Large genotype-phenotype study in carriers of D4Z4 borderline alleles provides guidance for facioscapulohumeral muscular dystrophy diagnosis.

Facioscapulohumeral muscular dystrophy (FSHD) is a myopathy with prevalence of 1 in 20,000. Almost all patients affected by FSHD carry deletions of an integral number of tandem 3.3 kilobase repeats, termed D4Z4, located on chromosome 4q35. Assessment of size of D4Z4 alleles is commonly used for FSHD diagnosis. However, the extended molecular testing has expanded the spectrum of clinical phenotypes. In particular, D4Z4 alleles with 9-10 repeat have been found in healthy individuals, in subjects with FSHD or affected by other myopathies. These findings weakened the strict relationship between observed phenotypes and their underlying genotypes, complicating the interpretation of molecular findings for diagnosis and genetic counseling. In light of the wide clinical variability detected in carriers of D4Z4 alleles with 9-10 repeats, we applied a standardized methodology, the Comprehensive Clinical Evaluation Form (CCEF), to describe and characterize the phenotype of 244 individuals carrying D4Z4 alleles with 9-10 repeats (134 index cases and 110 relatives). The study shows that 54.5% of index cases display a classical FSHD phenotype with typical facial and scapular muscle weakness, whereas 20.1% present incomplete phenotype with facial weakness or scapular girdle weakness, 6.7% display minor signs such as winged scapula or hyperCKemia, without functional motor impairment, and 18.7% of index cases show more complex phenotypes with atypical clinical features. Family studies revealed that 70.9% of relatives carrying 9-10 D4Z4 reduced alleles has no motor impairment, whereas a few relatives (10.0%) display a classical FSHD phenotype. Importantly all relatives of index cases with no FSHD phenotype were healthy carriers. These data establish the low penetrance of D4Z4 alleles with 9-10 repeats. We recommend the use of CCEF for the standardized clinical assessment integrated by family studies and further molecular investigation for appropriate diagnosis and genetic counseling. Especially in presence of atypical phenotypes and/or sporadic cases with all healthy relatives is not possible to perform conclusive diagnosis of FSHD, but all these cases need further studies for a proper diagnosis, to search novel causative genetic defects or investigate environmental factors or co-morbidities that may trigger the pathogenic process. These evidences are also fundamental for the stratification of patients eligible for clinical trials. Our work reinforces the value of large genotype-phenotype studies to define criteria for clinical practice and genetic counseling in rare diseases.

Nusinersen safety and effects on motor function in adult spinal muscular atrophy type 2 and 3.

OBJECTIVE: To retrospectively investigate safety and efficacy of nusinersen in a large cohort of adult Italian patients with spinal muscular atrophy (SMA). METHODS: Inclusion criteria were: (1) clinical and molecular diagnosis of SMA2 or SMA3; (2) nusinersen treatment started in adult age (>18 years); (3) clinical data available at least at baseline (T0-beginning of treatment) and 6 months (T6). RESULTS: We included 116 patients (13 SMA2 and 103 SMA3) with median age at first administration of 34 years (range 18-72). The Hammersmith Functional Rating Scale Expanded (HFMSE) in patients with SMA3 increased significantly from baseline to T6 (median change +1 point, p<0.0001), T10 (+2, p<0.0001) and T14 (+3, p<0.0001). HFMSE changes were independently significant in SMA3 sitter and walker subgroups. The Revised Upper Limb Module (RULM) in SMA3 significantly improved between T0 and T14 (median +0.5, p=0.012), with most of the benefit observed in sitters (+2, p=0.018). Conversely, patients with SMA2 had no significant changes of median HFMSE and RULM between T0 and the following time points, although a trend for improvement of RULM was observed in those with some residual baseline function. The rate of patients showing clinically meaningful improvements (as defined during clinical trials) increased from 53% to 69% from T6 to T14. CONCLUSIONS: Our data provide further evidence of nusinersen safety and efficacy in adult SMA2 and SMA3, with the latter appearing to be cumulative over time. In patients with extremely advanced disease, effects on residual motor function are less clear.

Interpretation of the Epigenetic Signature of Facioscapulohumeral Muscular Dystrophy in Light of Genotype-Phenotype Studies.

Facioscapulohumeral muscular dystrophy (FSHD) is characterized by incomplete penetrance and intra-familial clinical variability. The disease has been associated with the genetic and epigenetic features of the D4Z4 repetitive elements at 4q35. Recently, D4Z4 hypomethylation has been proposed as a reliable marker in the FSHD diagnosis. We exploited the Italian Registry for FSHD, in which FSHD families are classified using the Clinical Comprehensive Evaluation Form (CCEF). A total of 122 index cases showing a classical FSHD phenotype (CCEF, category A) and 110 relatives were selected to test with the receiver operating characteristic (ROC) curve, the diagnostic and predictive value of D4Z4 methylation. Moreover, we performed DNA methylation analysis in selected large families with reduced penetrance characterized by the co-presence of subjects carriers of one D4Z4 reduced allele with no signs of disease or presenting the classic FSHD clinical phenotype. We observed a wide variability in the D4Z4 methylation levels among index cases revealing no association with clinical manifestation or disease severity. By extending the analysis to family members, we revealed the low predictive value of D4Z4 methylation in detecting the affected condition. In view of the variability in D4Z4 methylation profiles observed in our large cohort, we conclude that D4Z4 methylation does not mirror the clinical expression of FSHD. We recommend that measurement of this epigenetic mark must be interpreted with caution in clinical practice.

Assessing the Role of Anti rh-GAA in Modulating Response to ERT in a Late-Onset Pompe Disease Cohort from the Italian GSDII Study Group.

INTRODUCTION: Patients with late-onset Pompe disease (LOPD) receiving enzyme replacement therapy (ERT) may develop IgG antibodies against alglucosidase alpha (anti-rhGAA) in the first 3 months of treatment. The exact role of these antibodies in modulating efficacy of ERT in this group of patients is still not fully understood. To assess whether anti rh-GAA antibodies interfere with ERT efficacy, we studied a large Italian cohort of LOPD patients. METHODS: We analyzed clinical findings and performed serial measurements of IgG anti rh-GAA antibody titers from 64 LOPD patients treated with ERT. The first examination (T0) was completed on average at 17.56 months after starting ERT, while the follow-up (T1) was collected on average at 38.5 months. Differences in T0-T1 delta of the six-minute walking test (6MWT), MRC sum score (MRC), gait, stairs and chair performance (GSGC) and forced vital capacity (FVC) were considered and then related to the antibody titers. RESULTS: Almost 22% of the patients never developed antibodies against GAA, while 78.1% had a positive titer (31.2% patients developed a low titer, 43.8% a medium titer and 3.1% a high titer). No statistical significance was found in relating the T0-T1 delta differences and antibody titers, except for MRC sum score values in a subgroup of patients treated < 36 months, in which those with a null antibody titer showed a greater clinical improvement than patients with a positive titer. CONCLUSION: Our results confirm that in a large cohort of LOPD patients, anti rh-GAA antibody generation did not significantly affect either clinical outcome or ERT efficacy. However, in the first 36 months of treatment, a possible interference of low-medium antibody titers with the clinical status could be present. Therefore, a careful and regular evaluation of antibody titers, especially in cases with evidence of clinical decline despite ERT, should be performed.

Late-onset polyglucosan body myopathy in five patients with a homozygous mutation in GYG1.

Five Sardinian patients presented in their 5th or 6th decade with progressive limb girdle muscle weakness but their muscle biopsies showed vacuolar myopathy. The more or less abundant subsarcolemmal and intermyofibrillar vacuoles showed intense, partially α-amylase resistant, PAS-positive deposits consistent with polyglucosan. The recent description of late-onset polyglucosan myopathy has prompted us to find new genetic defects in the gene (GYG1) encoding glycogenin-1, the crucial primer enzyme of glycogen synthesis in muscle. We found a single homozygous intronic mutation harbored by five patients, who, except for two siblings, appear to be unrelated but all five live in central or south Sardinian villages.

Influence of treatments in multiple sclerosis disability: a cohort study.

BACKGROUND AND OBJECTIVE: A critical aspect of multiple sclerosis (MS) treatments is understanding the effect of disease-modifying drugs (DMDs) on the long-term risk of disability and whether the effect is related to disability at start of treatment. METHODS: We performed an observational study on 3060 MS patients. The effect of therapy on progression to Expanded Disability Status Scale (EDSS) 3.0 and 6.0 from onset was analysed in treated vs untreated (UTP) patients using Cox regression analysis adjusted for propensity score and immortal time bias. RESULTS: Compared to UTP, the risks of EDSS 3.0 were 94% and 73% lower in immunomodulant (IMTP-) and immunosuppressant (ISTP-) treated patients, respectively, while the risk of EDSS 6.0 was 86% lower in IMTP. The risk of EDSS 6.0 was, respectively, 91% and 75% lower in 1275 IMTP before and 114 after EDSS 3.0 than in 539 UTP; the risk was higher in IMTP starting therapy after EDSS 3.0 than before (HR = 4.42). CONCLUSIONS: DMDs delayed long-term disability in MS patients treated either in the early or, to a lesser extent, in the later phase of the disease. Thus, the window of therapeutic opportunity is relatively extended, assuming that early is better than late treatment, but late is better than never.

Overlapping syndromes in laminopathies: a meta-analysis of the reported literature.

Mutations on the LMNA gene are responsible for an heterogeneous group of diseases. Overlapping syndromes related to LMNA gene alterations have been extensively reported. Study scope is to perform a systematic analysis of the overlapping syndromes so far described and to try to correlate the clinical features to the associated genetic alterations. We evaluated all the dominant overlapping syndromes reported by means of a PubMed search and by the analysis of the main databases containing the pathogenic LMNA gene variations and the associated diseases. Metabolic alterations in association to skeletal and/or cardiac alterations proved to be the most frequent overlap syndrome. Overlapping syndromes are mostly associated to inframe mutations in exons 1, 2, 8 and 9. These data further improve the understanding of the pathogenesis of laminopathies.

Cardiac involvement in patients with lamin A/C gene mutations: a cohort observation.

INTRODUCTION: LMNA gene mutations are associated with cardiac and skeletal muscle alterations. METHODS: A cohort of 21 mutated individuals was assessed with clinical and instrumental investigations over the years. RESULTS: The median observation period was 6 years. Cardiac compromise was detected in 16 patients. Bradyarrhythmias were the most frequent manifestations, followed by supraventricular arrhythmias. Two individuals suffered from nonsustained and 1 from sustained ventricular tachyarrhythmias. Dilated cardiomyopathy was detected in 3 patients. Evaluation of the frequencies of the clinical expressions showed a high probability of suffering from analogue heart compromise in study subjects bearing the same LMNA gene mutation. CONCLUSIONS: Cardiac involvement represents a very common phenotypic expression of LMNA gene mutation. Subjects sharing common genetic background seem to suffer from analogue pattern of cardiac manifestation.

Cardiac and muscle imaging findings in a family with X-linked Emery-Dreifuss muscular dystrophy.

The following is a report on a large family with 5 males affected by the X-linked recessive form of Emery-Dreifuss muscular dystrophy with mutation in the STA gene. A detailed longitudinal cardiological evaluation and muscle imaging studies allowed for the assessment of intrafamilial variability of cardiac and muscle involvement. Long term cardiological follow up in the 5 affected males and in 7 female carriers revealed different degrees of severity, ranging from tachycardia-bradycardia syndrome and variable biatrial and left ventricle dilatation, to an episode of isolated symptomatic sustained ventricular tachycardia requiring a device implantation. Muscle imaging in the affected males showed involvement of the soleus and medial head of gastrocnemius on leg muscles and variable involvement on thigh muscles that have not been previously reported. In some cases, imaging showed clear signs of muscle involvement even when no overt signs of weakness could be detected during clinical examination.

Dilated cardiomyopathy with conduction defects in a patient with partial merosin deficiency due to mutations in the laminin-α2-chain gene: a chance association or a novel phenotype?

Patients with a partial reduction of merosin due to mutations in the laminin-α2 chain gene usually present with a mild form of congenital muscular dystrophy or a limb-girdle-like muscular dystrophy. To our knowledge, cardiac impairment has never been reported in such patients. A longitudinal study of a patient with partial laminin-α2 deficiency secondary to mutations in the LAMA2 gene revealed dilated cardiomyopathy with ventricular arrhythmias. Is this a chance association or a novel phenotype?

Aberrant splicing in the LMNA gene caused by a novel mutation on the polypyrimidine tract of intron 5.

INTRODUCTION: Familial dilated cardiomyopathy with conduction system defects variably associated with skeletal muscle abnormalities is frequently caused by LMNA gene mutations. METHODS: A family affected by cardiac abnormalities, either isolated or variably associated with skeletal muscle compromise, was identified. LMNA gene analysis was applied to all family members. RESULTS: A novel intron 5 (c.937-11 C > G) mutation was identified. mRNA transcription analysis was subsequently performed, and cDNA was obtained from mutated patients. It displayed an aberrant splice product featuring the insertion of 40 nucleotides from intron 5, leading to a frameshift. Computational predictions identified a cryptic splice site 40 bp upstream from the canonical site; this alternative splicing event was elicited by intronic mutation, which seems to interfere with the polypyrimidine tract of the canonical site. CONCLUSIONS: We have described the first mutation on the LMNA gene interfering with the polypyrimidine tract. Our findings underline the importance of including introns in the search for mutations.

Muscle imaging analogies in a cohort of patients with different clinical phenotypes caused by LMNA gene mutations.

Laminopathies are a heterogeneous group of LMNA-gene-mutation-related clinical disorders associated with alterations of cardiac and skeletal muscle and peripheral nerves, metabolic defects, and premature aging. Leg muscle imaging investigations were performed in a cohort of patients with LMNA gene alterations who were suffering from Emery-Dreifuss muscular dystrophy, limb-girdle muscular dystrophy type 1B, isolated cardiac disorders or a phenotype of cardiac disorders, and lipodystrophy, including one individual with peripheral neuropathy. Leg muscle imaging revealed varying degrees of alteration in the soleus and medial head of gastrocnemius in each subject. This study demonstrates that LMNA-gene-mutated patients devoid of any clinically detectable skeletal muscle involvement have the same pattern of leg muscle involvement as patients with overt skeletal muscle compromise. This finding suggests the presence of a continuum of skeletal muscle involvement among phenotypes of LMNA-gene-mutation-related skeletalmyopathy and cardiomyopathy.