Heterozygous Missense Mutation In Exon Research Articles

Molecular mechanism analysis of a family with hereditary coagulation F Ⅺ deficiency caused by compound heterozygous mutations

A 34 year old female patient was scheduled to undergo surgical resection due to a "breast nodule". Preoperative examination revealed an activated partial thromboplastin time (APTT) of 66.2 seconds, coagulation factor Ⅺ activity (FⅪ: C) of 2%, and FⅪ antigen (FⅪ: Ag) of 40.3%. The patient and family members showed no abnormal bleeding symptoms. Diagnosed as hereditary coagulation factor Ⅺ deficiency. Genetic testing revealed that the F11 gene had a heterozygous nonsense mutation in exon 10, c.1107C>A (p.Tyr351stop), and a heterozygous missense mutation in exon 13, c.1562A>G (p.Tyr503Cys). The father and son were p Heterozygous carriers of Tyr351stop mutation, while the mother and daughter are p Heterozygous carriers of Tyr503Cys mutations. The in vitro expression results showed that p The Tyr351stop mutation resulted in a significant decrease in the transcription level of F11 gene, while p The Tyr503Cys mutation has no effect on the transcription level and protein expression level of F11 gene, but it leads to a significant decrease in the level of FⅪ:C in the cell culture supernatant.

A novel missense mutation in the MECOM gene in a Chinese boy with radioulnar synostosis with amegakaryocytic thrombocytopenia

Radioulnar synostosis with amegakaryocytic thrombocytopenia (RUSAT) type 2, caused by MDS1 and EVI1 complex locus (MECOM) gene mutations, is a rare inherited bone marrow failure syndrome (IBMFS) with skeletal anomalies, characterized by varying presentation of congenital thrombocytopenia (progressing to pancytopenia), bilateral proximal radioulnar synostosis, and other skeletal abnormalities. Due to limited knowledge and heterogenous manifestations, clinical diagnosis of the disease is challenging. Here we reported a novel MECOM mutation in a Chinese boy with typical clinical features for RUSAT-2. Trio-based whole exome sequencing of buccal swab revealed a novel heterozygous missense mutation in exon 11 of the MECOM gene (chr3:168818673; NM_001105078.3:c.2285G > A). The results strongly suggest that the variant was a germline mutation and disease-causing mutation. The patient received matched unrelated donor hematopoetic stem cell transplantation (HSCT). This finding was not only expanded the pathogenic mutation spectrum of MECOM gene, but also provided key information for clinical diagnosis and treatment of RUSAT-2.

Prime-Editing of human ACTB in induced pluripotent stem cells to model human ACTB Loss-of-Function diseases and compensatory mechanisms

Beta-actin (ACTB) heterozygous loss-of-function mutations are associated with pleiotropic developmental disorders entailing intellectual disability and frequent organ malformations in affected individuals. We generated two CRISPR/Cas9 prime-edited human induced pluripotent stem cell (iPSC) lines, IUFi004-A-1 and IUFi004-A-2, carrying a heterozygous missense mutation in exon 4 of ACTB. Mutant iPSCs exhibited normal cell morphology and genomic integrity, maintained expression of pluripotency markers, and differentiated into the three primary germ layers. The mutants offer a valuable platform for examining the molecular and functional consequences of ACTB haploinsufficiency, developing effective treatments, and exploring mechanisms underlying phenotypic variability and genetic compensation observed in monogenic diseases.

A case of vitamin-D dependent type-1A rickets

Abstract Rickets is a disease of growing bones characterized by softening of bones as a result of defective mineralization of cartilage in the epiphyseal growth plate. The predominant cause is a deficiency or impaired metabolism of vitamin D. Some forms of rickets do not respond to regular doses of cholecalciferol, which leads to suspicion of vitamin D-dependent rickets (VDDR). VDDR is of two types: type I is due to defective renal tubular 25-hydroxyvitamin D 1-α hydroxylase, and type II is due to end-organ resistance to the active metabolite of vitamin D. Here, we describe a child with seizures and calcipenic rickets with biochemical profile suggestive of VDDR type 1 worsened by phenytoin which responded completely to calcium and calcitriol supplementation. Whole exome sequencing revealed a heterozygous missense mutation in exon 7 of the TRPV4 gene (chromosome 12,c.1292C>A), whereas no mutations in CYP2R1, CYP27B1, VDR, and CYP3A4 were detected.

Rare Coexistence of SLC6A9 and TOR1A Gene Mutations in a Neonate Presenting with Hereditary Hyperekplexia and Arthrogryposis Multiplex Congenita: A Case Report with Review of Literature

Background: Neonatal hyperekplexia is a rare nonepileptiform disorder characterized by an exaggerated startle reflex associated with generalized hypertonia. We report a newborn with mutation in the glycinergic inhibition pathway resulting in hyperekplexia, associated with features of arthrogryposis multiplex congenita. Clinical Description: A 3-day-old newborn born at term vaginally cried immediately after birth and presented with lethargy, poor cry, and abnormal clonic movements of all four limbs. On examination, there was hyperreflexia and hypertonia in all four limbs along with dislocation of the right knee joint. Blood investigations, including tandem mass spectrometry, serum ammonia, serum, and cerebrospinal fluid glycine levels, were normal, ruling out inborn errors of metabolism responsible for hyperekplexia and arthrogryposis. The magnetic resonance imaging (MRI) brain and electroencephalogram were normal, while the MRI spine showed kyphosis. The genetic evaluation showed heterozygous missense mutation in exon 6 of the SLC6A9 gene and homozygous mutation in the TOR1A gene, which explained the hyperekplexia and the arthrogryposis multiplex congenita. Management and Outcome: The patient received supportive care. Oral clonazepam and levetiracetam were started in view of hypertonia and clonic spasms. Feeding was given by intragastric tube as he had poor suck–swallow coordination. Conclusions: This case highlights an interesting and extremely rare combination of hereditary hyperekplexia and arthrogryposis multiplex congenita existing together in the same patient, confirmed by the corroborating genetic mutations. Awareness of such conditions among pediatricians is essential to order appropriate genetic evaluations and treatment accordingly.

A novel mutation in the tropomyosin 1 gene in a Chinese patient with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an inherited heart disease characterized by left ventricular hypertrophy. Although sarcomeric gene mutations can explain many HCM cases, the genetic basis of approximately half of HCM cases remains elusive. Here, we report the case of a 30-year-old woman with HCM after imaging and pathological examinations. We identified a novel mutation in a pathogenic gene from the HCM patient through whole-exome sequencing. A heterozygous missense mutation in exon 1 of the α-tropomyosin (TPM1) gene (NM_000366.5:exon1:c.71A > G) was found based on patient sequencing data. The mutation resulted in glutamine replacing arginine (p.Gln24Arg). This mutation was expected to cause significant and deleterious changes in the structure of the TPM1 protein. Therefore, according to pathogenicity assessment guidelines, the mutation was considered likely pathogenic. We found that most of these mutations are related to cardiomyopathy and majority of them are in exon 1 and are missense mutations. TPM1 mutations are thus a common cause of HCM and other congenital heart defects. Thus, a novel missense variant, p.Gln24Arg, in the TPM1 gene is associated with the autosomal dominant disease HCM. These results expand the knowledge spectrum of TPM1 gene function.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) masquerading as CNS demyelination

BackgroundCADASIL is the most common single-gene disorder causing ischemic stroke. CADASIL has been linked to mutations in NOTCH3 gene, due to heterozygous missense mutations. The disease is of insidious onset, presenting with initial clinical features in third and fourth decade of life. However, it is now being increasingly acknowledged that individual clinical presentation, age, time of onset as well as disease severity are quite varied among patients with CADASIL most likely leading to under- or mis-diagnosis. The authors thereby report a genetically confirmed case of CADASIL with atypical clinical course and findings.Case presentationA 48-year-old woman presented with complaints of episodic headache, relapsing–remitting neurological illness, progressive cognitive impairment, and acute-onset loss of speech and ambulation. She was earlier being treated as a case of CNS demyelination for 10 years. On examination, vital parameters were within normal limits. Neurological examination revealed that the patient was drowsy, not verbalizing, not obeying commands, with movement of all four limbs on painful stimuli, hypertonia of all limbs, grade 3 + deep tendon reflexes, bilateral striatal toe and extensor plantar response. Magnetic resonance imaging of brain showed involvement of anterior temporal lobe and external capsule along with multiple acute infarcts. Cerebrospinal fluid analysis was found to be normal. Exome sequencing revealed heterozygous missense mutation in exon 2 of NOTCH3 gene. A definite diagnosis of CADASIL was made and patient was started on fluoxetine and aspirin, following which there was significant improvement over 4–6 weeks. Patient is able to carry out daily activities independently although continues to have mild persistent cognitive impairment with excessive talking and over familiarity.ConclusionsAs CADASIL has a relapsing and partially remitting course with frequently observed varied clinical presentation, patients may receive treatment for demyelination which may not be necessary. Hence, detailed family history along with knowledge of characteristic magnetic resonance imaging findings seen in CADASIL can help discern the diagnosis.

Red cell adenylate kinase deficiency in China: molecular study of 2 new mutations (413G > A, 223dupA)

BackgroundAdenylate kinase (AK) is a monomolecular enzyme widely found in a variety of organisms. It mainly catalyses the reversible transfer of adenosine nucleotide phosphate groups and plays an important role in maintaining energy metabolism. AK deficiency is a rare genetic disorder that is related to haemolytic anaemia. Chronic haemolytic anaemia associated with AK deficiency is a rare condition, and only 14 unrelated families have been reported thus far. Moreover, only 11 mutations have been identified in the AK1 gene, with only 3 cases of psychomotor impairment.Case presentationThe patient was a 3-year-old boy with severe haemolytic anaemia and psychomotor retardation. A molecular study of the patient’s AK gene revealed 2 different mutations: a heterozygous missense mutation in exon 6 (c.413G > A) and a heterozygous frameshift mutation in exon 5 (c.223dupA). Molecular modelling analyses indicated that AK gene inactivation resulted in a lack of AK activity. The patient recovered after regular blood transfusion therapy.ConclusionsAK1 deficiency was diagnosed on the basis of low enzymatic activity and the identification of a mutation in the AK1 gene located on chromosome 9q. Here, we report the first case of moderate red cell AK1 deficiency associated with chronic nonspherocytic haemolytic anaemia (CNSHA) in China. The genetic mutations were confirmed by Sanger sequencing. The variants were classified as pathogenic by bioinformatics tools, such as ACMG/AMP guidelines, Mutation Taster, SIFT, MACP, REVEL and PolyPhen2.2. Based on our evidence and previous literature reports, we speculate that the site of the AK1 gene c.413G > A (p.Arg138His) mutation may be a high-frequency mutation site and the other mutation (c.223dupA) might be related to the neuropathogenicity caused by AK1 deficiency. NGS should be a part of newborn to early childhood screening to diagnose rare and poorly diagnosed genetic diseases as early as possible.

TP53 Expression and Mutational Analysis in Hematological Malignancy in Jeddah, Saudi Arabia.

Background: Tumor protein 53 (TP53) is a tumor-suppressor gene and plays an essential role in apoptosis, cell cycle arrest, genomic stability, and DNA repair. Although it is the most often mutated gene in human cancer, it has respectively low frequency in hematological malignancy but is significantly linked with complex karyotype, poor prognosis, and chemotherapeutic response. Nevertheless, the prevalence and prognostic role of TP53 mutations in hematological malignancy in Saudi patients are not well reported. We, therefore, aim to assess the frequency of TP53 mutations in hematological malignancies in Saudi Arabia. Method: 20 different hematological malignancy samples were tested using fluorescence in situ hybridization (FISH) technique for TP53 deletion detection and next-generation sequencing (NGS) targeted panel was applied on 10 samples for mutations identification specifically TP53 mutation. Results: TP53 deletion was detected in 6 of 20 samples by FISH. Most of the 6 patients with TP53 deletion had acute lymphoblastic leukemia (ALL), and majority of them were child. NGS result revealed one heterozygous missense mutation in exon 5 of the TP53 gene (c. G9963A, p.H175R). Conclusion: To the best of our knowledge, the TP53 mutation is novel variant, and the first time we are reporting their association with myelodysplastic syndromic individual with complex karyotype. This study recommends further analysis of genomic mutations on bigger cohorts, utilizing high throughput technologies.

Joubert syndrome: unusual story

Joubert syndrome (JS) is a rare autosomal recessive neurodevelopmental disorder characterized by hypotonia, ataxia, developmental delay, intellectual disability, abnormal eye movements and abnormal breathing pattern. It has a variable phenotype which makes it difficult to diagnose. We presented a case of a 14 month old girl with delayed developmental milestones and feeding difficulties. MRI brain of this patient in contrast to the classical molar tooth appearance showed only mild corticocerebral atrophy. Gene study revealed a heterozygous missense mutation in exon 1 of the INPP5E gene. Although our patient did not fulfil all three diagnostic criteria for JS, on gene sequencing, there was a missense mutation in one of the commonly found genes for JS. She was managed by a multidisciplinary approach including physical and speech therapy.

Autoinflammation with arthritis and dyskeratosis an inflammasomopathy: Case report and review of literature

Inherited disorders of the inflammasome pathway causes dysregulated inflammasome activation, which presents with inflammation and other clinical features linked to the defective protein. Eight mutations have been previously described in the NLRP1 inflammasome protein, causing different inflammatory skin disorders. Two of these mutations are associated with “autoinflammation with arthritis and dyskeratosis (AIADK),” a novel Mendelian auto-inflammatory disorder, in the 2017 International Union of Immunological Societies phenotypic classification for primary immunodeficiencies. We report a 22-year-old female, with recurrent generalized urticaria, periodic fever and pain abdomen, inflammatory polyarthritis, cutaneous lesions over the extremities, and persistently elevated inflammatory markers. On next-generation sequencing, a heterozygous missense mutation in exon 4 of the NLRP1 gene (chr17:G.5461839C>T) was detected, which results in the amino acid substitution of glutamine for arginine at codon 726 (c.2177G>A; p.Arg726Gln). A probable diagnosis of AIADK, possibly caused by this mutation was proposed, and patient responded well to colchicine.

Generation of pulmonary arterial hypertension patient-specific induced pluripotent stem cell lines from three unrelated patients with a heterozygous missense mutation in exon 12, a heterozygous in-frame deletion in exon 3 and a missense mutation in exon 11 of the BMPR2 gene

Loss-of-function mutations in the bone morphogenetic protein receptor 2 (BMPR2) gene are common in heritable or idiopathic pulmonary arterial hypertension (PAH), and can result in functional impairment of both endothelial and vascular smooth muscle cells. Here, we report 3 PAH patient-specific induced pluripotent stem cells (iPSC) lines from 3 unrelated patients harbouring different mutations in the BMPR2 gene: a heterozygous missense mutation in exon 12, a heterozygous frame shift deletion in exon 3, and a heterozygous missense mutation in exon 11. These cell lines will serve as a valuable resource to model PAH in vitro.

Analysis of a pedigree with inherited factor V deficiency caused by compound heterozygous mutation

目的探讨一个遗传性凝血因子Ⅴ（FⅤ）缺陷症家系的分子致病机制。方法DNA直接测序法分析先证者F5的全部外显子、侧翼序列、5′和3′端非翻译区及家系成员（共3代11人）相应的突变位点区域。通过CAT法检测凝血酶生成量；用ClustalX软件分析突变位点的保守性；用MutationTaster、PolyPhen-2、PROVEAN、LRT和SIFT等在线生物信息学软件预测突变位点对蛋白质功能的影响；用Swiss-PdbViewer软件分析氨基酸突变前后蛋白模型及分子间作用力的变化。结果先证者F5第8外显子存在c.1258G>T杂合错义突变（p.Gly392Cys）及第14外显子存在c.4797delG杂合缺失突变，导致框移并产生截断蛋白（p.Glu1572Lys fsX19）；其祖父和父亲存在p.Gly392Cys杂合突变；其外祖母、母亲、小姨母和表妹均存在p.Glu1572Lys fsX19杂合突变。先证者凝血酶生成延迟和达峰时间比值明显增高。保守性分析结果表明，p.Gly392在10种同源物种中位于保守区域。五个在线生物信息学软件对p.Gly392Cys预测均显示为致病的突变，Mutation Taster对p.Glu1572Lys fsX19预测也显示为致病突变。蛋白模型分析显示，Gly392突变为Cys392后可导致原有氢键延长，并形成新的空间位阻，影响蛋白结构的稳定性。结论该家系F5第8外显子c.1258G>T杂合错义突变及第14外显子c.4797delG杂合缺失突变可能与该家系FⅤ水平降低有关。

Novel mutation of GJA8 in autosomal dominant congenital cataracts.

BackgroundCongenital cataracts is the most common cause of childhood visual impairment and blindness worldwide. It is reported that about one quarter of congenital cataracts caused by genetic defects. Various gene mutations have been identified in hereditary cataracts so far. The purpose of the present study was to investigate the relationship between gap junction protein alpha 8 (GJA8) gene mutation and congenital cataract.MethodsA pedigree with autosomal dominant congenital cataract was investigated and the peripheral venous blood was extracted from 18 family members. After the high-throughput targeted capture and whole exome sequencing for the proband, bioinformatics analysis was performed. By combining the proband clinical symptoms, candidate variations were eliminated which were significantly not consistent with the clinical phenotype. And disease-causing variant was identified.ResultsGene sequencing revealed the heterozygous missense mutation in exon 2 of the GJA8 gene (c.178G>A), which co-segregated with the disease phenotype in the family and resulted in the substitution of glycine to serine at position 178 (p.G60S). This missense mutation was located in the hotspot mutation region, and might be harmful.ConclusionsThis study reports a novel disease-causing sequence variant in the gap junctional protein encoding genes causing autosomal dominant congenital cataract in the Chinese population, caused by the missense mutation of GJA8 (c.178G>A). Our data expand the spectrum of GJA8 variants and associated phenotypes, facilitate clinical diagnosis and support the presence of relationship between genetic basis and human disease.

Novel mutations in the EPO-R, VHL and EPAS1 genes in the Congenital Erythrocytosis patients

Congenital erythrocytosis (CE) can be classified as primary and secondary and 82 consecutive patients of erythrocytosis who were JAK-2 mutation negative, were further investigated. The genomic DNA was extracted from all the patients and the EPO-R, VHL, EGLN1 and EPAS1 genes were PCR amplified and sequenced. The sequence analysis showed (28/82) 34.14% patients had mutations. Among them, (19/28) 67.86% patients had mutations in exon 8 of EPO-R gene, of which six were novel missense mutations, p.(Gly418Ala), p.(Gly390Ala), p.(Ala411Thr), p.(Gly475Val), p.(Glu490Asp), p.(Glu362Gln) and three were novel frameshift mutations, p.(Glu336*), p.(Pro327Hisfs*68), p.(Gly479Alafs*37). All these EPO-R patients were heterozygotes and were forming endogenous erythrocyte colonies (EEC). Some patients (8/28) 28.57% had mutations in VHL gene, out of which 3 novel homozygous missense mutations in exon 1 of VHL gene, p.Gly80Asp, p.Gln107Glu and p.Gln113Glu, were identified. In addition, (1/28) 3.5% patients had one reported heterozygous missense mutation in exon 12 of EPAS1 gene p.Gly537Arg and one novel frameshift mutation p.(Ala553Glyfs*58). Further, in silico analysis indicated most of the mutations, probably, were damaging the protein structures, causing the CE in these patients. In this study the mutations in EPO-R and EPAS1 genes were identified for the first time in India.

Combinatorial approach of in silico and in vitro evaluation of MLH1 variant associated with Lynch syndrome like metastatic colorectal cancer.

Colorectal cancer (CRC) is the third most developing cancer worldwide and Lynch syndrome (LS) accounts for 3–4% of CRC. Genetic alteration in any of DNA mismatch repair (MMR) gene is the major cause of LS that disrupt the normal upstream and downstream MMR events. Germline mutation of MLH1 in heterozygous state have an increased risk for CRC. Defective MMR pathway mostly results in microsatellite instability (MSI) that occurs in high percentage of CRC associated tumors. Here, we reported a patient with LS like metastatic CRC (mCRC) associated with other related cancers. Whole exome sequencing (WES) of the proband was performed to identify potential causative gene. Genetic screening validated by Sanger sequencing identified a heterozygous missense mutation in exon 12 of MLH1 (c.1151T>A, p.V384D). The clinical significance of identified variant was elucidated on the basis of clinicopathological data, computational predictions and various in vitro functional analysis. In silico predictions classified the variant to be deleterious and evolutionary conserved. In vitro functional studies revealed a significant decrease in protein expression because of stability defect leading to loss of MMR activity. Mutant residue found in MutL transducer domain of MLH1 that localized in the nucleus but translocation was not found to be significantly disturbed. In conclusion, our study give insight into reliability of combinatorial prediction approach of in silico and in vitro expression analysis. Hence, we highlighted the pathogenic correlation of MLH1 variant with LS associated CRC as well as help in earlier diagnosis and surveillance for improved management and genetic counselling.

Disseminated Talaromyces marneffei infection presenting as multiple intestinal perforations and diffuse hepatic granulomatous inflammation in an infant with STAT3 mutation: a case report

BackgroundTalaromyces marneffei is a highly pathogenic fungus that can cause life-threatening fatal systemic mycosis. Disseminated Talaromycosis marneffei affects multiple organs, including the lungs, skin, and reticuloendothelial system. However, T. marneffei infection has rarely been reported in human immunodeficiency virus (HIV)-negative infants with multiple intestinal perforations and diffuse hepatic granulomatous inflammation.Case presentationWe present the case of an HIV-negative 37-month-old boy who has had recurrent pneumonia since infancy and was infected with disseminated Talaromycosis. Contrast-enhanced computed tomography of the whole abdomen showed hepatomegaly and intestinal wall thickening in the ascending colon and cecum with mesenteric lymphadenopathy. Colonoscopy showed a cobblestone pattern with erosion, ulcer, polypoid lesions, and lumen deformation ranging from the colon to the cecum. T. marneffei was isolated from the mucous membrane of the colon, liver, and bone marrow. After antifungal treatment and surgery, his clinical symptoms significantly improved. Whole-exome sequencing using the peripheral blood of the patient and his parents’ revealed a heterozygous missense mutation in exon 17 of the STAT3 gene (c.1673G>A, p.G558D).ConclusionsIn T. marneffei infection-endemic areas, endoscopic examination, culture, or histopathology from the intestine tissue should be performed in disseminated Talaromycosis patients with gastrointestinal symptoms. Timely and systemic antifungal therapy could improve the prognosis. Immunodeficiency typically should be considered in HIV-negative infants with opportunistic infections.

Recurrent pneumothorax and intrapulmonary cavitary lesions in a male patient with vascular Ehlers-Danlos syndrome and a novel missense mutation in the COL3A1 gene: a case report

BackgroundVascular Ehlers-Danlos syndrome (vEDS) is a rare autosomal dominant hereditary collagen disease caused by a defect or deficiency in the pro-α1 chain of type III procollagen encoded by the COL3A1 gene. Patients with vEDS rarely present with multiple pneumothoraces. The clinical features of this disease are not familiar to clinicians and are easily missed. We report a patient with a novel missense mutation in the COL3A1 gene (NM_000090.3: c.2977G > A) and hope to provide clinicians with valuable information.Case presentationWe reported the case of a young man presenting with frequent episodes of pneumothorax and intrapulmonary cavities and nodular lesions without arterial or visceral complications. His skin was thin and transparent, and the joints were slightly hypermobile. Whole-exome sequencing (chip capture high-throughput sequencing) revealed a heterozygous missense mutation in exon 41 of the COL3A1 gene (NM_000090.3: c.2977G > A), confirming the diagnosis of vEDS. vEDS remains a very rare and difficult diagnosis to determine.ConclusionWhen a patient presents with recurrent pneumothorax, intrapulmonary cavities and nodular lesions, thin and transparent skin, and hypermobile joints, clinicians should consider the diagnosis of vEDS.

Bjornstad综合征致病BCS1L基因的新发突变位点研究

Objective To identify gene mutations in the BCS1L gene in a patient with Bjornstad syndrome mainly manifesting as congenital pili torti and sensorineural hearing loss. Methods Clinical data were collected and DNA was extracted from the peripheral blood of the patient and her parents. All the exons and their flanking sequences of the BCS1L gene were amplified by PCR followed by Sanger sequencing, and the sequencing results were compared with the normal sequences. A few hairs were collected from the patient, and examined by the scanning electron microscope. Results There were two mutations in BCS1L gene in the patient, i.e., a heterozygous nonsense mutation in exon 4 and a heterozygous missense mutation in exon 8. The nonsense mutation in exon 4, which caused a change from CGA to TGA at position 144 and resulted in the substitution of arginine by termination codon (p.R144*) , was a novel mutation in the BCS1L gene causing Bjornstad syndrome, and had never been reported in the literature. The missense mutation in exon 8 led to a change from CGC to CAC at position 306 and resulted in the substitution of arginine by histidine (p.R306H) . The patient′s mother only carried a heterozygous mutation c.430 C>T (p.R144*) in exon 4 of the BCS1L gene, and her father only carried a heterozygous mutation c.917 G>A (p.R306H) in exon 8 of the BCS1L gene. Scanning electron microscopy showed that flats, grooves and longitudinal twisting irregularly appeared at intervals on the surface of hair shafts. Conclusions A novel mutation in the BCS1L gene, which causes a change from CGA to TGA at position 144 in the BCS1L gene and results in a premature termination codon, is firstly reported in a patient with Bjornstad syndrome, and the compound heterozygous mutations c.430 C>T and c.917 G>A in the BCS1L gene are associated with the clinical manifestations of the patient. Genetic analysis is helpful for the diagnosis of Bjornstad syndrome. Key words: Mitochondrial diseases; Genes, mitochondrial; DNA mutational analysis; Bjornstad syndrome; BCS1L gene

Cardio-facio-cutaneous syndrome-associated pathogenic MAP2K1 variants activate autophagy

MAP2K1 encodes mitogen-activated protein kinase 1 (MEK1). Mutations in MAP2K1 lead to continuous activation of MEK/ERK signaling pathway, giving rise to cardio-facio-cutaneous syndrome (CFCS). However, the molecular mechanisms of abnormal activation of MEK/ERK signaling pathway and the role of autophagy, if any, in manifesting CFCS in MAP2K mutants remain unclear. Here, we report three Chinese children with CFCS having MAP2K1 pathogenic variants, identified by exome sequencing. They presented with dysmorphic facial features, seizures, psychomotor retardation, and short stature. Additionally, the third child showed pulmonary valve stenosis, multiple skeletal deformities, and osteoporosis. Whole exome sequencing revealed two heterozygous missense mutations in exon 3 of MAP2K1 (c.383G>T; p.Gly128Val and c.389A>G; p.Tyr130Cys), as well as a novel heterozygous missense variant (c.170A>T; p.Lys57Met) in exon 2 of MAP2K1. In SH-SY5Y cells, we identified, for the first time, that MAP2K1 mutations can activate the p-ERK-dependent cell cycle progression and autophagy, and cause CFCS. Our results extended the mutational spectrum of MAP2K1, examined the role of MEK1 protein in nerve cell functions, and demonstrated, for the first time, that autophagy may mediate the altered MAP2K1 function, leading to CFCS phenotypes.