Eugenio Mercuri

Mutations in the fukutin-related protein gene (FKRP) cause a form of congenital muscular dystrophy with secondary laminin alpha2 deficiency and abnormal glycosylation of alpha-dystroglycan.

The congenital muscular dystrophies (CMD) are a heterogeneous group of autosomal recessive disorders presenting in infancy with muscle weakness, contractures, and dystrophic changes on skeletal-muscle biopsy. Structural brain defects, with or without mental retardation, are additional features of several CMD syndromes. Approximately 40% of patients with CMD have a primary deficiency (MDC1A) of the laminin alpha2 chain of merosin (laminin-2) due to mutations in the LAMA2 gene. In addition, a secondary deficiency of laminin alpha2 is apparent in some CMD syndromes, including MDC1B, which is mapped to chromosome 1q42, and both muscle-eye-brain disease (MEB) and Fukuyama CMD (FCMD), two forms with severe brain involvement. The FCMD gene encodes a protein of unknown function, fukutin, though sequence analysis predicts it to be a phosphoryl-ligand transferase. Here we identify the gene for a new member of the fukutin protein family (fukutin related protein [FKRP]), mapping to human chromosome 19q13.3. We report the genomic organization of the FKRP gene and its pattern of tissue expression. Mutations in the FKRP gene have been identified in seven families with CMD characterized by disease onset in the first weeks of life and a severe phenotype with inability to walk, muscle hypertrophy, marked elevation of serum creatine kinase, and normal brain structure and function. Affected individuals had a secondary deficiency of laminin alpha2 expression. In addition, they had both a marked decrease in immunostaining of muscle alpha-dystroglycan and a reduction in its molecular weight on western blot analysis. We suggest these abnormalities of alpha-dystroglycan are caused by its defective glycosylation and are integral to the pathology seen in MDC1C.

Origin and timing of brain lesions in term infants with neonatal encephalopathy

BACKGROUND The role of intrapartum asphyxia in neonatal encephalopathy and seizures in term infants is not clear, and antenatal factors are being implicated in the causal pathway for these disorders. However, there is no evidence that brain damage occurs before birth. We aimed to test the hypothesis that neonatal encephalopathy, early neonatal seizures, or both result from early antenatal insults. METHODS We used brain MRI or post-mortem examination in 351 fullterm infants with neonatal encephalopathy, early seizures, or both to distinguish between lesions acquired antenatally and those that developed in the intrapartum and early post-partum period. We excluded infants with major congenital malformations or obvious chromosomal disorders. Infants were divided into two groups: those with neonatal encephalopathy (with or without seizures), and evidence of perinatal asphyxia (group 1); and those without other evidence of encephalopathy, but who presented with seizures within 3 days of birth (group 2). FINDINGS Brain images showed evidence of an acute insult without established injury or atrophy in 197 (80%) of infants in group 1, MRI showed evidence of established injury in only 2 infants (<1%), although tiny foci of established white matter gliosis, in addition to acute injury, were seen in three of 21 on post-mortem examination. In group 2, acute focal damage was noted in 62 (69%) of infants. Two (3%) also had evidence of antenatal injury. INTERPRETATION Although our results cannot exclude the possibility that antenatal or genetic factors might predispose some infants to perinatal brain injury, our data strongly suggest that events in the immediate perinatal period are most important in neonatal brain injury.

Clinical and molecular genetic spectrum of autosomal dominant Emery‐Dreifuss muscular dystrophy due to mutations of the lamin A/C gene

Emery‐Dreifuss muscular dystrophy (EDMD) is characterized by early contractures of the elbows and Achilles tendons, slowly progressive muscle wasting and weakness, and life‐threatening cardiomyopathy with conduction blocks. We recently identified LMNA encoding two nuclear envelope proteins, lamins A and C, to be implicated in the autosomal dominant form of EDMD. Here, we report on the variability of the phenotype and spectrum of LMNA mutations in 53 autosomal dominant EDMD patients (36 members of 6 families and 17 sporadic cases). Twelve of the 53 patients showed cardiac involvement exclusively, although the remaining 41 all showed muscle weakness and contractures. We were able to identify a common phenotype among the patients with skeletal muscle involvement, consisting of humeroperoneal wasting and weakness, scapular winging, rigidity of the spine, and elbow and Achilles tendon contractures. The disease course was generally slow, but we observed either a milder phenotype characterized by late onset and a mild degree of weakness and contractures or a more severe phenotype with early presentation and a rapidly progressive course in a few cases. Mutation analysis identified 18 mutations in LMNA (ie, 1 nonsense mutation, 2 deletions of a codon, and 15 missense mutations). All the mutations were distributed between exons 1 and 9 in the region of LMNA that is common to lamins A and C. LMNA mutations arose de novo in 76% of the cases; 2 of these de novo mutations were typical hot spots, and 2 others were identified in 2 unrelated cases. There was no clear correlation between the phenotype and type or localization of the mutations within the gene. Moreover, a marked inter‐ and intra‐familial variability in the clinical expression of LMNA mutations exists, ranging from patients expressing the full clinical picture of EDMD to those characterized only by cardiac involvement, which points toward a significant role of possible modifier genes in the course of this disease. In conclusion, the high proportion of de novo mutations together with the large spectrum of both LMNA mutations and the expression of the disease should now prompt screening for LMNA in familial and sporadic cases of both EDMD and dilated cardiomyopathy associated with conduction system disease. Ann Neurol 2000;48:170–180

Early prognostic indicators of outcome in infants with neonatal cerebral infarction : A clinical, electroencephalogram, and magnetic resonance imaging study

Objective. The aim of this study was to identify prognostic factors in newborns with cerebral infarction. Design. Antenatal and perinatal factors and early clinical, electroencephalogram (EEG), and magnetic resonance imaging (MRI) findings were compared with neurodevelopmental outcome in 24 children with evidence of cerebral infarction on neonatal MRI. Results. Out of 24 infants, 19 had an infarction in the territory of a major cerebral vessel and 5 in the borderzone between cerebral arteries. Neuromotor outcome was normal in 17 and abnormal in 7 infants. Of these 7 infants, 5 infants showed a definite hemiplegia, whereas the other 2 showed some asymmetry of tone or function but no definite hemiplegia. None of the adverse antenatal or perinatal factors was significantly associated with abnormal outcome. Neonatal clinical examination was also not always predictive of the outcome. The extent of the lesion on MRI was a better predictor. In particular, it was the concomitant involvement of hemisphere, internal capsule and basal ganglia that was always associated with an abnormal outcome whereas the involvement of only one or two of the three tended to be associated with a normal outcome. EEG was also very helpful. Abnormal background activity either unilateral or bilateral was found in 6 infants and 5 out of 6 developed hemiplegia. In contrast, the presence of seizure activity in presence of a normal background was not related to abnormal outcome. Conclusions. Early MRI and EEG can help to identify the infants with cerebral infarction who are likely to develop hemiplegia.

Muscle MRI in inherited neuromuscular disorders: past, present, and future.

Interest in muscle MRI has been largely stimulated in the last few years by the recognition of an increasing number of genetic defects in the field of inherited neuromuscular disorders. Muscle ultrasound (US) and computed tomography (CT) have been used to detect the presence of muscle involvement in patients affected by these disorders, but until recently the use of muscle MRI has been, with a few exceptions, limited to detecting inflammatory forms. The aim of this review is to illustrate how muscle MRI, in combination with clinical evaluation, can contribute to the selection of appropriate genetic tests and more generally in the differential diagnosis of genetically distinct forms of neuromuscular disorders. Possible future applications of muscle MRI are also discussed. J. Magn. Reson. Imaging 2007.

Phenotypic spectrum associated with mutations in the fukutin-related protein gene

We describe 22 patients with mutations in the fukutin‐related protein (FKPR) gene. Four patients had congenital muscular dystrophy (MDC1C), with presentation at birth, severe weakness and inability to stand unsupported. The other 18 had limb girdle muscular dystrophy (LGMD2I). Eleven showed a Duchenne‐like course with loss of ambulation in the early teens while 7 had a milder phenotype. Muscle biopsy invariably showed abnormal expression of a‐dystroglycan. MDC1C patients either carried 2 missense or 1 missense and 1 nonsense mutations. Patients with LGMD2I shared a common mutation (C826A,Leu276Ileu) and their phenotypic severity was correlated with the second allelic mutation. Ann Neurol 2003;53:537–542

Ataluren treatment of patients with nonsense mutation dystrophinopathy

Introduction: Dystrophinopathy is a rare, severe muscle disorder, and nonsense mutations are found in 13% of cases. Ataluren was developed to enable ribosomal readthrough of premature stop codons in nonsense mutation (nm) genetic disorders. Methods: Randomized, double‐blind, placebo‐controlled study; males ≥5 years with nm‐dystrophinopathy received study drug orally 3 times daily, ataluren 10, 10, 20 mg/kg (N = 57); ataluren 20, 20, 40 mg/kg (N = 60); or placebo (N = 57) for 48 weeks. The primary endpoint was change in 6‐Minute Walk Distance (6MWD) at Week 48. Results: Ataluren was generally well tolerated. The primary endpoint favored ataluren 10, 10, 20 mg/kg versus placebo; the week 48 6MWD Δ = 31.3 meters, post hoc P = 0.056. Secondary endpoints (timed function tests) showed meaningful differences between ataluren 10, 10, 20 mg/kg, and placebo. Conclusions: As the first investigational new drug targeting the underlying cause of nm‐dystrophinopathy, ataluren offers promise as a treatment for this orphan genetic disorder with high unmet medical need. Muscle Nerve 50: 477–487, 2014

Randomized, double-blind, placebo-controlled trial of phenylbutyrate in spinal muscular atrophy

Objective: To assess the efficacy of phenylbutyrate (PB) in patients with spinal muscular atrophy in a randomized, double-blind, placebo-controlled trial involving 10 Italian centers. Methods: One hundred seven children were assigned to receive PB (500 mg/kg/day) or matching placebo on an intermittent regimen (7 days on/7 days off) for 13 weeks. The Hammersmith functional motor scale (primary outcome measure), myometry, and forced vital capacity were assessed at baseline and at weeks 5 and 13. Results: Between January and September 2004, 107 patients aged 30 to 154 months were enrolled. PB was well tolerated, with only one child withdrawing because of adverse events. Mean improvement in functional score was 0.60 in the PB arm and 0.73 in placebo arm (p = 0.70). Changes in the secondary endpoints were also similar in the two study arms. Conclusions: Phenylbutyrate was not effective at the regimen, schedule, and duration used in this study.

Phenylbutyrate increases SMN gene expression in spinal muscular atrophy patients

Spinal muscular atrophy (SMA) is caused by insufficient levels of survival motor neuron (SMN) protein. Recently, we found that sodium 4-phenylbutyrate (PB), a well-tolerated FDA approved drug, enhances SMN gene expression in vitro. We provide here the first evidence that oral administration of PB (triButyrate®) significantly increases SMN expression in leukocytes of SMA patients. This finding provides a strong rationale to further investigate the effects of PB as also supported by preliminary clinical data.

Optimality score for the neurologic examination of the infant at 12 and 18 months of age

The aim of this study was to develop and validate a simple, quantifiable, neurologic examination for infants between 2 and 24 months of age. The assessment consists of 37 items, divided into 3 sections. The first section includes 26 items assessing cranial nerve function, posture, movements, tone, and reflexes; the second section of 8 items documents the development of motor function, and the third section of 3 items evaluates the state of behavior. We applied this assessment to a cohort of ninety-two 12-month-old infants and forty-three 18-month-old infants, with no known perinatal risk factors. The proforma presented has been designed according to the frequency distribution of the neurologic findings in this cohort. Each item is scored individually, and a global score is the sum of all individual scores. The quantitative score enhances the value of this examination, both in clinical practice and in research settings.