The Gene of Megalencephalic Leukoencephalopathy with Subcortical Cysts is Mapped on Chromosome 22q13.3 with 250 kb Interval

Objective: Vacuolating megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a recently described syndrome with autosomal recessive mode of inheritance. Its possible gene was located on chromosomal 22q tel with 3-cM. The purpose of this study was to narrow down the genetical distance on chromosomal 22q tel with MLC. Methods: Thirty-nine MLC patients in 33 families were collected,and the linkage analysis and haplotype analysis of twelve informative families were done, using seven microsatellite markers and four SNP markers. Results: The maximum tow-point LOD score for marker 355c18 was 6.65 at recombination fraction 0.02. The haplotype analysis narrowed down the critical region of MLC to 250 kb on chromosomal 22q tel. Conclusion: One of the causing genes of MLC was located on chromosomal 22q tel with 250 kb. Four candidate genes were considered. The heterogeneity of one informative family indicated possible existence of a second locus for MLC.

Megalencephalic Leukoencephalopathy with Subcortical Cysts-a New Child Leukoencephalopathy

Here we review a new variety of leukoencephalopathy with infantile megalencephaly and discrepant clinical course (MLC, MIM: 604004). These children had megalencephaly in the first year of life, with or without mild delay of motor function and/or seizures. After a few years, motor handicap was slowly progressive with unsteady gait, serious cerebellar ataxia and mild plasticity. Eventually most of patients were confined to a wheelchair. Meanwhile mental development was relatively preserved, although the learning problems was increased from the midway of elementary school. Most of patients had tonic-clonic seizure and some might advance to status epilepticus. Antiepileptic drugs may effectively control seizure. The disorders of known metabolic defects were excluded. Neurophysiological examination showed that EEG had interictal epileptic discharges on the generalized slow wave background in most patients. The cerebral white matter had diffuse abnormality, with swelling of white matter, and cysts in the frontoparietal and anterior-temporal lobes on MRI examination. Some central white matter structures were spared, such as corpus callosum. The severity of lesions on MRI is inconsistent with the clinical signs. Pathogenesis of this disease was unknown. The pathological findings found a spongiform leukoencephalopathy due to myelin splitting and intramyelinic vacuole formation but without myelin loss. This disease had probably an autosomal recessive inheritance. The gene KIAA027 on 22qtel was responsible for MLC.

Identification in Chinese patients with GLIALCAM mutations of megalencephalic leukoencephalopathy with subcortical cysts and brain pathological study on Glialcam knock-in mouse models

Background Megalencephalic leukoencephalopathy with subcortical cysts(MLC)is a rare neurological degenerative disorder caused by the mutations of MLC1 or GLIALCAM with autosomal recessive or autosomal dominant inheritance and a different prognosis,characterized by macrocephaly,delayed motor and cognitive development,and bilateral abnormal signals in cerebral white matter(WM)with or without cysts on magnetic resonance imaging(MRI).This study aimed to reveal the clinical and genetic features of MLC patients with GLIALCAM mutations and to explore the brain pathological characteristics and prognosis of mouse models with different modes of inheritance.Methods Clinical information and peripheral venous blood were collected from six families.Genetic analysis was performed by Sanger sequencing of GLIALCAM.Glialcam^(Arg92Trp/+)and Glialcam^(Lys68Met/Thr132Asn)mouse models were generated based on mutations from patients(c.274C>T(p.Arg92Trp)(c.203A>T(p.Lys68Met),and c.395C>A(p.Thr132Asn))).Brain pathologies of the mouse models at different time points were analyzed.Results Six patients were clinically diagnosed with MLC.Of the six patients,five(Pt1-Pt5)presented with a heterozygous mutation in GLIALCAM(c.274C>T(p.Arg92Trp)or c.275G>C(p.Arg92Pro))and were diagnosed with MLC2B;the remaining patient(Pt6)with two compound heterozygous mutations in GLIALCAM(c.203A>T(p.Lys68Met)and c.395C>A(p.Thr132Asn))was diagnosed with MLC2A.The mutation c.275C>G(p.Arg92Pro)has not been reported before.Clinical manifestations of the patient with MLC2A(Pt6)progressed with regression,whereas the course of the five MLC2B patients remained stable or improved.The Glialcam^(Arg92Trp/+)and Glialcam^(Lys68Met/Thr132Asn)mouse models showed vacuolization in the anterior commissural WM at 1 month of age and vacuolization in the cerebellar WM at 3 and 6 months,respectively.At 9 months,the vacuolization of the GlialcamiLys68Met/Thr132Asn mouse model was heavier than that of the Glialcam^(Arg92Trp/+)mouse model.Decreased expression of Glialcam in Glialcam^(Arg92Trp/+)and Glialcam^(Lys68Met/Thr132Asn)mice may contribute to the vacuolization.Conclusions Clinical and genetic characterization of patients with MLC and GLIALCAM mutations revealed a novel mutation,expanding the spectrum of GLIALCAM mutations.The first Glialcam mouse model with autosomal recessive inheritance and a new Glialcam mouse model with autosomal dominant inheritance were generated.The two mouse models with different modes of inheritance showed different degrees of brain pathological features,which were consistent with the patients'phenotype and further confirmed the pathogenicity of the corresponding mutations.

巨脑性白质脑病伴皮层下囊肿一家系MLC1基因突变分析

目的通过对巨脑性白质脑病伴皮层下囊肿(MLC)一家系的分析,确定其MLC1基因的改变及遗传特征。方法收集先证者及其家系成员的临床资料,采用聚合酶链反应(PCR)和DNA直接测序方法进行MLC1基因突变检测,确定基因突变位点,明确MLC诊断。结果本家系先证者临床符合MLC诊断。测序结果发现两个基因位点改变c.218G>A(p.Gly73Glu)和IVS9-1G>C。患儿为复合杂合突变致病,其c.218G>A突变来自母亲,IVS9-1G>C突变来自父亲,其父母均为表型正常携带者。结论此家系中1例中国MLC患儿存在MLC1基因复合杂合突变,一个是错义突变,另一个是剪接位点突变。

中国伴皮质下囊肿的巨脑性白质脑病携带者筛查专家共识

伴皮质下囊肿的巨脑性白质脑病(MLC)是一种罕见的遗传性神经系统疾病,由常染色体隐性或显性方式遗传。MLC主要临床表现为婴儿期出现的大头畸形、运动发育迟缓、智能减退、癫痫及渐进性神经功能障碍等。目前,MLC的治疗缺乏特效药物,给家庭和社会带来巨大的负担。因此,开展对MLC携带者进行筛查,降低患儿出生率是防控关键。该专家共识的目的是指导对MLC携带者进行筛查,提供降低生育风险的遗传咨询和干预措施,为临床工作提供帮助,促进对MLC的规范化防控。

伴皮层下囊肿的巨脑性白质脑病GLIALCAM突变患者临床遗传学及影像学研究

目的分析GLIALCAM突变伴皮层下囊肿的巨脑性白质脑病(megalencephalic leukoencephalopathy with subcortical cysts,MLC)患儿临床遗传学及头颅影像学特征,为准确的遗传咨询和产前诊断打下基础。方法收集6例MLC先证者及家系临床资料,评估患儿头颅MRI,靶向捕获二代测序行GLIALCAM突变检测,分析影像学特征与基因型关系。结果患儿多具有巨颅及典型MLC头颅MRI改变,伴智力运动发育迟缓、倒退及孤独症样行为,临床诊断MLC。6例患儿发现4个错义突变,c.274C>T(p.Arg92Trp),c.275G>C(p.Arg92Pro),c.203A>T(p.Lys68Met)和c.395C>A(p.Thr132Asn),其中c.275G>C(p.Arg92Pro)为未报道新突变,5例患儿为杂合突变,1例患儿复合杂合突变,Pt2-Pt5突变遗传自母亲,Pt6遗传自表型正常的父母。5例患儿均出现大脑皮层下白质弥漫性异常信号伴肿胀,1例患儿出现好转。结论GLIALCAM突变MLC患者多具有巨颅和典型头颅MRI表现,GLIALCAM突变显性遗传患者头颅MRI具有异质性,部分患儿头颅MRI可恢复正常。发现了c.275G>C(p.Arg92Pro)新突变,扩展了GLIALCAM突变谱,为准确的遗传咨询和产前诊断提供了依据。

胶质细胞病——伴皮层下囊肿的巨脑性脑白质病致病机制研究进展

伴皮层下囊肿的巨脑性脑白质病(MLC)是MLC1或GlialCAM突变导致的星形胶质细胞功能障碍的中枢神经系统髓鞘变性疾病,以星形胶质细胞肿胀与髓鞘囊泡形成为特征性病理改变。MLC/GlialCAM与ClC-2共定位于星形胶质细胞终足处,既往研究发现MLC1/GlialCAM突变后影响ClC-2通道的电容传导性,导致星形胶质细胞的水离子稳态失衡参与MLC的发病,但在GlialCAM纯合敲除的小鼠中,通过与选择性开放Clc-2通道的转基因小鼠杂交并不能纠正小鼠表型,提示有其他因素共同参与了MLC的发生发展。最近研究表明,突变后的MLC1通过促进Connexin43的内化,减少其在细胞膜处形成缝隙连接,影响细胞间通讯效率,从而导致水肿形成和髓鞘囊泡形成,进一步导致MLC的发生。这些研究提示,少突胶质细胞、星形胶质细胞及缝隙连接蛋白等构成的胶质细胞合胞体的功能异常是MLC致病机制的研究方向。

伴皮层下囊肿的巨脑性白质脑病患者新型冠状病毒感染的临床表现分析

目的总结伴皮层下囊肿的巨脑性白质脑病(MLC)患者新型冠状病毒感染的临床特点。方法通过调查问卷的方法收集并分析MLC患者新型冠状病毒感染的临床特点。结果30例MLC患者参与研究,男性18例,女性12例。患者年龄为3~20.67岁,中位年龄11.92岁。25例为经典型MLC,5例为改善型MLC。18例(60.00%)患者接种2针新型冠状病毒疫苗,且均无严重不良反应。21例(70.00%)患者感染新型冠状病毒,男性12例,女性9例。21例感染新型冠状病毒患者常见症状为发热(95.24%,20/21)和咳嗽咳痰(52.38%,11/21),嗜睡(9.52%,2/21)和抽搐(4.76%,1/21)较为少见,没有患者出现呼吸困难、运动倒退、昏迷。无患儿死亡。经典型与改善型患者在新型冠状病毒感染率和临床症状方面差异无统计学意义(P>0.05)。结论MLC患者感染新型冠状病毒的临床症状以发热及呼吸道症状为主,神经系统症状少见。

儿童伴皮层下囊肿的巨脑性脑白质病的MRI影像分析

目的伴皮层下囊肿的巨脑性脑白质病(MLC)又称van der Knaap病,是一种罕见的染色体遗传病。探讨MLC的临床及磁共振表现,以提高对该病的认识。方法搜集9例经临床基因确诊的MLC患儿,所有患儿均行高场头颅MRI平扫检查,回顾性分析其临床及MRI表现。结果本组9例患儿,男6例,女3例,年龄1个月~10岁,中位年龄14个月,2岁以下患儿6例。所有患儿均可见头围增大及不同程度发育迟缓,头颅MRI均表现为脑白质弥漫性肿胀,双侧颞叶皮层下囊肿、灰质不受累。其中4例累及双侧小脑半球,4例内囊后肢受累,4例外囊受累,3例皮质脊髓束受累,2例可见内囊前肢受累,4例胼胝体受累。3例伴有侧脑室增宽。3例行头颅DWI检查,受累部位DWI呈低信号,ADC值升高。结论MLC的临床及典型MRI表现能为该病的诊断提供有力证据,内囊前肢及胼胝体亦可受累。

伴皮层下囊肿的巨脑性白质脑病一家系MLC1基因突变分析

收集伴皮层下囊肿的巨脑性白质脑病(MLC)先证者及其父母的临床资料,采用聚合酶链反应和DNA直接测序法进行MLC1基因突变检测。患儿临床表现为运动发育迟缓、巨颅,头颅MRI扫描显示弥漫性脑白质肿胀,伴双侧额顶部皮层下囊肿。基因测序结果发现患儿携带MLC1基因2个杂合突变:第3外显子的错义突变c.217G>A(p.Gly73Arg)和第9内含子的剪接位点突变c.772-1G>C in IVS9-1。患儿的父母均为c.772-1G>C in IVS9-1杂合突变携带者,无临床症状。可推测患儿c.772-1G>C in IVS9-1突变来源于父母;c.217G>A(p.Gly73Arg)为新生突变,为国内外首次报道。

一个巨脑性白质脑病伴皮层下囊肿家系的遗传分析及产前诊断

目的对1个巨脑性白质脑病伴皮层下囊肿（megalencephalicleukoencephalopathywithsubcorticalcysts，MI。c）家系进行遗传分析并对高危胎儿进行产前诊断。方法应用PCR扩增MLCl基因的12个外显子及侧翼序列，对产物直接进行测序以寻找致病基因突变。选取1个短串联重复序列位点作为连锁分析遗传标记，结合DNA测序对胎儿进行产前诊断。结果家系中患者MLCj基因检测到1个缺失突变C．177_178delG（P．Ser60AlafsX5）和一个剪切位点突变C．598—2A〉C，后者为一种新突变，国际上尚未见报道。胎儿继承了父源性C－77—178delG突变，但未继承母源性C．598—2A〉C突变，与家系内1名表型正常的成员基因型一致。连锁分析结果与基因突变检测结果相符合。胎儿出生后表型正常，重新取材检测与产前诊断结果一致。结论发现了1种新的MLCI基因突变，为国内首次针对MLC家系开展的基因诊断，对于同类病例的遗传咨询、基因诊断和产前诊断具有借鉴意义。

巨脑性白质脑病伴皮质下囊肿一家系临床特征及基因突变分析

目的 分析巨脑性白质脑病伴皮质下囊肿（MCL）的临床特点及基因变异情况,探讨其遗传特点,为家庭提供遗传咨询.方法 收集患儿及其家系成员的临床资料,提取患儿及家系成员外周血DNA,采用目标序列捕获高通量测序技术和Sanger测序技术进行MLC1基因变异检测.结果 1.临床特点：婴儿期头围异常增大为首发症状;运动发育落后,并于学龄前期运动能力倒退,运动障碍逐渐进展,最终瘫痪;幼儿期出现癫痫;病程早期头颅磁共振成像显示双侧大脑半球白质弥散异常信号,伴颞叶囊性变,随病程进展出现脑萎缩.2.基因分析结果：先证者及胞姐的MLC1基因同时存在c.368C〉T（p.Thr123Ile）与c.353C〉T（p.Thr118Met）复合杂合变异;先证者之父及胞姐携带c.368C〉T（p.Thr123Ile）、患儿母亲携带c.353C〉T（p.Thr118Met）杂合变异,均为临床表型正常的携带者.结论 MCL是婴幼儿运动发育落后的病因之一,常以头围增大为首发症状.MLC1基因c.368C〉T（p.Thr123Ile）变异为MLC致病突变,且可能是本病又一个新突变.

两个伴皮层下囊肿的巨脑性白质脑病家系的产前诊断

目的对2个基因诊断明确的伴皮层下囊肿的巨脑性白质脑病（megalencephalicleukoencephalopathywithsubcorticalcysts，MLC）家系进行遗传咨询和产前分子诊断。方法先证者1和2分别于2011年6月和2009年6月在北京大学第一医院儿科就诊，采集先证者及其父母外周静脉血提取基因组DNA，采用DNA测序技术进行MLCl基因检测。先证者之母再次妊娠后，分别通过羊膜腔穿刺（孕21周“，胎儿1）和绒毛穿刺（孕12周”，胎儿2）采集羊水及绒毛标本。提取胎儿基因组DNA，应用DNA直接测序技术检测胎儿是否具有与先证者一致的MLCl基因突变类型，并通过聚合酶链反应技术扩增Y染色体性别决定区以及X染色体微卫星标记（AR、DXS6807和DXS6797）进行单体型分析判断胎儿羊水／绒毛中是否有母体细胞污染。胎儿出生后进行验证及电话随访。结果先证者1和2具有大头、运动发育落后及典型MLC头颅MRI表现，符合MLC的临床诊断。先证者lMLCl基因检出c．353C〉T（p．T118M）、c．803C〉G（p．T268R）复合杂合突变；先证者2检出c．353C〉T（p．T118M）和c．836T〉C（p．L279P）复合杂合突变。均基因确诊MLC。胎儿lMLCl基因相应位点发现c．803C（野生型）和c．353C〉T（p．Tl18M）杂合改变；胎儿2相应位点均为野生型（c．353C和c．836T）。且胎儿基因组DNA均无母体细胞污染。胎儿1生后基因验证结果与产前诊断结果一致，5月龄时头围及生长发育均正常；胎儿2现生后1个月，无巨颅，尚未进行生后验证。结论检测胎儿基因组DNA是否具有与先证者相同的MLCl基因突变类型，可对基因诊断明确的MLC家庭提供准确的产前分子诊断。通过Y染色体性别决定区及3个x染色体微卫星标记进行单体型分析可有效判断胎儿基因组中是否存在母体细胞污染，有助于排除母体细胞污染对产前诊断结果的影响，保证产前诊断结果的可靠性。

伴皮质下囊肿的巨脑性白质脑病

伴皮质下囊肿的巨脑性白质脑病（megalencephalic leukoencephalopathy with subcortical cysts．MLC）是一种常染色体隐性遗传疾病。1995年荷兰儿科医生van der Knaap等最先报道此病，故又称为van der Knaap病，2000年Tonpcu等将此病的相关基因定位于22q13．33，

伴皮质下囊肿的巨脑性白质脑病中年病例临床分析

MLC1基因突变导致的伴皮质下囊肿的巨脑性白质脑病(MLC)(OMIN:604004)是一种罕见的常染色体隐性遗传病。多于婴幼儿期起病,成人病例临床特点报道少见。国内仅报道过成人病例1家系2例患者。现报道1例58岁女性MLC患者,临床表现为头围大,反应迟钝,行走困难,发作性意识丧失。全外显子组测序发现MLC1基因c.920_943dup纯合重复突变,并进行了Sanger测序法的验证。本例患者的变异位点在人类基因突变数据库中未有报道。