The use of muscle biopsy in the diagnosis of undefined ataxia with cerebellar atrophy in children

Childhood cerebellar ataxias, and particularly congenital ataxias, are heterogeneous disorders and several remain undefined. We performed a muscle biopsy in patients with congenital ataxia and children with later onset undefined ataxia having neuroimaging evidence of cerebellar atrophy. Significant reduced levels of Coenzyme Q10 (COQ10) were found in the skeletal muscle of 9 out of 34 patients that were consecutively screened. A mutation in the ADCK3/Coq8 gene (R347X) was identified in a female patient with ataxia, seizures and markedly reduced COQ10 levels. In a 2.5-years-old male patient with non syndromic congenital ataxia and autophagic vacuoles in the muscle biopsy we identified a homozygous nonsense mutation R111X mutation in SIL1 gene, leading to early diagnosis of Marinesco-Sjogren syndrome. We think that muscle biopsy is a valuable procedure to improve diagnostic assesement in children with congenital ataxia or other undefined forms of later onset childhood ataxia associated to cerebellar atrophy at MRI.     

儿童铁粒幼红细胞贫血的临床特征及基因突变谱分析

目的 对铁粒幼红细胞贫血（SA）患儿的临床特征和基因突变谱进行分析，探讨目的基因捕获二代测序技术在SA患儿分子诊断中的临床应用价值，提高对SA的早期诊断和临床干预水平。方法 收集36例诊断为SA患儿的临床资料，采用目的基因捕获二代测序方法进行SA相关致病基因、与血红素合成及线粒体铁代谢有关的基因检测，分析基因型与临床表型的关系。结果 36例患儿中，32例为遗传性铁粒幼红细胞贫血（CSA），4例为骨髓增生异常综合征伴环形铁粒幼红细胞（MDS-RS）。共53%（19/36）患儿检测到CSA相关基因突变，其中ALAS2基因突变占47%（9/19），SLC25A38基因突变占21%（4/19），线粒体片段缺失占32%（6/19）。所有MDS-RS患儿均未检测到致病/可能致病性基因突变。89%（17/19）为已知致病突变，11%（2/19）为新变异。ALAS2基因新变异c.1153A > T （p.I385F）评级为"可能致病的"及SLC25A38基因新变异c.175C > T （p.Q59X）评级为"致病的"。结论 儿童CSA以ALAS2及SLC25A38基因突变为主，但线粒体基因片段缺失亦占有相当比例，对于婴儿期即出现的低增生性贫血，需考虑线粒体病的可能。     

广西地区β-地中海贫血的基因型与临床型的关系

我们分析４９例无亲缘关系的β－地中海贫血双重杂合子或纯合子的基因突变类型和临床表现。检出１０种突变类型，发现５例复合东南亚缺失型α－地中海贫血、６例复合Ｇｙ启动予－１５８ｎｔ（Ｃ→Ｔ）突变。根据这些患者的血红蛋白量，可将他们分成轻、中、重度贫血。２例β＋纯合子表现为轻度贫血；５例复合东南亚缺失型α－地中海贫血，６例复合Ｇｙ启动子－１５８ｎｔ（Ｃ→Ｔ）的患者均表现为中度贫血。这三种类型临床上表现为中间型β－地中海贫血，大多数单纯的Ｂ１与Ｂ０双重杂合子和β０纯合子表现为重型β－地中海贫血。     

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。     

Pathophysiology and genetic mutations in congenital sideroblastic anemia

Sideroblastic anemias are heterogeneous congenital and acquired disorders characterized by anemia and the presence of ringed sideroblasts in the bone marrow. Congenital sideroblastic anemia (CSA) is a rare disease caused by mutations of genes involved in heme biosynthesis, iron–sulfur [Fe‐S] cluster biosynthesis, and mitochondrial protein synthesis. The most common form is X‐linked sideroblastic anemia, due to mutations in the erythroid‐specific δ‐aminolevulinate synthase (ALAS2), which is the first enzyme of the heme biosynthesis pathway in erythroid cells. Other known etiologies include mutations in the erythroid specific mitochondrial transporter (SLC25A38), adenosine triphosphate (ATP) binding cassette B7 (ABCB7), glutaredoxin 5 (GLRX5), thiamine transporter SLC19A2, the RNA‐modifying enzyme pseudouridine synthase (PUS1), and mitochondrial tyrosyl‐tRNA synthase (YARS2), as well as mitochondrial DNA deletions. Due to its rarity, however, there have been few systematic pathophysiological and genetic investigations focusing on sideroblastic anemia. Therefore, a nationwide survey of sideroblastic anemia was conducted in Japan to investigate the epidemiology and pathogenesis of this disease. This review will cover the findings of this recent survey and summarize the current understanding of the pathophysiology and genetic mutations involved in CSA.     

Ataxia with isolated vitamin E deficiency: a clinical, biochemical and genetic diagnosis

A case of ataxia with isolated vitamin E deficiency, in conjunction with supportive genetic studies, is reported. This is a neurodegenerative condition that involves a mutation in the tocopherol (alpha) transfer protein gene (TTPA). Measurement of serum vitamin E concentration should be included as part of the investigations in children with progressive ataxia, even in the absence of fat malabsorption. Early treatment with vitamin E may protect such patients against further neurological damage.     

Lessons from fragile X regarding neurobiology, autism, and neurodegeneration

The fragile X mental retardation 1 gene (FMR1) mutation causes two disorders: fragile X syndrome (FXS) in those with the full mutation and the fragile X-associated tremor/ataxia syndrome (FXTAS) in some older individuals with the premutation. FXS is caused by a deficiency of the FMR1 protein (FMRP) leading to dysregulation of many genes that create a phenotype with ADHD, anxiety, and autism. FXTAS is caused by the elevation of FMR1-mRNA to levels 2 to 8 times normal in the premutation. This causes an RNA gain of function toxicity leading to brain atrophy, white matter disease, neuronal and astrocytic inclusion formation, and subsequent ataxia, intention tremor, peripheral neuropathy, and cognitive decline. The neurobiology and pathophysiology of FXS and FXTAS are described in detail.     

Nijmegen breakage syndrome: clinical characteristics and mutation analysis in eight unrelated Russian families

OBJECTIVE: The purpose of the study was to ascertain patients with Nijmegen breakage syndrome (NBS) in the Russian population and characterize the clinical phenotype and molecular genotype of these patients. STUDY DESIGN: Eight unrelated Russian patients with possible diagnoses of NBS were identified. Family histories were collected and clinical and laboratory analyses were carried out. Mutation screening of the NBS1 gene was carried out to confirm the diagnosis in 7 cases. RESULTS: All patients had the key diagnostic features of NBS. One patient had acute myeloblastic leukemia (AML). Two patients had bone marrow aplasia, not previously described as a feature of NBS. Mutation screening of the NBS1 gene revealed that 6 patients were homozygous for the 657del5 mutation, whereas a seventh patient was a compound heterozygote, having the 657del5 mutation and an additional novel mutation, 681delT. CONCLUSIONS: Molecular analyses confirmed the diagnosis of NBS in 7 of the patients. The surprising finding of bone marrow aplasia or AML in 3 of 7 patients raises the possibility of a connection between NBS and another DNA damage disorder, Fanconi anemia.     

先天性纯红细胞再生障碍性贫血的临床及基因特点

目的探讨先天性纯红细胞再生障碍性贫血(DBA)的临床及致病基因特点。方法回顾性分析2例DBA患儿的临床及致病基因特点,并进行文献复习。结果 2例患者(2~3个月的婴儿)均呈慢性重度正细胞正色素贫血,不伴白细胞及血小板计数异常,网织红细胞计数均降低,血清铁、血清铁蛋白轻度升高,骨髓细胞学提示红细胞比例明显降低、幼红减少或缺如,1例DBA致病基因检测发现已报道的RPS19基因致病性杂合突变:c.212GA(p.Gly71Glu),其父母未见突变;另1患儿检测到新的RPL5基因杂合突变:c.740TC(p.I247L),其父母未见突变,生物信息学分析该突变可能致病。结论 DBA患儿多在婴儿早期发病,以红系缺乏为表现,编码核糖体亚基蛋白的基因突变为常见病因,进行分子检测有利于DBA早期诊断。     

首例非白人婴儿肝衰竭综合征1型患儿临床特点和分子诊断研究

婴儿肝衰竭综合征1型(ILFS1)是一种由胞质亮氨酰-t RNA合成酶基因(LARS)突变所导致的常染色体隐性遗传病。本研究报道首例非白人ILFS1患者的临床特点和分子诊断经过,为ILFS1的诊治提供参考。患者为2岁9个月男孩,因发现肝脾肿大1年余就诊。1岁5个月时发现肝脾大,实验室检查发现丙氨酸氨基转移酶和门冬氨酸氨基转移酶偏高、低蛋白血症、凝血功能异常和贫血,肝脏病理提示肝硬化和脂肪肝;SLC25A13基因高频突变筛查和一代测序分析仅检测到一个父源性突变c.1658GA,cDNA克隆分析也未发现母源性SLC25A13等位基因异常转录子;代谢性肝病相关基因外显子组捕获二代测序在患儿LARS基因检出父源性突变c.2133_2135del(p.L712del)和母源性突变c.1183GA(p.D395N),经一代测序验证,最终确诊为ILFS1。目前随访至4岁,肝功能正常,无贫血,仍有低蛋白血症。     

A novel aspartoacylase (ASPA) gene mutation in Canavan disease

Canavan disease is a severe autosomal recessive leukodystrophy characterized by macrocephaly, ataxia, severe motor and mental retardation, dysmyelination, and progressive spongial atrophy of the brain. The human aspartoacylase (ASPA) gene, which catalyzes the deacetylation of N-acetyl-L-aspartate, is mutated in Canavan disease. In the presented family sequencing analysis for the aspartoacylase gene was performed on the blood samples of the parents as the affected child had died due to Canavan disease. After the mutation was detected, prenatal diagnosis was also performed and heterozygous Y88X mutation was detected in the fetus. In this report, we present a novel mutation Y88X within the aspartoacylase gene in a consanguineous family with an affected child diagnosed as Canavan disease.     

3例赖氨酸尿性蛋白耐受不良患儿的临床特点及SLC7A7基因突变分析

赖氨酸尿性蛋白耐受不良（LPI）是由SLC7A7基因突变引起的一种常染色体隐性遗传病,常常累及多个系统病变,肺部受累较为常见,儿童患者预后差。该文总结3例经SLC7A7基因分析确诊为LPI患儿的临床表现和基因突变特点。3例患儿均表现为断乳后不喜蛋白饮食、生长发育落后、贫血、肝脾肿大、骨质疏松等,均有尿乳清酸增高。2例表现有间质性肺炎、弥漫性肺间质病变。SLC7A7基因检测结果显示3例患儿中共检测出3种致病突变：c.1387delG（p.V463CfsX56）、c.1215G > A（p.W405X）和纯合c.625+1G > A。3例患儿诊断明确后,予低蛋白饮食,口服瓜氨酸100 mg/（kg·d）、蛋白琥珀酸铁4 mg/（kg·d）、葡萄糖酸钙锌10 mL/d、维生素D 400 IU/d,例3还予醋酸泼尼松5 mg/d治疗,症状和体征均有不同程度改善。LPI的氨基酸和有机酸代谢特点与尿素循环障碍较难鉴别,SLC7A7基因分析是LPI确诊的依据。     

Autosomal dominant transmission of congenital hypothyroidism, neonatal respiratory distress, and ataxia caused by a mutation of NKX2-1

OBJECTIVE: To study the NKX2-1 gene in two half-siblings with elevated thyroid-stimulating hormone (TSH) on state screen, prolonged neonatal respiratory distress despite term gestations, and persistent ataxia, dysarthria, and developmental delay. STUDY DESIGN: We amplified and sequenced DNA samples from blood or buccal swab for subjects and their unaffected siblings. RESULTS: The same mutation that prevents splicing together of exons 2 and 3 of the NKX2-1 gene was present in the affected siblings, their mother, and maternal grandmother but not in their unaffected siblings. The mutation was present in the heterozygous form, thus explaining the disease phenotype. CONCLUSIONS: Autosomal dominant transmission of mutations of NKX2-1 may cause congenital hypothyroidism, neonatal respiratory distress at term, and persistent neurologic findings such as ataxia, choreoathetosis, and dysarthria in families with affected subjects in multiple generations.     

AHDC1基因突变致Xia-Gibbs综合征1例报告并文献复习

目的：探讨 AHDC1基因突变致Xia-Gibbs综合征的临床特征及基因变异特点。方法：回顾性分析1例 AHDC1基因突变致Xia-Gibbs综合征患儿的临床资料和全外显子组测序（WES）结果,并行系统检索和文献复习,收集基因诊断明确的 Xia-Gibbs综合征患者,总结临床表现和基因突变信息。 结果男,15月龄,因“发育落后”就诊。就诊时不会说话,不会爬;耳位低,左眼内斜视;双侧肌张力降低。心脏超声示卵圆孔未闭,肾脏B超示双侧肾盂积水;颅脑MRI示脑白质减少,胼胝体薄;脑电图示双侧高幅δ波及θ波,两前部明显。WES发现 AHDC1基因新发剪切突变c.750_753delCCTC, 导致蛋白编码提前终止（p.T252Afs*7）。文献复习共检索到6篇英文文献,与本文病例合并后共报告15例 AHDC1突变患儿,均有发育落后、面部畸形、肌张力低下、上呼吸道梗阻和睡眠障碍,共济失调、癫、孤独症、喂养障碍和视力障碍等也较常见,颅脑影像学胼胝体发育不良常见;已报道13个突变位点,剪切突变最常见。结论：AHDC1基因突变致Xia-Gibbs综合征的主要特点为发育落后、面部畸形、肌张力低下和睡眠障碍等,卵圆孔未闭和肾盂积水的表型是否与 AHDC1基因突变相关,有待进一步证实。     

Severe hepatic Wilson's disease in preschool-aged children

A 3-year-old girl presented with hemolytic anemia, hepatosplenomegaly, ascites, and evidence of decompensated chronic liver disease. Genotypic DNA analysis revealed that the patient was homozygous for a splice site mutation now designated IVS4-1:G>C, expected to destroy completely the functional gene product of ATP7B, the gene responsible for Wilson's disease. We suggest that this severe mutation caused very early liver disease. Wilson's disease should be considered in the differential diagnosis of established liver disease in the preschool-aged child.     

Transaldolase deficiency: a new cause of hydrops fetalis and neonatal multi-organ disease

Transaldolase (TALDO) deficiency is a newly recognized metabolic disease, which has been reported so far in 2 patients presenting with liver failure and cirrhosis. We report a new sibship of 4 infants born to the same consanguineous parents; all presented at birth or in the antenatal period with dysmorphic features, cutis laxa and hypertrichosis, hepatomegaly, splenomegaly, liver failure, hemolytic anemia, thrombocytopenia, and genitourinary malformations. The clinical courses were variable: the first child died of liver failure at 4 months of age; the second pregnancy was medically terminated at 28 weeks gestation because of hydrops fetalis with oligohydramnios. The third child is doing well at age 7 with liver fibrosis and mild kidney failure. The fourth child is now 21 months old and has hepatosplenomegaly, mild anemia, and thrombocytopenia. Urine assessment of polyols showed elevations of erythritol, arabitol, and ribitol consistent with TALDO deficiency. TALDO activity was undetectable in the patients' tissues, and mutation in the TALDO1 gene was found in the 4 patients.     

Incomplete hemolytic uremic syndrome associated with partial factor H deficiency

Hemolytic uremic syndrome (HUS) consists of the association of hemolytic anemia, thrombocytopenia and renal failure. Most cases are related to toxins (verotoxins) produced by Escherichia coli 0157:H7 and generally have good renal prognosis. Atypical forms can occur, with a less favorable prognosis, and can be due to mutations in the gene codifying factor H, a protein that regulates activation of the alternative complement pathway, among other causes. Factor H deficiency produces continuous complement activation, causing injury to capillary endothelial cells. We report a case of incomplete (absence of thrombocytopenia and uremia), atypical HUS in which hypocomplementemia secondary to partial factor H deficiency was detected, with favorable outcome. Prior to symptom onset, the patient had a Campylobacter infection, precipitating the symptoms. Genetic analysis showed a heterozygous mutation (C846T) located in the SCR4 domain, generating an amino acid change in the factor H molecule (Pro240Leu). This mutation may have been the cause of the partial factor H deficiency and the patient's symptoms on admission.     

一个伴脊髓与脑干受累以及脑白质乳酸升高的脑白质病家系临床及DARS2基因突变分析

目的 探讨一个伴脊髓、脑干受累,脑白质乳酸升高的脑白质病(LBSL)家系的临床和影像学特点,并检测其致病基因DARS2的突变情况.方法 收集并分析先证者的临床资料,应用PCR方法对DARS2基因的所有17个外显子及其外显子内含子连接区域进行扩增,采用DNA直接测序与DNA限制性内切酶酶切、100条正常染色体对照验证的方法进行DARS2基因突变检测.结果 (1)临床特点:先证者发病年龄为14岁,以运动倒退、走路姿势异常起病,下肢运动障碍重于上肢,智力基本正常,头颅核磁及磁共振波谱(MRS)符合LBSL特点.(2)基因突变分析:先证者DARS2基因发现第8外显子c.665 G＞A(p.Gly222Asp)与第2内含子c.228-16 C＞G,首次证实了我国LBSL患者中存在DARS2基因突变.家系突变分离研究结果表明,c.665 G＞A(p.Gly222Asp)来自其父亲,c.228-16 C＞G突变则来源于其母亲,其兄携带c.228-16 C＞G,父母及其兄均为表型正常的携带者,符合常染色体隐性遗传规律.结论 在国内诊断第1例LBSL病,明确了该家系中的致病基因突变及相关个体基因状况,为该家庭进行准确的遗传咨询提供了可能.     

Reduced gene expression of clustered ribosomal proteins in Diamond-Blackfan anemia patients without RPS19 gene mutations

Diamond-Blackfan anemia (DBA) is a rare congenital pure red cell aplasia occasionally presenting physical anomalies. Ribosomal protein S19 gene (RPS19) is one of the causative genes for DBA; however, the pathologic mechanism of erythroblastopenia and abnormal morphology has not been clarified. To assess the pathophysiology of DBA, the gene expression profile of 2 representative patients carrying no RPS19 mutations was compared with that of aplastic anemia (AA) patients, assessed by the microarray analyses. The K-mean clustering analysis revealed the significant categorization of 28 ribosomal protein (RP) genes into a small set of group (994 genes) (P=2.39E-17), all of which were expressed at lower levels in DBA than in AA patients. RPS19 was categorized into the set of low expressing genes in DBA patients. No mutations were determined in the promoter and coding sequences of top 10 RP genes expressed at the levels over 1.2 of the AA/DBA ratio, in 3 DBA patients. These results indicated that the lower expression of RP gene group, even without the mutation, was a distinctive feature of DBA from AA, although the study number was small. The reduced RP gene expression, by itself, may suggest an underlying mechanism of the constitutional anemia.