Lucia Ruggiero

Centronuclear myopathy related to dynamin 2 mutations: Clinical, morphological, muscle imaging and genetic features of an Italian cohort

Mutations in dynamin 2 (DNM2) gene cause autosomal dominant centronuclear myopathy and occur in around 50% of patients with centronuclear myopathy. We report clinical, morphological, muscle imaging and genetic data of 10 unrelated Italian patients with centronuclear myopathy related to DNM2 mutations. Our results confirm the clinical heterogeneity of this disease, underlining some peculiar clinical features, such as severe pulmonary impairment and jaw contracture that should be considered in the clinical follow-up of these patients. Muscle MRI showed a distinct pattern of involvement, with predominant involvement of soleus and tibialis anterior in the lower leg muscles, followed by hamstring muscles and adductor magnus at thigh level and gluteus maximus. The detection of three novel DNM2 mutations and the first case of somatic mosaicism further expand the genetic spectrum of the disease.

Large scale genotype-phenotype analyses indicate that novel prognostic tools are required for families with facioscapulohumeral muscular dystrophy.

Facioscapulohumeral muscular dystrophy has been genetically linked to reduced numbers (≤8) of D4Z4 repeats at 4q35 combined with 4A(159/161/168) DUX4 polyadenylation signal haplotype. However, we have recently reported that 1.3% of healthy individuals carry this molecular signature and 19% of subjects affected by facioscapulohumeral muscular dystrophy do not carry alleles with eight or fewer D4Z4 repeats. Therefore, prognosis for subjects carrying or at risk of carrying D4Z4 reduced alleles has become more complicated. To test for additional prognostic factors, we measured the degree of motor impairment in a large group of patients affected by facioscapulohumeral muscular dystrophy and their relatives who are carrying D4Z4 reduced alleles. The clinical expression of motor impairment was assessed in 530 subjects, 163 probands and 367 relatives, from 176 unrelated families according to a standardized clinical score. The associations between clinical severity and size of D4Z4 allele, degree of kinship, gender, age and 4q haplotype were evaluated. Overall, 32.2% of relatives did not display any muscle functional impairment. This phenotype was influenced by the degree of relation with proband, because 47.1% of second- through fifth-degree relatives were unaffected, whereas only 27.5% of first-degree family members did not show motor impairment. The estimated risk of developing motor impairment by age 50 for relatives carrying a D4Z4 reduced allele with 1–3 repeats or 4–8 repeats was 88.7% and 55%, respectively. Male relatives had a mean score significantly higher than females (5.4 versus 4.0, P = 0.003). No 4q haplotype was exclusively associated with the presence of disease. In 13% of families in which D4Z4 alleles with 4–8 repeats segregate, the diagnosis of facioscapulohumeral muscular dystrophy was reported only in one generation. In conclusion, this large-scale analysis provides further information that should be taken into account when counselling families in which a reduced allele with 4–8 D4Z4 repeats segregates. In addition, the reduced expression of disease observed in distant relatives suggests that a family’s genetic background plays a role in the occurrence of facioscapulohumeral muscular dystrophy. These results indicate that the identification of new susceptibility factors for this disease will require an accurate classification of families.

TM6SF2 Glu167Lys polymorphism is associated with low levels of LDL-cholesterol and increased liver injury in obese children.

The Glu167Lys (E167K) transmembrane 6 superfamily member 2 (TM6SF2) variant has been associated with liver steatosis, high alanine transaminase (ALT) levels and reduced plasma levels of liver‐derived triglyceride‐rich lipoproteins.

Next generation sequencing on patients with LGMD and nonspecific myopathies: Findings associated with ANO5 mutations

Highlights • We have carried out the largest screening of the ANO5 gene.• We identified 33 patients (4%) with pathogenic changes in both alleles and 23 heterozygotes (3%).• The identification of a ANO5 carrier is not to be considered an uncommon finding.• The anoctaminopathies have an extremely high genetic and phenotypic heterogeneity.• NGS-based strategies are perfect to dissect the clinical variability in NMDs.

The genetic basis of undiagnosed muscular dystrophies and myopathies Results from 504 patients

Objective: To apply next-generation sequencing (NGS) for the investigation of the genetic basis of undiagnosed muscular dystrophies and myopathies in a very large cohort of patients. Methods: We applied an NGS-based platform named MotorPlex to our diagnostic workflow to test muscle disease genes with a high sensitivity and specificity for small DNA variants. We analyzed 504 undiagnosed patients mostly referred as being affected by limb-girdle muscular dystrophy or congenital myopathy. Results: MotorPlex provided a complete molecular diagnosis in 218 cases (43.3%). A further 160 patients (31.7%) showed as yet unproven candidate variants. Pathogenic variants were found in 47 of 93 genes, and in more than 30% of cases, the phenotype was nonconventional, broadening the spectrum of disease presentation in at least 10 genes. Conclusions: Our large DNA study of patients with undiagnosed myopathy is an example of the ongoing revolution in molecular diagnostics, highlighting the advantages in using NGS as a first-tier approach for heterogeneous genetic conditions.

Clinical expression of facioscapulohumeral muscular dystrophy in carriers of 1-3 D4Z4 reduced alleles: Experience of the FSHD Italian National Registry

Objectives Facioscapulohumeral muscular dystrophy type 1 (FSHD1) has been genetically linked to reduced numbers (≤8) of D4Z4 repeats at 4q35. Particularly severe FSHD cases, characterised by an infantile onset and presence of additional extra-muscular features, have been associated with the shortest D4Z4 reduced alleles with 1–3 repeats (1–3 DRA). We searched for signs of perinatal onset and evaluated disease outcome through the systematic collection of clinical and anamnestic records of de novo and familial index cases and their relatives, carrying 1–3 DRA. Setting Italy. Participants 66 index cases and 33 relatives carrying 1–3 DRA. Outcomes The clinical examination was performed using the standardised FSHD evaluation form with validated inter-rater reliability. To investigate the earliest signs of disease, we designed the Infantile Anamnestic Questionnaire (IAQ). Comparison of age at onset was performed using the non-parametric Wilcoxon rank-sum or Kruskal-Wallis test. Comparison of the FSHD score was performed using a general linear model and Wald test. Kaplan-Meier survival analysis was used to estimate the age-specific cumulative motor impairment risk. Results No patients had perinatal onset. Among index cases, 36 (54.5%) showed the first signs by 10 years of age. The large majority of patients with early disease onset (26 out of 36, 72.2%) were de novo; whereas the majority of patients with disease onset after 10 years of age were familial (16, 53.3%). Comparison of the disease severity outcome between index cases with age at onset before and over 10 years of age, failed to detect statistical significance (Wald test p value=0.064). Of 61 index cases, only 17 (27.9%) presented extra-muscular conditions. Relatives carrying 1–3 DRA showed a large clinical variability ranging from healthy subjects, to patients with severe motor impairment. Conclusions The size of the D4Z4 allele is not always predictive of severe clinical outcome. The high degree of clinical variability suggests that additional factors contribute to the phenotype complexity.

Aminotransferases and muscular diseases: A disregarded lesson. Case reports and review of the literature

The aim of this study was to call the attention to the often disregarded message that hypertransaminasemia may be a marker of both liver and muscle diseases by presenting personal case reports and a systematic literature review. Three male children (mean age 5.7 years) were inappropriately addressed, during the last 12 months, to our paediatric liver unit for diagnostic work‐up of a chronic hypertransaminasemia of unknown origin. In one of them, a liver biopsy had already been performed. On admission, physical examination, evaluation of serum levels of creatine kinase, and dystrophin genetic testing finally led to a diagnosis of muscular dystrophy. One hundred fourteen similar cases, 21 with unnecessary liver biopsy, were found by Medline search. Expensive and invasive tests planned to investigate liver diseases should be postponed until alternative sources of increased serum aminotransferases, primarily myopathic injury, have been excluded.

Electrophysiological characterisation in hereditary spastic paraplegia type 5

OBJECTIVE To assess in SPG5 hereditary spastic paraparesis (HSP) the involvement of the central (CNS) and the peripheral (PNS) nervous system by a multimodal electrophysiological approach. METHODS Four patients belonging to three HSP families, with a molecular diagnosis of SPG5, underwent electrophysiological evaluation including electromyography (EMG) and nerve conduction study (NCS), motor-evoked potentials (MEPs) by transcranial magnetic stimulation (TMS) and somatosensory evoked potentials (SEPs) at upper and lower limbs, visual (VEPs) and brainstem auditory evoked potentials (BAEPs). In one patient, electrophysiological evaluation was performed twice at the age of 12 and 31 years. RESULTS EMG and NCS were normal. MEPs and SEPs were abnormal in all patients along the central pathway for upper and/or lower limbs. VEPs revealed a damage of visual pathway and BAEPs showed the involvement of auditory pathway within the brainstem. In the patient who underwent electrophysiological follow-up, MEP and SEP findings were unmodified, whereas VEPs showed no reproducible responses. CONCLUSIONS We report an extensive electrophysiological evaluation of SPG5 and we confirm that the SPG5 phenotype may be broader than pure presentation. SIGNIFICANCE Electrophysiological evaluation, showing diffuse CNS involvement with PNS sparing, could be very useful to address the molecular diagnosis and to follow-up a hypothetical treatment.

Central cholinergic dysfunction in the adult form of Niemann Pick disease type C: a further link with Alzheimer’s disease?

Adult patients with Niemann-Pick disease type C (NPC) usually develop cognitive impairment progressing to dementia, whose pathophysiology remains still unclear. Noteworthy parallels exist in cognitive impairment and cellular pathology of NPC and Alzheimer’s disease (AD). In particular, alterations of cholinergic system, which represent one of the pathological hallmarks and contribute to cognitive deterioration in AD, have recently been demonstrated in a human brain autopsy and in an experimental model of NPC. This finding raised the issue that central cholinergic circuits dysfunction may contribute to pathophysiology of cognitive impairment in NPC as well, and prompted us to evaluate the cholinergic functional involvement in NPC patients by applying a neurophysiologic technique, named short-latency afferent inhibition (SAI). We describe clinical, biochemical, molecular and neuropsychological features, and SAI findings in three patients affected by NPC. Diagnosis of NPC was assessed by molecular analysis of the NPC1 gene in all patients. In two of them, biochemical analysis of intracellular accumulation of unesterified cholesterol was also performed. The main clinical features were cerebellar ataxia, vertical supranuclear gaze palsy and a variable degree of cognitive impairment ranging from only memory impairment to severe dementia. Electrophysiological evaluation revealed a reduced SAI in all three patients. Our SAI findings provide evidence of cholinergic dysfunction in patients with the adult form of NPC, supporting that cholinergic alterations may play a role in cognitive impairment in NPC, and strengthening the similarities between NPC and AD.

MYH7-related myopathies: clinical, histopathological and imaging findings in a cohort of Italian patients.

BackgroundMyosin heavy chain 7 (MYH7)-related myopathies are emerging as an important group of muscle diseases of childhood and adulthood, with variable clinical and histopathological expression depending on the type and location of the mutation. Mutations in the head and neck domains are a well-established cause of hypertrophic cardiomyopathy whereas mutation in the distal regions have been associated with a range of skeletal myopathies with or without cardiac involvement, including Laing distal myopathy and Myosin storage myopathy. Recently the spectrum of clinical phenotypes associated with mutations in MYH7 has increased, blurring this scheme and adding further phenotypes to the list. A broader disease spectrum could lead to misdiagnosis of different congenital myopathies, neurogenic atrophy and other neuromuscular conditions.ResultsAs a result of a multicenter Italian study we collected clinical, histopathological and imaging data from a population of 21 cases from 15 families, carrying reported or novel mutations in MYH7. Patients displayed a variable phenotype including atypical pictures, as dropped head and bent spine, which cannot be classified in previously described groups. Half of the patients showed congenital or early infantile weakness with predominant distal weakness. Conversely, patients with later onset present prevalent proximal weakness. Seven patients were also affected by cardiomyopathy mostly in the form of non-compacted left ventricle. Muscle biopsy was consistent with minicores myopathy in numerous cases. Muscle MRI was meaningful in delineating a shared pattern of selective involvement of tibialis anterior muscles, with relative sparing of quadriceps.ConclusionThis work adds to the genotype-phenotype correlation of MYH7-relatedmyopathies confirming the complexity of the disorder.