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1.  Requirement of enhanced Survival Motoneuron protein imposed during neuromuscular junction maturation 
Spinal muscular atrophy is a common motor neuron disease caused by low survival motoneuron (SMN), a key protein in the proper splicing of genes. Restoring the protein is therefore a promising therapeutic strategy. Implementation of this strategy, however, depends on defining the temporal requirements for SMN. Here, we used controlled knockdown of SMN in transgenic mice to determine the precise postnatal stage requirements for this protein. Reducing SMN in neonatal mice resulted in a classic SMA-like phenotype. Unexpectedly, depletion of SMN in adults had relatively little effect. Insensitivity to low SMN emerged abruptly at postnatal day 17, which coincided with establishment of the fully mature neuromuscular junction (NMJ). Mature animals depleted of SMN eventually exhibited evidence of selective neuromuscular pathology that was made worse by traumatic injury. The ability to regenerate the mature NMJ in aged or injured SMN-depleted mice was grossly impaired, a likely consequence of the inability to meet the surge in demand for motoneuronal SMN that was seen in controls. Our results demonstrate that relative maturity of the NMJ determines the temporal requirement for the SMN protein. These observations suggest that the use of potent but potentially deleterious SMN-enhancing agents could be tapered in human patients once the neuromuscular system matures and reintroduced as needed to enhance SMN for remodeling aged or injured NMJs.
doi:10.1172/JCI72017
PMCID: PMC3904626  PMID: 24463453
2.  MPV17 Mutations Causing Adult-Onset Multisystemic Disorder With Multiple Mitochondrial DNA Deletions 
Archives of neurology  2012;69(12):1648-1651.
Objective
To identify the cause of an adult-onset multisystemic disease with multiple deletions of mitochondrial DNA (mtDNA).
Design
Case report.
Setting
University hospitals.
Patient
A 65-year-old man with axonal sensorimotor peripheral neuropathy, ptosis, ophthalmoparesis, diabetes mellitus, exercise intolerance, steatohepatopathy, depression, parkinsonism, and gastrointestinal dysmotility.
Results
Skeletal muscle biopsy revealed ragged-red and cytochrome-c oxidase–deficient fibers, and Southern blot analysis showed multiple mtDNA deletions. No deletions were detected in fibroblasts, and the results of quantitative polymerase chain reaction showed that the amount of mtDNA was normal in both muscle and fibroblasts. Exome sequencing using a mitochondrial library revealed compound heterozygous MPV17 mutations (p.LysMet88-89MetLeu and p.Leu143*), a novel cause of mtDNA multiple deletions.
Conclusions
In addition to causing juvenile-onset disorders with mtDNA depletion, MPV17 mutations can cause adult-onset multisystemic disease with multiple mtDNA deletions.
doi:10.1001/archneurol.2012.405
PMCID: PMC3894685  PMID: 22964873
3.  Mitochondrial Encephalomyopathy Due to a Novel Mutation in ACAD9 
JAMA neurology  2013;70(9):1177-1179.
IMPORTANCE
Mendelian forms of complex I deficiency are usually associated with fatal infantile encephalomyopathy. Application of “MitoExome” sequencing (deep sequencing of the entire mitochondrial genome and the coding exons of >1000 nuclear genes encoding the mitochondrial proteome) allowed us to reveal an unusual clinical variant of complex I deficiency due to a novel homozygous mutation in ACAD9. The patient had an infantile-onset but slowly progressive encephalomyopathy and responded favorably to riboflavin therapy.
OBSERVATION
A 13-year-old boy had exercise intolerance, weakness, and mild psychomotor delay. Muscle histochemistry showed mitochondrial proliferation, and biochemical analysis revealed severe complex I deficiency (15% of normal). The level of complex I holoprotein was reduced as determined by use of Western blot both in muscle (54%) and in fibroblasts (57%).
CONCLUSIONS AND RELEVANCE
The clinical presentation of complex I deficiency due ACAD9 mutations spans from fatal infantile encephalocardiomyopathy to mild encephalomyopathy. Our data support the notion that ACAD9 functions as a complex I assembly protein. ACAD9 is a flavin adenine dinucleotide–containing flavoprotein, and treatment with riboflavin is advisable.
doi:10.1001/jamaneurol.2013.3197
PMCID: PMC3891824  PMID: 23836383
4.  Historical Perspective on Mitochondrial Medicine 
Developmental disabilities research reviews  2010;16(2):10.1002/ddrr.102.
In this review, we trace the origins and follow the development of mitochondrial medicine from the pre-molecular era (1962-1988) based on clinical clues, muscle morphology, and biochemistry into the molecular era that started in 1988 and is still advancing at a brisk pace. We have tried to stress conceptual advances, such as endosymbiosis, uniparental inheritance, intergenomic signaling and its defects, and mitochondrial dynamics. We hope that this historical review also provides an update on mitochondrial medicine, although we fully realize that the speed of progress in this area makes any such endeavor akin to writing on water.
doi:10.1002/ddrr.102
PMCID: PMC3839238  PMID: 20818724
mitochondria; mitochondrial DNA; maternal inheritance; intergenomic signaling
5.  Next-generation sequencing reveals DGUOK mutations in adult patients with mitochondrial DNA multiple deletions 
Brain  2012;135(11):3404-3415.
The molecular diagnosis of mitochondrial disorders still remains elusive in a large proportion of patients, but advances in next generation sequencing are significantly improving our chances to detect mutations even in sporadic patients. Syndromes associated with mitochondrial DNA multiple deletions are caused by different molecular defects resulting in a wide spectrum of predominantly adult-onset clinical presentations, ranging from progressive external ophthalmoplegia to multi-systemic disorders of variable severity. The mutations underlying these conditions remain undisclosed in half of the affected subjects. We applied next-generation sequencing of known mitochondrial targets (MitoExome) to probands presenting with adult-onset mitochondrial myopathy and harbouring mitochondrial DNA multiple deletions in skeletal muscle. We identified autosomal recessive mutations in the DGUOK gene (encoding mitochondrial deoxyguanosine kinase), which has previously been associated with an infantile hepatocerebral form of mitochondrial DNA depletion. Mutations in DGUOK occurred in five independent subjects, representing 5.6% of our cohort of patients with mitochondrial DNA multiple deletions, and impaired both muscle DGUOK activity and protein stability. Clinical presentations were variable, including mitochondrial myopathy with or without progressive external ophthalmoplegia, recurrent rhabdomyolysis in a young female who had received a liver transplant at 9 months of age and adult-onset lower motor neuron syndrome with mild cognitive impairment. These findings reinforce the concept that mutations in genes involved in deoxyribonucleotide metabolism can cause diverse clinical phenotypes and suggest that DGUOK should be screened in patients harbouring mitochondrial DNA deletions in skeletal muscle.
doi:10.1093/brain/aws258
PMCID: PMC3501975  PMID: 23043144
DGUOK; mitochondrial DNA instability; autosomal recessive progressive external ophthalmoplegia; multiple mitochondrial DNA deletions
6.  Molecular Diagnosis of Infantile Mitochondrial Disease with Targeted Next-Generation Sequencing 
Science translational medicine  2012;4(118):118ra10.
Advances in next-generation sequencing (NGS) promise to facilitate diagnosis of inherited disorders. While in research settings NGS has pinpointed causal alleles using segregation in large families, the key challenge for clinical diagnosis is application to single individuals. To explore its diagnostic utility, we performed targeted NGS in 42 unrelated infants with clinical and biochemical evidence of mitochondrial oxidative phosphorylation disease, who were refractory to traditional molecular diagnosis. These devastating mitochondrial disorders are characterized by phenotypic and genetic heterogeneity, with over 100 causal genes identified to date. We performed “MitoExome” sequencing of the mitochondrial DNA (mtDNA) and exons of ~1000 nuclear genes encoding mitochondrial proteins and prioritized rare mutations predicted to disrupt function. Since patients and controls harbored a comparable number of such heterozygous alleles, we could not prioritize dominant acting genes. However, patients showed a five-fold enrichment of genes with two such mutations that could underlie recessive disease. In total, 23/42 (55%) patients harbored such recessive genes or pathogenic mtDNA variants. Firm diagnoses were enabled in 10 patients (24%) who had mutations in genes previously linked to disease. 13 patients (31%) had mutations in nuclear genes never linked to disease. The pathogenicity of two such genes, NDUFB3 and AGK, was supported by cDNA complementation and evidence from multiple patients, respectively. The results underscore the immediate potential and challenges of deploying NGS in clinical settings.
doi:10.1126/scitranslmed.3003310
PMCID: PMC3523805  PMID: 22277967
7.  Clinical and genetic spectrum of mitochondrial neurogastrointestinal encephalomyopathy 
Brain  2011;134(11):3326-3332.
Mitochondrial neurogastrointestinal encephalomyopathy is a rare multisystemic autosomic recessive disorder characterized by: onset typically before the age of 30 years; ptosis; progressive external ophthalmoplegia; gastrointestinal dysmotility; cachexia; peripheral neuropathy; and leucoencephalopathy. The disease is caused by mutations in the TYMP gene encoding thymidine phosphorylasethymine phosphorylase. Anecdotal reports suggest that allogeneic haematopoetic stem cell transplantation may be beneficial for mitochondrial neurogastrointestinal encephalomyopathy, but is associated with a high mortality. After selecting patients who fulfilled the clinical criteria for mitochondrial neurogastrointestinal encephalomyopathy and had severe thymidine phosphorylase deficiency in the buffy coat (<10% of normal activity), we reviewed their medical records and laboratory studies. We identified 102 patients (50 females) with mitochondrial neurogastrointestinal encephalomyopathy and an average age of 32.4 years (range 11–59 years). We found 20 novel TYMP mutations. The average age-at-onset was 17.9 years (range 5 months to 35 years); however, the majority of patients reported the first symptoms before the age of 12 years. The patient distribution suggests a relatively high prevalence in Europeans, while the mutation distribution suggests founder effects for a few mutations, such as c.866A>G in Europe and c.518T>G in the Dominican Republic, that could guide genetic screening in each location. Although the sequence of clinical manifestations in the disease varied, half of the patients initially had gastrointestinal symptoms. We confirmed anecdotal reports of intra- and inter-familial clinical variability and absence of genotype–phenotype correlation in the disease, suggesting genetic modifiers, environmental factors or both contribute to disease manifestations. Acute medical events such as infections often provoked worsening of symptoms, suggesting that careful monitoring and early treatment of intercurrent illnesses may be beneficial. We observed endocrine/exocrine pancreatic insufficiency, which had not previously been reported. Kaplan–Meier analysis revealed significant mortality between the ages of 20 and 40 years due to infectious or metabolic complications. Despite increasing awareness of this illness, a high proportion of patients had been misdiagnosed. Early and accurate diagnosis of mitochondrial neurogastrointestinal encephalomyopathy, together with timely treatment of acute intercurrent illnesses, may retard disease progression and increase the number of patients eligible for allogeneic haematopoetic stem cell transplantation.
doi:10.1093/brain/awr245
PMCID: PMC3212717  PMID: 21933806
mitochondrial disease; MNGIE; encephalomyopathy; TYMP; BMT
8.  SAFA: A new measure to evaluate psychiatric symptoms detected in a sample of children and adolescents affected by eating disorders. Correlations with risk factors 
In order to evaluate the psychiatric symptoms associated with a diagnosis of eating disorders (ED) we have administered a new psychometric instrument: the Self Administrated Psychiatric Scales for Children and Adolescents (SAFA) test. SAFA was administered to a cohort of 97 patients, aged from 8.8 to 18, with an ED diagnosis. Age, body mass index (BMI) and BMI standard deviation score were analyzed. Furthermore, while looking for linkable risk factors, we evaluated other data that took an influence over the SAFA profile, like parental separation and family components’ number. Compared to the range of statistical normality (based on Italian population), patients with bulimia nervosa or binge-eating disorder showed higher and pathologic values in specific subscales. When analyzing sex, males showed more pathologic values in most anxiety-related, obsessiveness–compulsiveness-related and insecurity subscales. A correlation among age, BMI and specific subscales (low self esteem, psychological aspects) emerged in participants with anorexia nervosa. In order to plan more appropriate diagnostic and therapeutic approaches in children or adolescents suffering from ED, the SAFA test can be an important instrument to evaluate psychiatric symptoms. Therefore, we propose to include this useful, simple self-administered test as a new screening tool for ED diagnosis.
PMCID: PMC2695231  PMID: 19557115
psychiatric comorbidity; anorexia nervosa; bulimia nervosa; binge-eating disorder; SAFA test

Results 1-8 (8)