Ivana Basta

A comprehensive analysis of the epidemiology and clinical characteristics of anti-LRP4 in myasthenia gravis.

Double-seronegative myasthenia gravis (dSN-MG, without detectable AChR and MuSK antibodies) presents a serious gap in MG diagnosis and understanding. Recently, autoantibodies against the low-density lipoprotein receptor-related protein 4 (LRP4) have been identified in several dSN-MG sera, but with dramatic frequency variation (∼2-50%). We have developed a cell based assay (CBA) based on human LRP4 expressing HEK293 cells, for the reliable and efficient detection of LRP4 antibodies. We have screened about 800 MG patient sera from 10 countries for LRP4 antibodies. The overall frequency of LRP4-MG in the dSN-MG group (635 patients) was 18.7% but with variations among different populations (range 7-32.7%). Interestingly, we also identified double positive sera: 8/107 anti-AChR positive and 10/67 anti-MuSK positive sera also had detectable LRP4 antibodies, predominantly originating from only two of the participating groups. No LRP4 antibodies were identified in sera from 56 healthy controls tested, while 4/110 from patients with other neuroimmune diseases were positive. The clinical data, when available, for the LRP4-MG patients were then studied. At disease onset symptoms were mild (81% had MGFA grade I or II), with some identified thymic changes (32% hyperplasia, none with thymoma). On the other hand, double positive patients (AChR/LRP4-MG and MuSK/LRP4-MG) had more severe symptoms at onset compared with any single positive MG subgroup. Contrary to MuSK-MG, 27% of ocular dSN-MG patients were LRP4 antibody positive. Similarly, contrary to MuSK antibodies, which are predominantly of the IgG4 subtype, LRP4 antibodies were predominantly of the IgG1 and IgG2 subtypes. The prevalence was higher in women than in men (female/male ratio 2.5/1), with an average disease onset at ages 33.4 for females and 41.9 for males. Overall, the response of LRP4-MG patients to treatment was similar to published responses of AChR-MG rather than to MuSK-MG patients.

Cyclosporine in the treatment of myasthenia gravis

Cyclosporine A (CsA) treatment was evaluated in 52 patients with severe generalized myasthenia gravis (MG) whose illness was not controlled by anticholinesterase drugs, thymectomy, corticosteroids, and azathioprine. The efficacy of CsA treatment was expressed by mean disability score quotient (MDSQ), which was obtained by comparing mean disability score (MDS) at the beginning of the treatment with the MDS at the end of the follow‐up period. For the entire group of patients MDSQ was 53.3%, indicating moderate improvement. Analyzing individual cases, eight patients (15%) did not improve, 17 (33%) showed moderate improvement, 20 (38%) showed remarkable improvement, and seven patients (14%) achieved complete remission. The most common side effects were rise of serum creatinine (seven), hypertension (two), gingival hyperplasia (two), hypertrichosis (six), myalgia (10), and ‘flu‐like’ symptoms (10 patients). The results of this study suggest that CsA is efficacious and safe treatment in severe and resistant forms of MG.

Influence of multisystemic affection on health-related quality of life in patients with myotonic dystrophy type 1.

AIM To assess health-related quality of life (HRQoL) in patients with DM1, to identify muscular, multisystemic, central and social factors that may affect QoL and to define a DM1 patient in risk of poor QoL. PATIENTS AND METHOD This cross-sectional study comprised 120 DM1 consecutive patients. The following scales were used: Multidimensional Scale of Perceived Social Support (MSPSS), Muscular Impairment Rating Scale (MIRS), battery of neuropsychological tests, acceptance of illness scale (AIS), Hamilton rating scale for depression (Ham-D), Krupps Fatigue Severity Scale (FSS), Daytime Sleepiness Scale (DSS) and SF-36 questionnaire. RESULTS HRQoL was impaired in DM1 patients in both physical and mental domains (PCS was 41.8±23.5, MCS 47.0±24.3 and total SF-36 score 45.6±24.0). The most significant factors correlating with better SF-36 total score were younger age (β=-0.45, p<0.001), shorter duration of disease (β=-0.27, p=0.001), higher education (β=0.20, p=0.009), less severe muscular weakness (β=-0.52, p<0.001), normal swallowing (β=0.22, p=0.005), absence of fainting (β=0.31, p=0.002), absence of snoring (β=0.21, p=0.036), better acceptance of disease (β=-0.17, p=0.036), lower depressiveness (β=-0.46, p=0.001), lower fatigue (β=-0.32, p=0.001), absence of cataract (β=-0.21, p=0.034), absence of kyphosis (β=0.31, p=0.004) and absence of constipation (β=0.24, p=0.016). Second linear regression analysis revealed that depressed (β=-0.38, p<0.001) and elder patients (β=-0.27, p=0.007) and as well as those with poor acceptance of illness (β=-0.21, p=0.006) were in especially higher risk of having poor HRQoL (R(2)=0.68). CONCLUSION We identified different central, social, muscular, cardiorespiratory and other factors correlating with HRQoL. It is of great importance that most of these factors are amenable to treatment.

Significant impact of behavioral and cognitive impairment on quality of life in patients with myotonic dystrophy type 1.

OBJECTIVE To assess an impact of cognitive and behavioral impairment on QoL in a larger cohort of patients with DM1. METHODS Sixty six genetically confirmed DM1 patients (22 with juvenile (jDM1) and 44 with adult form (aDM1) of the disease) were recruited. Following behavioral tests were used: Hamilton scales for depression and anxiety (HamD and HamA), Daytime Sleepiness Scale (DSS), and Krupps Fatigue Severity Scale (FSS). Patients also underwent detailed classic neuropsychological investigation and Cambridge Neuropsychological Test Automated Battery (CANTAB). Individualized Neuromuscular Quality of Life questionnaire (INQoL) was used as a measure of QoL. RESULTS Patients with jDM1 scored lower than aDM1 patients regarding total INQoL score and all INQoL subdomains, except for myotonia. Significant predictors of total INQoL score in patients with jDM1 were severity of fatigue (β=+0.60, p<0.01) and percentage of correct responses on Spatial Recognition Memory test from CANTAB that measures visuospatial abilities (β=-0.38, p<0.05). The most important predictors of total INQoL score in patients with aDM1 were severity of fatigue (β=+0.36, p<0.05) and level of education (β=-0.29, p<0.05). CONCLUSION Our results showed clear influence of different central manifestations on QoL in patients with both aDM1 and jDM1.

Titin antibodies in “seronegative” myasthenia gravis — A new role for an old antigen

Myasthenia gravis (MG) is an autoimmune disease caused by antibodies targeting the neuromuscular junction of skeletal muscles. Triple-seronegative MG (tSN-MG, without detectable AChR, MuSK and LRP4 antibodies), which accounts for ~10% of MG patients, presents a serious gap in MG diagnosis and complicates differential diagnosis of similar disorders. Several AChR antibody positive patients (AChR-MG) also have antibodies against titin, usually detected by ELISA. We have developed a very sensitive radioimmunoprecipitation assay (RIPA) for titin antibodies, by which many previously negative samples were found positive, including several from tSN-MG patients. The validity of the RIPA results was confirmed by western blots. Using this RIPA we screened 667 MG sera from 13 countries; as expected, AChR-MG patients had the highest frequency of titin antibodies (40.9%), while MuSK-MG and LRP4-MG patients were positive in 14.6% and 16.4% respectively. Most importantly, 13.4% (50/372) of the tSN-MG patients were also titin antibody positive. None of the 121 healthy controls or the 90 myopathy patients, and only 3.6% (7/193) of other neurological disease patients were positive. We thus propose that the present titin antibody RIPA is a useful tool for serological MG diagnosis of tSN patients.

Peripheral neuropathy in patients with myotonic dystrophy type 1

Abstract Objectives: To assess the frequency and type of peripheral neuropathy (PNP) in patients with myotonic dystrophy type 1 (DM1), as well as to identify factors that may be associated with this abnormality. Methods: This study comprised 111 adult patients with DM1. Nerve conduction study was performed on sural, peroneal and median nerves of both limbs. Results: PNP was somewhat more frequent in DM1 patients with glucose intolerance and diabetes mellitus (66·7 vs 33·7%, P = 0·05). In DM1 patients with no glucose intolerance, diabetes mellitus and thyroid dysfunction, the most frequent type of PNP was demyelinating (70·0%) and motor (83·3%). PNP was more frequent in males (45·7 vs 20·9%, P<0·05). Patients with PNP were older (43·7±7·3 vs 39·6±9·6 years, P<0·05) and had a longer duration of DM1 compared to those without PNP (18·6±9·9 vs 12·7±8·3 years, P<0·01). DM1 patients with PNP had a higher body mass index) (24·9±5·5 vs 22·4±4·2 kg/cm2, P<0·05), higher triglycerides (3·1±3·3 vs 1·8±0·8 mmol/l, P<0·01), total cholesterol (6·2±1·4 vs 5·4±1·1 mmol/l) and LDL cholesterol (4·3±1·2 vs 3·4±1·0, P<0·05). Achilles reflexes were absent in 76·9% patients with PNP and in 51·9% patients without PNP (P<0·05). Patellar reflexes and muscle strength were similar in both groups (P>0·05). Conclusions: PNP was present in one-third of DM1 patients. The most common type was motor and demyelinating PNP. Our results suggest the association between the presence of peripheral nerve impairment in DM1 and male gender, age, duration of disease and certain metabolic parameters.

Intergenerational changes of CTG repeat depending on the sex of the transmitting parent in myotonic dystrophy type 1.

Sir, Myotonic dystrophy type 1 (DM1) is an autosomal dominant, multisystemic disease caused by expansion of a CTG repeat, located in the 3¢ untranslated region of dystrophia myotonica protein kinase (DMPK) gene in the chromosome region 19q13.3. Normal DMPK alleles contain between five and 37 copies of the CTG repeat, but this number is greatly increased in DM1 patients. DM1 is the locus that appears to show the most dramatic instability, often with very high levels of somatic mosaicism and very large intergenerational differences. To date, most studies have concentrated on the comparison of blood DNA from patients within families, and the parent–child differences observed defined as intergenerational differences (Harley et al., 1992; Ashizawa et al., 1993; O’Hoy et al., 1993; Martorell et al., 2000). Size of CTG repeat expansion usually increases upon intergeneration transmission and underlies the phenomena of genetic anticipation. However, the reduction in size of the DM1 trinucleotide repeat mutation during transmission is relatively rare. The aim of this study was to analyse the role of parents sex in intergenerational changes of CTG repeats in patients with DM1. Fifty-four DM1 patients (31 males and 23 females), aged between 19 and 51 years (mean ± SD: 36 ± 15), were studied. Diagnosis was based on clinical, electromyographic and genetic examination. Genomic DNA was isolated from white blood cells using proteinase K/SDS digestion and phenol-chloroform extraction. All subjects were studied by both polymerase chain reaction (PCR) and southern blot analyses. All samples showed a series of discrete bands representing somatic mosaicism of diseaseassociated alleles seen in the blood of DM1 patients. The size of each discrete band (expanded allele) was determined according to DNA molecular weight marker, using scatter plot on which band size of DNA marker was plotted against the length to which it migrated in the gel. For each patient the progenitor, the average, and the largest allele was estimated from the lower boundary of the series of discrete bands observed in allele distribution in lymphocytes beyond which rare alleles were detected in repeated analyses. PCR, as previously described (Brook et al., 1992), was performed for precise determination of wild type (wt) DMPK alleles size. Products were resolved on 6% denaturing polyacrylamide gels, detected by silver staining, and a number of CTG repeats was determined using a DNA sequencing ladder. Out of 54 investigated DM1 patients, 30 inherited the DM1 mutation from their mothers and 24 from their affected fathers. Analysis of variance showed that the mean of the smallest CTG expansion (progenitor allele) was smaller in patients with paternal DM1 mutation inheritance (194 ± 113 CTG repeats) than in those with maternal inheritance (292 ± 123 CTG repeats), P < 0.05. The same was found when comparing the means of the average expansions. Conversely, there was no significant influence of parents sex on the value of the largest CTG expansion (P > 0.05), Table 1. We analysed intergenerational changes of the smallest CTG repeats (progenitor alleles) in 20 parent– child pairs (16 mother–child and four father–child pairs). All 16 mother–child pairs exhibited increased CTG repeat expansion in the children (from 63 to 159 CTG repeats in the mothers and 129–596 CTG repeats in the children). A 22-yearold woman exhibited typical clinical signs for juvenile-adult type of DM1 and DMPK expansion range in blood cells from 429 to 900 repeats. As she has a risk of having children affected with congenital type of DM1, she was referred for prenatal diagnosis. CVS sample was taken during gestation week 10, and isolated DNA was tested for DM1 mutation using SP/LR PCR. The CVS sample was contaminated with maternal DNA. Repeated prenatal diagnosis from DNA isolated from amniotic fluid cells revealed the presence of expansion in the range of 2000–3000 CTG repeats. This pregnancy was terminated. From four father–child pairs, we found increased CTG repeat expansion in three pairs, but in one paternal transmission we found reduction (contraction) in size of the CTG repeats (from 113 in the father to 96 in the child). This study shows that maternal transmission of the DM1 mutation results in a greater number of CTG repeats than does paternal transmission. This suggests a greater instability of mutant alleles in female meiosis and predominantly

Cardiologic predictors of sudden death in patients with myotonic dystrophy type 1

The aim of this study was to analyze survival, causes of death and cardiologic predictors of sudden death in a large cohort of patients with myotonic dystrophy type 1 (DM1). The study was comprised of 171 adult DM1 patients hospitalized at the Neurology Clinic in a 20-year period. Severe electrocardiographic (ECG) abnormality included at least one of the following: rhythm other than sinus, PR interval of ≥240 ms, QRS complex duration of 120 ms or more, and second-degree or third-degree atrioventricular (AV) block. Survival data were analyzed by the Kaplan-Meier test, log-rank test and Cox regression analysis. During the mean follow-up period of 9.4±5.4 years, a pacemaker was implanted in 5.8% of DM1 patients and 14% of patients died. The mean age at death was 55.6±12.5 years. The most common causes of death in our cohort were sudden death (41.7%) and respiratory failure (29.2%). The presence of palpitations (hazard ratio [HR]=4.7, p<0.05) and increased systolic blood pressure (HR=9.8, p<0.05) were significant predictors of sudden death. Among ECG parameters, severe ECG abnormality (HR=4.7, p<0.05), right bundle branch block (RBBB; HR=3.9, p<0.05) and bifascicular block (HR=5.8, p<0.05) were significant predictors of sudden death.

The predictive value of the presence of different antibodies and thymus pathology to the clinical outcome in patients with generalized myasthenia gravis

OBJECTIVES To analyze the predictive value of anti-acetylcholine receptor antibodies (anti-AChR Ab) and anti-muscle specific kinase antibodies (anti-MuSK Ab), as well as the thymus pathology to the clinical outcome in patients with generalized myasthenia gravis (MG). METHODS We analyzed 138 patients with generalized MG, who were thymectomized and assayed for anti-AChR Ab and anti-MuSK Ab. RESULTS Anti-AChR Ab were detected in 84% of patients, while anti-MuSK Ab were present in 36% of the AChR Ab negative patients. Severe forms of the disease were more frequent in MuSK Ab positive, compared to the AChR Ab positive and complete seronegative patients. Thymic lymphoid follicular hyperplasia (LFH) was present in 60%, thymoma in 23%, atrophic thymus in 9% and the normal thymus in 8% of patients. LFH was more frequent among women, while thymoma and atrophic thymus were more frequent in men. The younger patients mainly had LFH and normal thymus, while thymoma and atrophic thymus were more frequent in older patients. The mildest clinical presentation was present in patients with normal thymus, while severe forms of the disease were registered in the patients with thymoma. The AChR Ab positive patients had more often LFH and thymoma, while within MuSK Ab positive patients atrophic thymus was most common. CONCLUSION The best disease outcome was observed in patients with normal thymus or LFH with anti-AChR Ab or without both types of antibodies.

Transcranial sonography in patients with myotonic dystrophy type 1

Introduction: In this study we analyzed transcranial sonography (TCS) in patients with myotonic dystrophy type 1 (DM1). Methods: This cross‐sectional study included 66 DM1 patients and 55 matched healthy controls (HCs). Echogenicity of the brainstem raphe (BR) and substantia nigra (SN) and third ventricle width (DTV) were assessed by TCS. Results: BR hypoechogenicity was more common in DM1 patients than in HCs (37.7% vs. 7.8%, P < 0.01). Patients with depression or fatigue were more likely to have BR hypoechogenicity (80.0% vs. 29.4%, P < 0.01 and 51.9% vs. 24.2%, P < 0.05, respectively). Both hypoechogenicity and hyperechogenicity of SN were more frequent in DM1 patients than in controls (26.2% vs. 10.9% and 13.1% vs. 1.8%, respectively, P < 0.01). DTV was increased in DM1 patients compared with HCs (6.0 ± 1.4 vs. 4.9 ± 0.9 mm, P < 0.01). Conclusion: TCS can offer new insight into structural changes of several cerebral areas in patients with DM1. Muscle Nerve 50:278–282, 2014