Tongue pressure during swallowing is decreased in patients with Duchenne muscular dystrophy

Although dysphagia is a life-threatening problem in patients with Duchenne muscular dystrophy (DMD), the pathophysiology of oral stage dysphagia is yet to be understood. The present study investigated the tongue motor deficit during swallowing in patients with DMD and its relationship with disease-specific palatal morphology. Tongue pressure during swallowing water was recorded in 11 male patients with DMD and 11 age- and sex-matched healthy subjects using an intra-oral sensor with five measuring points, and the state of tongue pressure production was compared between the groups. Palatal morphology was assessed by a non-contact three-dimensional scanner on maxillary plaster models. In patients with DMD, the normal sequential order of tongue-palate contact was lost and the maximal magnitude and integrated value of tongue pressure on the mid-anterior part of palate were smaller than those in healthy subjects. The width of the palate in patients was greater than that in healthy subjects and the depth of the palate in patients had a negative correlation with tongue pressure magnitude on the median palate. Our results suggested that the deteriorated tongue motor kinetics prevented tongue movement during swallowing that was appropriate for the depth of the palate and affects the state of tongue pressure production during swallowing.     

Assessment of intramuscular lipid and metabolites of the lower leg using magnetic resonance spectroscopy in boys with Duchenne muscular dystrophy

The purpose of this study was to use proton magnetic resonance spectroscopy to assess intramuscular lipid and metabolites of lower leg muscles in boys with Duchenne muscular dystrophy (DMD) and determine its relationship with strength and functional ability. Spectroscopic measurements were obtained from four muscles of the lower leg in 25 boys with DMD (9.2 ± 3.1 years) and 10 healthy boys (10.2 ± 2.6 years). Lipid fractions and metabolite concentrations were also determined. Muscle strength, a timed functional test, and the Modified Brooke Lower Extremity Functional Scale were also determined. Lipid fractions were higher (p < 0.01) for the DMD group than healthy subjects for all muscles, and lipid fraction was found to be greater in the older DMD boys. The peroneal muscle demonstrated a significant difference in lipid fraction in all DMD age groups. Lipid fractions in all muscles correlated with functional measures (r = 0.52–0.70, p < 0.001), with smaller inverse correlations with the strength measure (r = −0.36 to −0.56, p < 0.05). These findings provide quantifiable information regarding intramuscular lipid and metabolite levels of different muscles across various age groups in boys with DMD and may be used in determining the effect of interventions in future clinical trials.     

Atypical phenotype in two patients with LAMA2 mutations

Congenital muscular dystrophy type 1A is caused by mutations in the LAMA2 gene, which encodes the α2-chain of laminin. We report two patients with partial laminin-α2 deficiency and atypical phenotypes, one with almost exclusive central nervous system involvement (cognitive impairment and refractory epilepsy) and the second with marked cardiac dysfunction, rigid spine syndrome and limb-girdle weakness. Patients underwent clinical, histopathological, imaging and genetic studies. Both cases have two heterozygous LAMA2 variants sharing a potentially pathogenic missense mutation c.2461A>C (p.Thr821Pro) located in exon 18. Brain MRI was instrumental for the diagnosis, since muscular examination and motor achievements were normal in the first patient and there was a severe cardiac involvement in the second. The clinical phenotype of the patients is markedly different which could in part be explained by the different combination of mutations types (two missense versus a missense and a truncating mutation).     

When a mid-intronic variation of DMD gene creates an ESE site

Duchenne and Becker muscular dystrophy are X-linked allelic disorders caused by mutations in the DMD gene. The majority (65%) of these mutations are intragenic deletions/duplications that often lead to frameshift errors. Among the remaining ones, we find the mid-intronic mutations that usually create cryptic exons by activating potential splice sites. In this report, we identified, in a Becker muscular dystrophy patient, a mid-intronic variation that creates two ESE sites in intron 26 of DMD gene resulting in the insertion of a new cryptic exon in mRNA. Despite the out of frame character of this mutation, we observed the production of a reduced amount of full-size dystrophin which could be explained by the alternation between normal and altered splicing of dystrophin mRNA in this patient.To our knowledge, this is the first case report describing this novel pathogenic mechanism of mid-intronic variations of DMD gene.     

Total intravenous anesthesia for aortic aneurysm replacement surgery in a patient with limb-girdle dystrophy

We report the anesthetic management with total intravenous anesthesia of a 61-year-old male diagnosed with limb-girdle muscular dystrophy admitted for replacement of ascending aorta due to an aortic aneurysm. Limb-girdle muscular dystrophy belongs to a genetically heterogeneous group of muscular dystrophies involving shoulder and hip girdles. Although the risk of malignant hyperthermia does not seem to be increased in these patients compared with the general population, the exposure to inhaled anesthetics and succinylcholine should probably be avoided because these patients have a predisposition to hyperkalemia and rhabdomyolysis. We chose to use total intravenous anesthesia with propofol, remifentanil and muscle relaxants to reduce oxygen consumption, and later to reduce the doses of propofol and remifentanil. The combination of a carefully planned anesthetic strategy, anesthetic depth, and neuromuscular blockade monitoring is explained.     

视网膜色素变性发病机制及治疗进展

视网膜色素变性（retintis pigmentosa,RP）是指以进行性感光细胞及色素上皮功能丧失为共同表现的遗传性、退行性的疾病,RP是主要的致盲性眼病。其遗传方式包括X连锁遗传、常染色体隐性或者显性遗传,也有散发。临床表现为典型的三联征:骨细胞样色素沉着、视网膜血管缩窄和视盘蜡样苍白。RP具有高度的基因异质性(多个突变位点引起同一疾病）及表型异质性。本文对RP的发病机制和治疗方法进行简要综述。     

Quantitative and qualitative alterations of dystrophin are expressed in muscle cell cultures of Xp21 muscular dystrophy patients (Duchenne and Becker type)

The authors studied skeletal muscle cell cultures from four control subjects, two patients with Duchenne muscular dystrophy, two Duchenne carriers and three patients with Becker muscular dystrophy with different phenotypes. Western blotting was performed on well-differentiated myotubes and compared with the results obtained in muscle tissue. In all cultures the band of dystrophin closely corresponded to the one observed in muscle tissue: both quantitative and qualitative defects were observed. This confirms the early expression of the Xp21 gene defect in uninnervated muscle cultures and supports the usefulness of muscle cultures both in diagnostic procedure and as a model to study the disease.     

MERTK mutation update in inherited retinal diseases

MER tyrosine kinase (MERTK) encodes a surface receptor localized at the apical membrane of the retinal pigment epithelium. It plays a critical role in photoreceptor outer segment internalization prior to phagocytosis. Mutations in MERTK have been associated with severe autosomal recessive retinal dystrophies in the RCS rat and in humans. We present here a comprehensive review of all reported MERTK disease causing variants with the associated phenotype. In addition, we provide further data and insights of a large cohort of 1,195 inherited retinal dystrophies (IRD) index cases applying state‐of‐the‐art genotyping techniques and summarize current knowledge. A total of 79 variants have now been identified underlying rod‐cone dystrophy and cone‐rod dystrophy including 11 novel variants reported here. The mutation spectrum in MERTK includes 33 missense, 12 nonsense, 12 splice defects, 12 small deletions, 2 small insertion–deletions, 3 small duplications, and 2 exonic and 3 gross deletions. Altogether, mutations in MERTK account for ～2% of IRD cases with a severe retinal phenotype. These data are important for current and future therapeutic trials including gene replacement therapy or cell‐based therapy.