Durmuş Hacer, Ayhan Özgecan, Çırak Sebahattin, Deymeer Feza, Parman Yeşim, Franke Andre, Eiber Nane, Chevessier Frederic, Schlötzer-Schrehardt Ursula, Clemen Christoph S, Hashemolhosseini Said, Schröder Rolf, Hemmrich-Stanisak Georg, Tolun Aslıhan, Serdaroğlu-Oflazer Piraye
From the Department of Neurology (H.D., F.D., Y.P., P.S.-O.), Faculty of Medicine, Istanbul University; Department of Molecular Biology and Genetics (Ö.A., A.T.), Boğaziçi University, Istanbul, Turkey; Children's National Medical Center (S.Ç.), Research Center for Genetic Medicine, Washington, DC; Department of Pediatrics, Institute for Human Genetics, and Center for Molecular Medicine, University Hospital Cologne; Institute of Clinical Molecular Biology (A.F., G.H.-S.), Christian-Albrechts-University of Kiel; Institute of Biochemistry (N.E., S.H.), Institute of Neuropathology (F.C., R.S.), and Department of Ophthalmology (U.S.-S.), Friedrich-Alexander-University of Erlangen-Nuremberg; and Center for Biochemistry, Institute of Biochemistry I, Medical Faculty (C.S.C.), University of Cologne, Germany.
Neurology. 2016 Aug 23;87(8):799-805. doi: 10.1212/WNL.0000000000003004. Epub 2016 Jul 20.
To assess the clinical, genetic, and myopathologic findings in 2 cousins with lack of desmin, the response to salbutamol in one patient, and the neuromuscular endplate pathology in a knock-in mouse model for recessive desminopathy.
We performed clinical investigations in the patients, genetic studies for linkage mapping, exome sequencing, and qPCR for transcript quantification, assessment of efficacy of (3-month oral) salbutamol administration by muscle strength assessment, 6-minute walking test (6MWT), and forced vital capacity, analysis of neuromuscular endplate pathology in a homozygous R349P desmin knock-in mouse by immunofluorescence staining of the hind limb muscles, and quantitative 3D morphometry and expression studies of acetylcholine receptor genes by quantitative PCR.
Both patients had infantile-onset weakness and fatigability, facial weakness with bilateral ptosis and ophthalmoparesis, generalized muscle weakness, and a decremental response over 10% on repetitive nerve stimulation. Salbutamol improved 6MWT and subjective motor function in the treated patient. Genetic analysis revealed previously unreported novel homozygous truncating desmin mutation c.345dupC leading to protein truncation and consequent fast degradation of the mutant mRNA. In the recessive desminopathy mouse with low expression of the mutant desmin protein, we demonstrated fragmented motor endplates with increased surface areas, volumes, and fluorescence intensities in conjunction with increased α and γ acetylcholine receptor subunit expression in oxidative soleus muscle.
The patients were desmin-null and had myopathy, cardiomyopathy, and a congenital myasthenic syndrome. The data from man and mouse demonstrate that the complete lack as well as the markedly decreased expression of mutant R349P desmin impair the structural and functional integrity of neuromuscular endplates.
评估2名缺乏结蛋白的堂兄弟的临床、遗传和肌病理表现，1例患者对沙丁胺醇的反应，以及隐性结蛋白病敲入小鼠模型中的神经肌肉终板病理。
我们对患者进行了临床研究，进行了连锁图谱分析的基因研究、外显子组测序和转录本定量的qPCR，通过肌肉力量评估、6分钟步行试验（6MWT）和用力肺活量评估（3个月口服）沙丁胺醇给药的疗效，通过后肢肌肉免疫荧光染色分析纯合R349P结蛋白敲入小鼠的神经肌肉终板病理，并通过定量PCR对乙酰胆碱受体基因进行定量3D形态计量学和表达研究。
两名患者均有婴儿期起病的肌无力和疲劳、伴有双侧上睑下垂和眼肌麻痹的面部肌无力、全身肌无力，以及重复神经刺激时递减反应超过10%。沙丁胺醇改善了治疗患者的6MWT和主观运动功能。基因分析揭示了先前未报道的新型纯合截短结蛋白突变c.345dupC，导致蛋白质截短并随之导致突变mRNA快速降解。在突变结蛋白低表达的隐性结蛋白病小鼠中，我们证明氧化比目鱼肌中运动终板碎片化，表面积、体积和荧光强度增加，同时α和γ乙酰胆碱受体亚基表达增加。
患者为结蛋白缺失型，患有肌病、心肌病和先天性肌无力综合征。人和小鼠的数据表明，突变R349P结蛋白的完全缺失以及明显降低的表达损害了神经肌肉终板的结构和功能完整性。
