MG patients show cholinergic hypersensitivity and cannot tolerate AChEIs. Because repetitive compound muscle action potentials (R-CMAPs) are an electrophysiologic feature of cholinergic neuromuscular hyperactivity, we investigated the clinical characteristics of MG patients with R-CMAPs to identify their clinical usefulness in therapeutic decision-making.MethodsWe retrospectively reviewed the clinical records and electrodiagnostic findings of MG patients who underwent electrodiagnostic studies and diagnostic neostigmine testing (NT).ResultsAmong 71 MG patients, 9 could not tolerate oral pyridostigmine bromide (PB) and 17 experienced side effects of PB. R-CMAPs developed in 24 patients after NT. The highest daily dose of PB was lower in the patients with R-CMAPs (240 mg/day vs. 480 mg/day, p<0.001). The frequencies of PB intolerance and side effects were higher in the patients with R-CMAPs than in those without R-CMAPs [37.5% vs. 0% (p<0.001) and 45.8% vs. 12.8% (p=0.002), respectively]. The MG Foundation of America postintervention status did not differ significantly between MG patients with and without R-CMAPs, and the response to immunotherapy was also good in both groups.ConclusionsSide effects of and intolerance to AChEIs are more common in MG patients with R-CMAPs than in those without R-CMAPs. AChEIs should be used carefully in MG patients with R-CMAPs. The presence of R-CMAPs after NT may be a good indicator of the risks of PB side effects and intolerance.

Introduction Different autoimmune conditions have been described in human immunodeficiency virus (HIV) patients on antiretroviral therapy (ART), but muscle-specific kinase (MuSK) myasthenia gravis (MG) coexisting with HIV is rare. We report a case of a Chinese patient with an asymptomatic HIV infection who presented with newly-onset MuSK MG and was managed successfully with the acetylcholinesterase inhibitor pyridostigmine. Case report A 71-year-old Chinese male from Zhejiang province had an established HIV infection and was on ART since 2014. He presented to the outpatient clinic stating that for the last 5 days he had been experiencing double ptosis, weakness in the neck, and difficulty to hold up his head, which were all worsening in the evening. He had been on ART consisting of Zidovudine 300 mg BID, Lamivudine 300 mg QD, and Nevirapine 200 mg BID. Although he was diagnosed and started on ART in 2014, he was subsequently followed up and had undetected viral loads with CD4 counts of 100–150 cells/μL in 2017. So, the highly active antiretroviral therapy (HAART) was changed in October 2017, and subsequently consisted of Tenofovir 300 mg QD, Lamivudine 300 mg QD, and Efavirenz 600 mg QD. His CD4 counts had increased to 183 cells/μL by April 2018. He had hypertension since 1999 and was treated with L-amlodipine and irbesartan. He had type 2 diabetes since 1999 and was treated with insulin aspartate and insulin glargine. Review of other systems was negative. On examination, he had bilateral ptosis with serious left ptosis covering the inferior margin of the pupil, and cervical extensors were at 4-strength. Fatigue tests of bilateral palpebral muscles were positive and the bilateral tendon reflex was positive. Other cranial nerves were intact. Motor, sensory, coordination, and other deep-tendon reflexes were normal. Routine blood tests, creatinine kinase, anti-nuclear antibody, anti-neutrophil cytoplasmic antibodies, rheumatoid factor, thyroid function, and anti-thyroid antibodies were normal. Total IgG titers were mildly elevated (1878 mg/dL, reference range 800–1800 mg/dL, and IgA, IgM, C3, and C4 were within normal limits. Hepatitis C antibodies were negative. Brain magnetic resonance imaging did not show any neurological abnormalities and computerized tomographic scanning of the chest did not show any significant enlargement of the thymus. His acetylcholine receptor (AChR) antibodies were negative, while MuSK antibodies were 12.00 U/mL (MuSK autoantibody titer along with cutoff 0.40 U/mL). Repetitive nerve stimulation tests (3 Hz) showed normal findings. He received oral pyridostigmine therapy (360 mg daily) soon after diagnosis of MuSK antibody-positive MG in September 2018, which resulted in resolution of ptosis and bulbar symptoms and incomplete improvement of neck weakness. However, he experienced double ptosis and weakness in the neck again when pyridostigmine was reduced to a daily dosage of 180 mg in February 2019. So, the dose of oral pyridostigmine was reduced slowly and he responded to oral pyridostigmine therapy with daily dosages of 240–180 mg from February to June 2019. By July 2019, all his symptoms had improved dramatically and pyridostigmine was stopped. He experienced continuous improvement of CD4+ T cells (202 cells/μL) with undetectable HIV viral loads. Up to January 2020, none of his symptoms reappeared. Discussion MG is an autoimmune disease that is associated with antibodies affecting the postsynaptic membrane at the neuromuscular junction.1,2 80% of MG patients have detectable antibodies against AChR, while a minority has antibodies against MuSK and lipoprotein-receptor-related protein 4.2 Overall, 1%–10% of the MG patients have serum MuSK antibodies.1 MuSK is a protein expressed in the postsynaptic muscle membrane and linked to AChR to maintain AChR function. MuSK MG is estimated to have a prevalence of 2.9 per million people in Europe.3 In China, MuSK MG is more common in the north.4 Although MG is one of the best-characterized and understood autoimmune disorders, comorbidity of HIV and MG is rare and mostly reported in incidental case reports.5 Hung et al.6 previously summarized the common characteristics of these comorbid HIV and MG patients: (1) MG develops in the early stage of HIV infection when the immune system is relatively intact; (2) the clinical course of MG appears to be benign and most patients show improvements along with advancing immunodeficiency; (3) serum anti-AChR antibodies are absent or show low titers; (4) there is little association of thymus hyperplasia as opposed to patients with AChR-Ab-positive myasthenia. Clinical features of MuSK MG resemble AChR-Ab MG, but MuSK MG patients show predominant involvement of cranial and bulbar muscles with increased incidence of ptosis, diplopia, and dysarthria, prominent with neck and respiratory muscle involvement and are less responsive to acetylcholinesterase inhibitors.7 MuSK MG may have a different cause and pathologic mechanism compared with AChR-Ab-positive MG.1,2 Comorbidity of HIV and MuSK MG is very rare, with only five cases previously reported, and very little is known about this association.8–12 These cases are summarized in Table 1. Among them, two are African Americans, while the other three are African, Japanese, and someone from Thailand. In our case, the MuSK MG patient with HIV infection came from Zhejiang province, in the south of China. One case report showed no MG relapse in an HIV-infected patient who was successfully treated with efavirenz-containing therapy.13 However, our patient, who was on Efavirenz-containing HAART, was just being diagnosed with MuSK MG. All these five case reports have described MuSK MG in HIV as part of immune reconstitution after antiretroviral treatment, in which MG was manifested as CD4 counts improved after HAART.8–12 A similar pattern was seen in the presentation of our patient, in whom the improvement of CD4 counts with changes of antiretroviral drug led to presentation of the symptoms. The following improvement of MG was accompanied with increasing CD4+ T cell counts. A consistent finding in patients with MuSK MG is that they have a much lower frequency of thymic pathology than patients with AChR-Ab-positive MG.14 This finding is consistent in all the aforementioned cases summarized in Table 1, including our patient. A possible explanation might be the normalization of immune regulation and the remount of CD4+ suppressor-inducer or regulatory T cells.Table 1: Comparison of case reports on MuSK myasthenia gravis and HIV.The management of patients with both HIV and MuSK MG is challenging. Immunosuppressants and immunomodulators have been used for the treatment of MuSK MG in HIV patient based on case reports, and was not entirely without risk.8–12 All of the five reported cases listed in Table 1 had similar findings along with positive MuSK antibodies and were subsequently treated with immunomodulators like cyclosporine, intravenous immunoglobulin, azathioprine, rituximab, and plasma exchange. Different from other cases of MG with worsening symptoms, our patient was managed with the acetylcholinesterase inhibitor pyridostigmine, which improved his symptoms successfully. Therefore, due to the lack of studies on treatment of MuSK MG in HIV patients, the use of steroids and immunomodulators should be cautiously evaluated in each patient. In conclusion, we propose that the relationship between HIV infection and MuSK MG is not just a coincidence. The Chinese old man with an established HIV infection developed new-onset MuSK MG when he was on Efavirenz-containing HAART. The improvement of MG was actually accompanied with increasing CD4+ T cell counts after changes of prescribed antiretroviral drugs and MG was successfully managed with the acetylcholinesterase inhibitor pyridostigmine. Further research is needed to identify the underlying immuno-pathogenesis and to prevent and treat MuSK MG in HIV patients.

Background A previous study on thymomas in myasthenia gravis (MG) patients indicated that OX40 expression may be upregulated in thymic tissues adjacent to germinal centers (GCs) and thymomas, and OX40 may interact with OX40L in GCs to enhance anti-acetylcholine receptor antibody production. However, little is known about the clinical significance of the expression of OX40 and OX40L in the peripheral blood of patients with MG. We aimed to characterize the expression of membrane-bound and soluble OX40 and OX40L in the peripheral blood of patients with MG and to identify their clinical significance. Methods For membrane molecules, we collected peripheral blood (PB) from 39 MG patients at baseline, 22 patients in relapse, and 42 patients in remission, as well as from 36 healthy participants as controls. For soluble molecules, plasma from 37 MG patients at baseline, 34 patients in relapse, and 30 patients in remission, as well as plasma from 36 healthy controls (HC), was retrospectively collected from the sample bank of the First Hospital of Soochow University. The expression of membrane-bound OX40 and OX40L (mOX40 and mOX40L) by immune cells was measured using flow cytometry. Plasma levels of soluble OX40 and OX40L (sOX40 and sOX40L) were measured by ELISA. Results (1) The expression of OX40 on CD4+ T cells and that of OX40L on B cells and monocytes were significantly increased, and the levels of sOX40 were significantly decreased in MG patients at baseline compared with HC, while the expression of sOX40L was not significantly different between the two groups. (2) Dynamic observation of the molecules showed significantly higher expression of OX40 on CD4+ T cells and higher levels of sOX40 in MG patients in relapse than in MG patients at baseline and MG patients in remission. Furthermore, the expression levels of sOX40 were significantly elevated in MG patients in remission compared with MG patients at baseline, and the expression of sOX40L was significantly lower in MG patients in remission than in MG patients at baseline and MG patients in relapse. (3) Plasma levels of sOX40 and sOX40L were significantly decreased in 13 patients with relapsed MG after immunosuppressive treatment compared with those before treatment. (4) Correlation analysis showed that the expression of OX40 on CD4+ T cells in patients with relapsed MG was positively correlated with the concentration of acetylcholine receptor antibodies (AchR-Ab), whereas the expression of OX40L on CD19+ B cells and CD14+ monocytes was negatively correlated with disease duration. (5) Binary regression analysis showed that patients with high CD4+ OX40 expression and high sOX40L levels had an increased risk of relapse. Conclusions OX40 and OX40L are abnormally expressed in the peripheral blood of patients with MG and may be closely associated with disease status and treatment. The OX40/OX40L pathway may be involved in the immunopathological process of MG and may play a role mainly in the later stage of MG.

Objective To analyze the clinical characteristics, drug efficacy and prognosis of patients with myasthenia gravis (MG) associated with other autoimmune diseases. Methods Eighty-three MG patients were divided into 2 groups. One group included MG patients with autoimmune diseases (AIDMG, N = 24), and the other included MG patients without autoimmune diseases (NAIDMG, N = 59). Firstly, clinical features such as sex, age of onset, initial symptoms and thymus abnormalities were compared between patients with AIDMG and NAIDMG. Secondly, effect of different therapies, including pyridostigmine, corticosteroids, immunoglobulin, immunosuppressants and thymectomy was compared between 2 groups. Finally, prognosis including relapse rate and recurrence time during the first 2 years after MG onset was compared. Whether and when ocular myasthenia gravis (OMG) progressing to general myasthenia gravis (GMG) and the first onset of GMG symptoms during the first 2 years were also compared between 2 groups. Results The difference of gender predominance ( χ 2 = 8.467, P = 0.004), ptosis affecting left or right or both sides ( χ 2 = 9.830, P = 0.007) and disease course within 2 years after onset ( χ 2 = 15.255, P = 0.001) between AIDMG group and NAIDMG group were statistically significant. Other clinical features such as age of onset ( χ 2 = 1.728, P = 0.228), initial symptoms ( χ 2 = 0.252, P = 0.791), thymus abnormalities ( χ 2 = 3.200, P = 0.202) were not significantly different between 2 groups. Differences of therapeutical effect such as pyridostigmine ( χ 2 = 0.411, P = 0.395), corticosteroids ( χ 2 = 0.156, P = 0.513), immunoglobulin ( χ 2 = 0.359, P = 0.462), immunosuppressants ( χ 2 = 0.081, P = 0.526) and thymectomy ( χ 2 = 0.337, P = 0.391) between 2 groups were not statistically significant. The ratio of OMG progressing to GMG ( χ 2 = 1.826, P = 0.148), time of progressing (Fisher's exact test: P = 0.639), first onset symptom (Fisher's exact test: P = 0.196) and recurrence time (Fisher's exact test: P = 1.000) were not significantly different between 2 groups. Conclusions AIDMG was more common in female patients. Bilateral ptosis involvement at the same time was more common in AIDMG. Relapse rate during the first 2 years after MG onset was higher in AIDMG than that in NAIDMG. doi: 10.3969/j.issn.1672-6731.2014.10.009

144 patients with various dyshaemopoietic disorders were tested for red blood cell acetylcholinesterase (RBC‐AChE) activity and for in vitro lysis in the acidified‐serum test and sucrose haemolysis test. The RBC‐AChE activity was significantly reduced in acute leukaemia, chronic myeloid leukaemia and myelofibrosis. In all other cases the enzyme activity was normal, except in patients with chronic lymphatic leukaemia complicated with autoimmune haemolytic anaemia. The acidified‐serum test was negative in all cases. The sucrose haemolysis test was positive in a significant number of patients, particularly in those with acute leukaemia, chronic myeloid leukaemia and myelofibrosis.The acute leukaemia and myelofibrosis cases with severe anaemia had lower RBC‐AChE activity than those without or with mild anaemia; also cases with positive sucrose lysis test had lower AChE activity than those with negative test.