Use of targeted next‐generation sequencing for molecular diagnosis of craniosynostosis: Identification of a novel de novo mutation of EFNB1

Craniofrontonasal syndrome (CFNS; MIM#304110) is characterized by asymmetric facial features with hypertelorism and a broad bifid nose due to synostosis of the coronal suture. CFNS shows a unique X‐linked inheritance pattern (most affected patients are female and obligate male carriers exhibit a mild manifestation or no typical features at all) associated with the ephrin‐B1 gene (EFNB1) located in the Xq13.1 region. In this study, we performed targeted, massively parallel sequencing using a next‐generation sequencer, and identified a novel EFNB1 mutation, c.270_271delCA, in a Japanese female patient with craniosynostosis. Because subsequent Sanger sequencing identified no mutation in either parent, this mutation was determined to be de novo in origin. After obtaining molecular diagnosis, a retrospective clinical evaluation confirmed the clinical diagnosis of CFNS in this patient. Comprehensive molecular diagnosis using a next‐generation sequencer would be beneficial for early diagnosis of the patients with undiagnosed craniosynostosis.     

EFNB1 mutation at the ephrin ligand-receptor dimerization interface in a patient with craniofrontonasal syndrome

Craniofrontonasal syndrome (CFNS) is characterized by craniosynostosis, hypertelorism, a broad nasal tip and occasionally cleft lip and palate, and is caused by a mutation in the ephrin-B1 gene (EFNB1). The study of naturally occurring human EFNB1 mutations offers a unique opportunity to better define the critical portion within the ephrin domain that is essential for the function of EFNB1 protein in craniofacial development. Here, we report a CFNS patient with a novel EFNB1 missense mutation present at the interface between EFNB1 and its receptor proteins. The patient's facial features included hypertelorism, a broad nasal tip, brachycephaly, frontal bossing, facial asymmetry and esotropia. In addition, she had pectus carinatum, grooved nails on her thumb, an abnormal palmar crease pattern and a broad first toe. Her development was appropriate for her age. Direct sequencing of polymerase chain reaction products using an autosequencer revealed a heterozygous missense mutation, Ser118Ile. Ser118 is located in the G-H loop of the extracellular ephrin domain and is highly evolutionarily conserved among rodents, avians and fish. The mutation occurred de novo and was not present in 100 normal Japanese control subjects. Substitutions of the adjacent amino acid residue, Pro119, have been previously reported in three CFNS patients. Since the structure of EFNB1 is not yet available, the spatial locality of Ser118 was characterized using the protein structure of EFNB2. We deduced that Ser118 in EFNB1 resides at the major dimerization interface with Eph receptors and inferred that the Ser118Ile mutation may impede the protrusion of the G-H loop, thereby disturbing Eph-Ephrin signal transduction.     

Genetic Analysis in Bartter Syndrome from India

Bartter syndrome is a group of inherited, salt-losing tubulopathies presenting as hypokalemic metabolic alkalosis with normotensive hyperreninemia and hyperaldosteronism. Around 150 cases have been reported in literature till now. Mutations leading to salt losing tubulopathies are not routinely tested in Indian population. The authors have done the genetic analysis for the first time in the Bartter syndrome on two cases from India. First case was antenatal Bartter syndrome presenting with massive polyuria and hyperkalemia. Mutational analysis revealed compound heterozygous mutations in KCNJ1(ROMK) gene [p(Leu220Phe), p(Thr191Pro)]. Second case had a phenotypic presentation of classical Bartter syndrome however, genetic analysis revealed only heterozygous novel mutation in SLC12A gene p(Ala232Thr). Bartter syndrome is a clinical diagnosis and genetic analysis is recommended for prognostication and genetic counseling.     

Epilepsy with a de novo missense mutation in the sodium channel a1 subunit: a case report

Most epilepsies are characterized as "idiopathic" because of the lack of a known cause. Nevertheless, recently, there has been significant progress in the molecular genetics of idiopathic epilepsy. Mutations in gene-encoding ion channels were found to be the underlying disorder in all idiopathic epilepsies with a known molecular basis. Missense mutations in the voltage-gated sodium channel a1 subunit gene (SCN1A) were firstly identified in patients with generalized epilepsy with febrile seizures plus additional symptoms (GEFS + ). Subsequently, mutations of SCN1A were also found in patients with severe myoclonic epilepsy of infancy (SMEI) or Dravet syndrome, and in patients with borderline SMEI (SMEB), a milder form of Dravet syndrome. We describe a case of a new missense de novo mutation of SCN1A in a child with the clinical features of borderline SMEI syndrome.     

Wolcott-Rallison syndrome: a clinical and genetic study of three children, novel mutation in EIF2AK3 and a review of the literature

Background: Wolcott-Rallison syndrome is a rare autosomal recessive condition characterized by early infancy onset diabetes mellitus and multiple epiphyseal dysplasia. So far, 17 children have been described in the world literature. Recently, mutations in the gene encoding EIF2AK3 have been shown to segregate with the syndrome in three affected families. Aims: We aimed to describe the clinical characterization and mutation analysis of a further child, and full clinical and follow-up details on our first family including the longest surviving child. Methods: Retrospective case notes review of three children presenting to the diabetic unit at our institution; mutation analysis of the EIF2AK3 gene in our most recent patient; and review of the literature on Wolcott-Rallison syndrome. Results: Previously unreported phenotypic features in our patients included developmental regression after episodes of hepatic failure, and pachygyria on brain imaging. We have identified a novel 4-base pair deletion (nt 3021-3024 del GAGA) in exon 13, which results in a frameshift and premature stop codon (R908 F/S +22X), causing premature truncation of the protein and abolition of the carboxy- segment of the catalytic domain.

Conclusions: Wolcott-Rallison syndrome causes early-onset diabetes and acute hepatic failure, before epiphyseal dysplasia is manifest. We have identified a novel mutation in EIF2AK3, and prenatal diagnosis may now be offered to affected families.     

Congenital central hypoventilation syndrome and Hirschsprung's disease in an extremely preterm infant

Congenital central hypoventilation syndrome with Hirschsprung's disease, also known as Haddad syndrome, is a rare disorder with a variable phenotypic severity. The underlying cause is thought to be an abnormality of neural crest development and/or migration. Surviving neonates can have generalized autonomic nervous system dysfunction. Recent reports have identified mutations in the PHOX2B gene in a significant number of patients with this disorder. Diagnosis and management of this disorder in the setting of extreme prematurity is difficult as the manifestations of failure to maintain breathing effort and failure to establish feeds overlap with the complications of prematurity. We describe an infant who had congenital central hypoventilation syndrome with Hirschsprung's disease and was delivered at 26 weeks' gestational age and had total aganglionosis of the bowel, failure to wean from ventilation, and a mutation in the PHOX2B gene.     

Sotos syndrome: a novel nonsense mutation in NSD1 gene, presenting with neonatal cutis laxa

Sotos syndrome is an overgrowth condition characterized by facial gestalt, macrocephaly, excessive height, and different degrees of developmental delay. We report the case of a 20-month-old boy with a confirmatory molecular study, showing a novel nonsense mutation in NSD1 gene, presenting cutis laxa as the main phenotypic trait in the neonatal period. This association has been previously described in 3 patients with a clinical diagnosis of Sotos syndrome, without confirmatory molecular analysis. Our patient was tested for congenital disorders of glycosilation as part of the cutis laxa differential diagnosis. During the postnatal follow-up period the head circumference and height became greater than 97(th) percentile (having been close to the 50(th) in the newborn period). These facts and the progressive development of characteristic phenotypic features of Sotos syndrome during the first months of life gave us the clue for the clinical diagnosis and the molecular investigation.     

PTEN基因新发变异致儿童Cowden综合征1例并文献复习北大核心CSCD

目的总结1例儿童Cowden综合征临床及基因突变特征并进行文献复习。方法回顾性分析2020年6月新乡医学院第一附属医院收治的1例Cowden综合征患儿临床资料,并以"Cowden综合征"、"PTEN基因"、"错构瘤息肉"、"儿童"、"Cowden syndrome and child"、"PTEN and child"为检索词,检索建库至2021年3月中文数据库(中国知网数据库、万方数据库)及PubMed数据库进行文献复习。结果患儿,男,13岁,间断腹痛、腹胀5个月就诊,儿童电子显微胃肠镜检查提示多发息肉,息肉组织活检见灶状淋巴细胞聚集浸润。全外显子测序发现患儿PTEN基因存在c.475(exon5)A>T杂合核苷酸变异,该变异导致第159号氨基酸由精氨酸变为色氨酸,通过蛋白三级结构预测发现该变异可能影响蛋白的空间结构,可能导致蛋白功能受到损害.结合患儿临床特点,确诊为Cowden综合征。家系验证变异遗传自母亲,母亲有类似表型。检索符合条件的中文文献0篇,与PTEN突变有关的41篇儿童病例报道的英文文献中,仅2篇报道与儿童Cowden综合征有关,该变异未见报道。结论本研究发现导致Cowden综合征的新的PTEN基因c.475(exon5)A>T突变位点,为国内首例儿童Cowden综合征病例报道。     

Allgrove syndrome with features of familial dysautonomia: a novel mutation in the AAAS gene

Allgrove syndrome (or triple-A syndrome) is a rare autosomal recessive disorder characterized by alacrima, achalasia, adrenal insufficiency (glucocorticoid in the majority of cases) and autonomic/neurological abnormalities. This disease is now known to be caused by mutation in the AAAS gene located on chromosome 12q13. Diagnosis should be readily available when the full-blown features are there, but it becomes less apparent when presentation is atypical or in the evolving process. We present a brother and sister (12 and 19 y old, respectively) born to consanguineous parents of Palestinian origin with Allgrove syndrome. The index patient was erroneously diagnosed to be a case of familial dysautonomia before the diagnosis of adrenal insufficiency was made at the age of 7.5 y, while his elder sister had only alacrima from birth and developed achalasia at the age of 15 y. She started to develop early evidence of adrenal disease at the age of 19 y. Both of them had neuroautonomic dysfunction. The diagnosis of Allgrove syndrome was confirmed in these two patients by studying the gene mutation in the family. The sequencing of the AAAS gene in the two patients identified a novel homozygous mutation within intron 5 (IVS5+1G-->A). Both parents as well as all three other children were heterozygous for the same mutation. CONCLUSION: These two cases illustrate the heterogenous nature and the intrafamilial phenotypic variability of Allgrove syndrome.     

Variable clinical phenotype in two siblings with Aicardi-Goutières syndrome type 6 and a novel mutation in the ADAR gene

Aicardi-Goutières syndrome (AGS) is a hereditary inflammatory encephalopathy resulting in severe neurological damage in the majority of cases. We report on two siblings with AGS6 due to compound heterozygosity for a known and a novel mutation in the ADAR gene and a strikingly variable phenotype. The first sibling presented at 12 months of age with a subacute encephalopathy following a mild respiratory infection. The child developed a spastic tetraparesis, generalized dystonia and dysarthria. In contrast, the younger sibling presented with an acute episode of neurological impairment in his third year of life, from which he recovered without sequelae within a few weeks. These findings illustrate a striking intrafamilial phenotypic variability in patients with AGS6 and describe the first case of a full recovery from an acute encephalopathy in an AGS patient. Our findings also suggest that AGS should be considered as an important differential diagnosis of an infection-triggered encephalopathy in infancy despite the absence of typical neuroimaging findings.     

CXCR4基因突变致WHIM综合征3例报告并文献复习

目的探讨CXCR4基因突变导致WHIM综合征的临床特征及基因变异特点。方法回顾性分析3例CXCR4基因突变致WHIM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,收集诊断明确的WHIM综合征患者,总结临床特征和基因突变信息。结果3例WHIM综合征患儿均为男性,确诊年龄分别为11岁、13月和5岁。3例均有反复感染,均无皮肤疣表现,1例发生糖尿病。3例患儿多次查血常规示淋巴细胞及中性粒细胞减少,但无周期性特征;3例患儿免疫球蛋白均减低。2例行骨髓穿刺检查,其中1例有典型无效生成性慢性粒细胞缺乏样表现。2例患儿经集落刺激因子治疗后,WBC可升至正常,但易反复。WES结果显示,3例患儿均为CXCR4基因第2外显子C端杂合突变,在该基因第2外显子剪切位点发生碱基替换突变（1000C>T）,造成氨基酸R334X改变。共检索到46篇WHIM综合征文献（45篇英文,1篇中文）,共报告WHIM患者74例（包括本文3例）。74例患者中,男32例,女42例,成人36例,儿童38例。出现皮肤疣的起病中位年龄为6.5岁;65例（87.8%）患者表现为反复感染;60例（81.1%）报告基因检测结果,共检测到9个突变,均为CXCR4基因突变。结论WHIM综合征为罕见的常染色体显性遗传病,可表现为粒细胞减少、低丙种球蛋白血症、疣状物、反复感染（尤其对人乳头状瘤病毒易感）及无效生成性慢性粒细胞缺乏。小年龄患儿可无皮肤疣,临床发现上述表现应考虑该病,并行基因检测以明确诊断。     

Alagille syndrome and aneurysmal subarachnoid hemorrhage. Case report and review of the literature

The authors report the case of a 21-year-old female with a known history of Alagille syndrome (AGS) who was found to have a basilar terminus aneurysm without evidence of rupture. Prior to intervention, the patient's hospital course became complicated by multiple medical problems associated with AGS. Subsequently, the patient had an acute neurological decline. An unenhanced CT of the head demonstrated diffuse subarachnoid hemorrhage, intraparenchymal hematoma and intraventricular hemorrhage. AGS is an autosomal dominant arteriodysplastic syndrome with multiple organ system involvement caused by a mutation in the Jagged1 gene. Intracranial hemorrhage is one of the many complications observed in this patient population. While there are multiple case reports in the literature reviewing the spectrum of cerebrovascular events and abnormalities, intracranial aneurysmal rupture has only recently been described. To our knowledge, this is the third reported case of documented aneurysmal subarachnoid hemorrhage in a patient with AGS. The authors present a brief review of the vascular abnormalities both intracranial and systemic seen in AGS. The genomic abnormalities of this syndrome are also reviewed with particular attention to the Jagged1 gene and the Notch receptor signaling pathway which may reveal elements of the pathophysiology involved in aneurysm formation and rupture in AGS patients. In light of the increased incidence of intracranial hemorrhage in AGS and the possible link to aneurysmal subarachnoid hemorrhage, establishing the incidence of intracranial aneurysms in AGS and the role of screening these patients is indicated.     

Medium-chain acyl-CoA dehydrogenase deficiency: Molecular aspects

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is an autosomal recessive disorder which is known to cause Reye-like syndrome in children and sudden infant death. A point mutation of lysine329-to-glutamic acid329 substitution in the MCAD gene was recently identified as the most common mutation in patients with MCAD deficiency. This mutation is responsible for about 90% of mutant MCAD alleles in Caucasians. Patients with this type of mutation have a variety of symptoms, indicating that the clinical heterogeneity of MCAD deficiency may not be caused entirely by genetic heterogeneity. Screening for the mutation among newborns in England, Australia, and United States of America indicates the prevalence of carriers to be 1 in 40-107, suggesting the high incidence of the mutation. Since presymptomatic diagnosis and appropriate dietary management are important in MCAD deficiency to prevent life-threatening complications, the relatively high incidence of this disorder may warrant population screening. The most common MCAD mutation can now be detected by DNA diagnostic methods using Guthrie cards. This makes it possible to screen a population efficiently for this potentially fatal disorder.     

Novel missense mutation of the UGT1A1 gene in Thai siblings with Gilbert''s syndrome

BACKGROUND: Gilbert's syndrome is a common inherited disorder of bilirubin metabolism contributing to the development of neonatal jaundice and causing recurrent jaundice after the neonatal period. In the patients with Gilbert's syndrome, mutations have been reported in the promoter and exons of the uridine diphosphate-glucuronosyl transferase 1 (UGT1A1) gene on chromsome 2q37, which encodes bilirubin uridine diphosphate-glucuronosyltransferase. However, the genetic basis of Gilbert's syndrome, including its inheritance trait, remains to be clarified. METHODS: Patients 1 and 2 were Thai sisters with Gilbert's syndrome. They had a history of prolonged neonatal jaundice and showed recurrent jaundice after their infancy, while the parents showed no symptoms. To search for the mutation in the patients, all exons of the UGT1A1 gene were amplified by polymerase chain reaction (PCR) and sequenced directly. The frequency of the mutation in controls was studied by PCR-restriction enzyme digestion method. RESULTS: The patients were homozygous for a novel single transition of T to C at nucleotide position 247 (exon 1), which would predict a substitution of leucine for phenylalanine at codon 83 of the enzyme protein. No other mutation was detected in any regions except exon 1. The parents with no symptoms showed heterozygosity for the mutation. Among the 110 Japanese controls, no homozygous individuals and three heterozygous individuals for the mutation were identified, giving a mutated allele frequency of 0.0136. CONCLUSIONS: A novel missense mutation in the UGT1A1 gene was identified in two Thai siblings with Gilbert's syndrome. The affected family showed that homozygosity for the mutation may lead to apparent symptoms and that the syndrome was inherited as an autosomal recessive trait. The mutation does not explain a high incidence of neonatal jaundice in Japan, because it is very rare in the Japanese population.     

KMT2D基因致病变异致Kabuki综合征新生儿14例病例系列报告并文献复习

背景 Kabuki综合征(KS)是一种罕见的多发畸形综合征,主要临床表现为特殊面容、骨骼异常、智力障碍等.KMT2D基因致病变异所致KS占75％.目前KS诊断标准用于新生儿期诊断较为困难.目的 提出KMT2D基因突变所致KS在新生儿期的遗传筛查指征.设计病例系列报告.方法 回顾性分析复旦大学附属儿科医院(我院)KMT2...     

KCNQ1OT1 hypomethylation: A Novel disguised genetic predisposition in sporadic pediatric adrenocortical tumors?

Pediatric adrenal tumors, other than neuroblastoma, are rare and can be associated with a genetic predisposition. In this report we describe two patients with an isolated and apparently sporadic adrenocortical tumor; one girl with a carcinoma, the other girl with an adenoma. In both patients genetic screening revealed hypomethylation of the KCNQ1OT1 gene, well-known for its association with the Beckwith-Wiedemann syndrome. This represents a likely novel genetic predisposition in patients with adrenocortical tumors without clear phenotypic features of the Beckwith-Wiedemann syndrome.     

X-linked hyper IgM syndrome: a novel sequence variant associated with an atypical mild phenotype

X-linked hyper IgM syndrome is associated with abnormalities in the gene encoding CD40 ligand (CD40LG). A typical phenotype evolves during infancy in affected males. This phenotype includes neutropenia, dysgammaglobulinemia, bacterial sinopulmonary infections, and opportunistic infections. In the absence of the typical phenotypic features, clinicians must maintain a high level of suspicion for X-linked hyper IgM syndrome. We describe a unique hemizygous CD40LG mutation which was discovered in a 12-year-old boy with chronic severe neutropenia, a normal IgG level, and absence of sinopulmonary or opportunistic infections. The clinical implications of this mutation and associated atypical phenotype are discussed.     

Noonan syndrome caused by germline <Emphasis Type="Italic">KRAS</Emphasis> mutation in Taiwan: report of two patients and a review of the literature

Noonan syndrome is a highly variable disorder that has significant phenotypic overlap with Costello syndrome and cardio-facio-cutaneous syndrome. KRAS mutation was the second reported gene for Noonan syndrome. This study screened for mutation of the KRAS gene in 57 unrelated ethnic Chinese children suffering from Noonan syndrome without PTPN11 gene mutation in Taiwan. This work only identified two patients with different missense mutations (c.40G>A, p.Val14Ile; c.108A>G, p.Ile36Met) in the exon 1 of KRAS gene. This study also analyzed the characteristics of 34 reported cases involving KRAS mutations in the literature. All these patients presented with variable phenotypes, including Noonan syndrome (n = 19), cardio-facio-cutaneous syndrome (n = 7), Costello syndrome (n = 6), and Noonan/cardio-facio-cutaneous syndrome (n = 1). The phenotype of KRAS mutations was generally severe, including short stature, mental retardation, heart defects, etc. In conclusion, this investigation demonstrates that KRAS mutations are the cause in a minority of cases of Chinese patients with Noonan syndrome in Taiwan.     

Germline p53 mutation presenting as synchronous tumors

Li-Fraumeni syndrome and the LF-like syndrome, rare heritable conditions that predispose to the development of malignancy, are associated with germline mutations of the tumor suppressor gene p53. The authors describe a 14-month-old boy who presented with synchronous rhabdomyosarcoma and adrenal cortical carcinoma and a novel mutation of the p53 gene. Analysis of exons 2 through 11 of the p53 gene using the polymerase chain reaction and DNA sequencing revealed a mutation of codon 273. Although codon 273 is a known hotspot region for p53 mutation, the patient's mutation, R273H, has not been associated with development of adrenal cortical carcinoma.