LTBP4, SPP1, and CD40 Variants: Genetic Modifiers of Duchenne Muscular Dystrophy Analyzed in Serbian Patients.

BACKGROUND: Clinical course variability in Duchenne muscular dystrophy (DMD) is partially explained by the mutation location in the DMD gene and variants in modifier genes. We assessed the effect of the SPP1, CD40, and LTBP4 genes and DMD mutation location on loss of ambulation (LoA). METHODS: SNPs in SPP1-rs28357094, LTBP4-rs2303729, rs1131620, rs1051303, rs10880, and CD40-rs1883832 were genotyped, and their effect was assessed by survival and hierarchical cluster analysis. RESULTS: Patients on glucocorticoid corticosteroid (GC) therapy experienced LoA one year later (p = 0.04). The modifying effect of SPP1 and CD40 variants, as well as LTBP4 haplotypes, was not observed using a log-rank test and multivariant Cox regression analysis. Cluster analysis revealed two subgroups with statistical trends in differences in age at LoA. Almost all patients in the cluster with later LoA had the protective IAAM LTBP4 haplotype and statistically significantly fewer CD40 genotypes with harmful T allele and "distal" DMD mutations. CONCLUSIONS: The modifying effect of SPP1, CD40, and LTBP4 was not replicated in Serbian patients, although our cohort was comparable in terms of its DMD mutation type distribution, SNP allele frequencies, and GC-positive effect with other European cohorts. Cluster analysis may be able to identify patient subgroups carrying a combination of the genetic variants that modify LoA.

Biallelic ADPRHL2 mutations in complex neuropathy affect ADP ribosylation and DNA damage response.

ADP ribosylation is a reversible posttranslational modification mediated by poly(ADP-ribose)transferases (e.g., PARP1) and (ADP-ribosyl)hydrolases (e.g., ARH3 and PARG), ensuring synthesis and removal of mono-ADP-ribose or poly-ADP-ribose chains on protein substrates. Dysregulation of ADP ribosylation signaling has been associated with several neurodegenerative diseases, including Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease. Recessive ADPRHL2/ARH3 mutations are described to cause a stress-induced epileptic ataxia syndrome with developmental delay and axonal neuropathy (CONDSIAS). Here, we present two families with a neuropathy predominant disorder and homozygous mutations in ADPRHL2 We characterized a novel C26F mutation, demonstrating protein instability and reduced protein function. Characterization of the recurrent V335G mutant demonstrated mild loss of expression with retained enzymatic activity. Although the V335G mutation retains its mitochondrial localization, it has altered cytosolic/nuclear localization. This minimally affects basal ADP ribosylation but results in elevated nuclear ADP ribosylation during stress, demonstrating the vital role of ADP ribosylation reversal by ARH3 in DNA damage control.

Phenotypic and genetic spectrum of patients with limb-girdle muscular dystrophy type 2A from Serbia.

Limb-girdle muscular dystrophy (LGMD) type 2A (calpainopathy) is an autosomal recessive disease caused by mutation in the CAPN3 gene. The aim of this study was to examine genetic and phenotypic features of Serbian patients with calpainopathy. The study comprised 19 patients with genetically confirmed calpainopathy diagnosed at the Neurology Clinic, Clinical Center of Serbia and the Clinic for Neurology and Psychiatry for Children and Youth in Belgrade, Serbia during a ten-year period. Eighteen patients in this cohort had c.550delA mutation, with nine of them being homozygous. In majority of the patients, disease started in childhood or early adulthood. The disease affected shoulder girdle - upper arm and pelvic girdle - thigh muscles with similar frequency, with muscles of lower extremities being more severely impaired. Facial and bulbar muscles were spared. All patients in this cohort, except two, remained ambulant. None of the patients had cardiomyopathy, while 21% showed mild conduction defects. Respiratory function was mildly impaired in 21% of patients. Standard muscle histopathology showed myopathic and dystrophic pattern. In conclusion, the majority of Serbian LGMD2A patients have the same mutation and similar phenotype.

Further developments with antisense treatment for myasthenia gravis.

We present further developments in the study of the antisense oligonucleotide EN101. Ongoing in vitro and in vivo studies demonstrate that EN101 is a TLR9-specific ligand that can suppress pro-inflammatory functions and shift nuclear factor kappa B (NF-κB) from the pro-inflammatory canonical pathway to the anti-inflammatory alternative pathway, which results in decreases acetylcholinesterase (AChE) activity. Preliminary results of a double-blinded phase II cross-over study compared 10, 20, and 40 mg EN101 administered to patients with myasthenia gravis. Patients were randomly assigned to one of three treatment groups in weeks 1, 3, and 5 and received their pretreatment dose of pyridostigmine in weeks 2 and 4. Thus far, all doses show a decrease in QMG scores, with a greater response to higher doses.

Targeted next-generation sequencing of a 12.5 Mb homozygous region reveals ANO10 mutations in patients with autosomal-recessive cerebellar ataxia.

Autosomal-recessive cerebellar ataxias comprise a clinically and genetically heterogeneous group of neurodegenerative disorders. In contrast to their dominant counterparts, unraveling the molecular background of these ataxias has proven to be more complicated and the currently known mutations provide incomplete coverage for genotyping of patients. By combining SNP array-based linkage analysis and targeted resequencing of relevant sequences in the linkage interval with the use of next-generation sequencing technology, we identified a mutation in a gene and have shown its association with autosomal-recessive cerebellar ataxia. In a Dutch consanguineous family with three affected siblings a homozygous 12.5 Mb region on chromosome 3 was targeted by array-based sequence capture. Prioritization of all detected sequence variants led to four candidate genes, one of which contained a variant with a high base pair conservation score (phyloP score: 5.26). This variant was a leucine-to-arginine substitution in the DUF 590 domain of a 16K transmembrane protein, a putative calcium-activated chloride channel encoded by anoctamin 10 (ANO10). The analysis of ANO10 by Sanger sequencing revealed three additional mutations: a homozygous mutation (c.1150_1151del [p.Leu384fs]) in a Serbian family and a compound-heterozygous splice-site mutation (c.1476+1G>T) and a frameshift mutation (c.1604del [p.Leu535X]) in a French family. This illustrates the power of using initial homozygosity mapping with next-generation sequencing technology to identify genes involved in autosomal-recessive diseases. Moreover, identifying a putative calcium-dependent chloride channel involved in cerebellar ataxia adds another pathway to the list of pathophysiological mechanisms that may cause cerebellar ataxia.

Childhood cerebral X-linked adrenoleukodystrophy more than 5 years after hematopoietic cell transplantation: the first case from Serbia and southeastern Europe.

We report the clinical course, brain magnetic resonance imaging (MRI), and proton magnetic resonance spectroscopy findings in a boy with childhood cerebral X-linked adrenoleukodystrophy whose neurological disease keeps progressing more than 5 years after conventional hematopoietic cell transplantation with full donor-derived engraftment accomplishment. The described clinical and radiological findings follow all phases of this childhood cerebral X-linked adrenoleukodystrophy: from the clinically asymptomatic pretransplant stage to the present day. This is the first patient not only from Serbia but from the entire area of Southeastern Europe who underwent hematopoietic cell transplantation for childhood cerebral X-linked adrenoleukodystrophy. The presented disease course and the posttransplant outcome in the only case of transplanted adrenoleukodystrophy from Serbia enhances the overwhelming appeal for better X-linked adrenoleukodystrophy screening, earlier disease detection, and contributes to the well-known anticipation of the refined hematopoietic cell transplantation eligibility criteria in future adrenoleukodystrophy treatment.

Eosinophilic myositis as presenting symptom in gamma-sarcoglycanopathy.

The patient reported here presented with first symptoms at the age of 10 showing an abnormal gait, calf hypertrophy and winged scapulae. She was diagnosed with eosinophilic myositis after muscle biopsy. A second muscle biopsy at the age of 20 and subsequent genetic testing, however, revealed the underlying condition of a primary gamma-sarcoglycanopathy, or LGMD2C. To our knowledge, this is the first LGMD2C patient reported who initially presented with eosinophilic myositis. Eosinophilia has been reported previously in patients with Calpainopathy and Becker Muscular Dystrophy and might be an early, but transient feature of a wider range of muscular dystrophies.