I1363T突变致人骨骼肌电压门控钠通道快失活受损的机制

探究人源骨骼肌电压门控钠通道hNav1.4 I1363T突变体导致患者出现先天性副肌强直症状的机制。 利用氨基酸序列比对,检测hNav1.4 I1363位点的保守性;将hNav1.4蛋白的羧基端融合荧光蛋白mCherry,利用共聚焦显微镜观察hNav1.4野生型与I1363T突变体蛋白的表达量与分布情况;通过全细胞电生理技术记录野生型与I1363T突变体的稳态激活及快失活参数,并进一步分析野生型与I1363T突变体的窗电流。 hNav1.4 I1363位点在各类钠通道中高度保守。野生型与I1363T突变体均能正常上膜,且表达量无明显差异。野生型与I1363T突变体的50%激活电压V_0.5 分别为（-29.08±0.24）mV和（-28.79±0.21）mV,斜率因子k分别为5.06±0.21和4.73±0.18（均P＞0.05）;野生型与I1363T突变体的50%失活电压V_0.5 分别为（-68.03±0.34）mV和（-59.01±0.26）mV,斜率因子k分别为4.55±0.21和5.24±0.23（均P＜0.05）,I1363T突变体的失活电压向去极化方向移动,且更为平缓。I1363T突变体形成的窗电流大于野生型的窗电流。 I1363T突变会导致hNav1.4慢失活受损,增加肌肉细胞兴奋性,导致肌强直的发生;而增大的窗电流使得钠离子在细胞内缓慢聚集,最终导致细胞兴奋性下降,引发肌无力。      

反复肺部感染及口腔黏膜溃疡

8岁女性患儿,因间断咳嗽、发热3年余,再发1月余入院。近1年反复出现口腔黏膜溃疡。体格检查发现右上背部皮肤色素脱失。外院多次查血常规和免疫功能正常。多次肺部CT提示肺部感染病灶,经抗感染治疗,发热咳嗽仍反复,右肺部病变持续存在,抗结核治疗无效。多次血常规检查发现粒细胞缺乏,行基因检测,确定为RTEL1基因纯合突变所致先天性角化不良(DC)。RTEL1基因突变的先天性角化不良患者易出现肺部并发症。由于RTEL1基因序列有高度可变性,突变位点很多,突变方式多样,且可以通过常染色体显性或隐性遗传方式遗传,因此其临床表现多样,易致漏诊及误诊。对不明原因反复肺部感染的患儿,应注意口腔、皮肤和指趾甲的检查并监测血常规以排除DC。DC目前无特效治疗,出现骨髓衰竭和肺功能衰竭时,造血干细胞移植和肺移植是目前唯一的治疗方法,雄激素及其衍生物对部分病人有效,针对端粒途径的靶向药物有望给DC患者带来希望。     

Severe congenital absence of skin in a preterm infant

A severe case of aplasia cutis congenita in a preterm infant is described. Although major problems with thermoregulation and fluid balance were anticipated, these parameters were relatively easy to control once the patient was stabilized. Meticulous skin care and rapid formation of a membranous-like fibrous tissue layer covering the denuded areas probably played an important role in minimizing excessive fluid and heat loss. The prognosis in aplasia cutis congenita is determined by the underlying associated anomalies, the severity of skin lesions and, in our case, the maturity of the infant who died from complications of prematurity.     

Novel mutations in the muscle chloride channel CLCN1 gene causing myotonia congenita in Spanish families

Mutations in the muscular voltage-dependent chloride channel gene (CLCN1), located at 7q35, lead to recessive and dominant myotonia congenita. We report four novel mutations identified in this gene, after clinical, electromyographic, and genetic studies performed on 13 unrelated families. Two of the four mutations (2512insCTCA and A218T) were identified in families with Thomsen’s disease, one (Q658X) in a family with Becker’s disease, and the fourth (R669C) in a presumably sporadic patient with the Becker phenotype. Although identification of the mutations allows us to establish some genotype/phenotype correlations, this does not wholly account for the clinical heterogenity and the inheritance patterns of the disease. Received: 27 June 1998 Received in revised form: 11 November 1998 Accepted: 16 November 1998     

先天性甲肥厚Ⅰ型一家系调查

报告先天性甲肥厚1个家系,2代共有3人患病,3例患者均有甲增厚,掌跖角化,掌跖多汗,局部摩擦可发生水疱和毛发稀疏等典型表现.先证者手、足背弥漫性角化过度,18只甲营养不良。     

Robin sequences and complexes: Causal heterogeneity and pathogenetic/phenotypic variability

Robin sequence has been the subject of numerous general papers and has also been cited in specific syndrome articles. Evidence is provided that the condition is not only causally heterogeneous but also pathogenetically and phenotypically variable, necessitating the use of the terms “Robin sequences” and “Robin complexes.” Am. J. Med. Genet. 84:311–315, 1999. © 1999 Wiley-Liss, Inc.     

A case of pachyonychia congenita with unusual manifestations: an unusual type or a new syndrome?

A 30‐year‐old man presented with lesions on his oral mucosa and soles. There were no similar complaints in his family members. The dermatological examination revealed follicular hyperkeratosis on his trunk and upper extremities and flesh‐colored, firm cystic lesions on his axillae. He had focal, painful, hyperkeratotic areas sited particularly on both his soles and palms. In addition to these, leukokeratosis and ulcerative areas on buccal, labial mucosa, tongue, and at corners of the mouth, and complete loss of teeth was observed. The proximal layering was revealed on all of his nails. The laboratory investigations produced normal results except the deficiency of immunoglobulin A. The psychiatric examination revealed mild mental retardation. Keratin gene (KRT6a, KRT6b, KRT16, and KRT17) mutations for pachyonychia congenita were negative. He got removable dental prosthesis because of inadequate alimentation. Squamous cell cancer developed on lower lip mucosa during follow‐up. We present an individual who had different nail dystrophy, epidermal cysts, mental retardation, blepharitis, complete loss of teeth, and negative keratin gene mutations for pachyonychia congenita and developed squamous cell cancer on the oral leukokeratosis lesions. We think that the present case may be an unusual new type of pachyonychia congenita.     

Wieacker‐Wolff syndrome,a distinctive phenotype of arthrogryposis multiplex congenita caused by a “de novo” ZC4H2 gene partial deletion

Unusual fetal arthrogryposis on ultrasound should draw attention to look for additional lower limb anomalies. Precise genetic counseling may be obtained from deletion on Xq11.2 as for ZC4H2 gene sequencing diagnostic for Wieacker‐Wolff syndrome.