Identification of novel mutations in HEXA gene in children affected with Tay Sachs disease from India

Tay Sachs disease (TSD) is a neurodegenerative disorder due to β-hexosaminidase A deficiency caused by mutations in the HEXA gene. The mutations leading to Tay Sachs disease in India are yet unknown. We aimed to determine mutations leading to TSD in India by complete sequencing of the HEXA gene. The clinical inclusion criteria included neuroregression, seizures, exaggerated startle reflex, macrocephaly, cherry red spot on fundus examination and spasticity. Neuroimaging criteria included thalamic hyperdensities on CT scan/T1W images of MRI of the brain. Biochemical criteria included deficiency of hexosaminidase A (less than 2% of total hexosaminidase activity for infantile patients). Total leukocyte hexosaminidase activity was assayed by 4-methylumbelliferyl-N-acetyl-β-D-glucosamine lysis and hexosaminidase A activity was assayed by heat inactivation method and 4-methylumbelliferyl-N-acetyl-β-D-glucosamine-6-sulphate lysis method. The exons and exon-intron boundaries of the HEXA gene were bidirectionally sequenced using an automated sequencer. Mutations were confirmed in parents and looked up in public databases. In silico analysis for mutations was carried out using SIFT, Polyphen2, MutationT@ster and Accelrys Discovery Studio softwares. Fifteen families were included in the study. We identified six novel missense mutations, c.340 G>A (p.E114K), c.964 G>A (p.D322N), c.964 G>T (p.D322Y), c.1178C>G (p.R393P) and c.1385A>T (p.E462V), c.1432 G>A (p.G478R) and two previously reported mutations. c.1277_1278insTATC and c.508C>T (p.R170W). The mutation p.E462V was found in six unrelated families from Gujarat indicating a founder effect. A previously known splice site mutation c.805+1 G>C and another intronic mutation c.672+30 T>G of unknown significance were also identified. Mutations could not be identified in one family. We conclude that TSD patients from Gujarat should be screened for the common mutation p.E462V.     

Translation initiator EIF4G1 mutations in familial Parkinson disease

Genome-wide analysis of a multi-incident family with autosomal-dominant parkinsonism has implicated a locus on chromosomal region 3q26-q28. Linkage and disease segregation is explained by a missense mutation c.3614G>A (p.Arg1205His) in eukaryotic translation initiation factor 4-gamma (EIF4G1). Subsequent sequence and genotype analysis identified EIF4G1 c.1505C>T (p.Ala502Val), c.2056G>T (p.Gly686Cys), c.3490A>C (p.Ser1164Arg), c.3589C>T (p.Arg1197Trp) and c.3614G>A (p.Arg1205His) substitutions in affected subjects with familial parkinsonism and idiopathic Lewy body disease but not in control subjects. Despite different countries of origin, persons with EIF4G1 c.1505C>T (p.Ala502Val) or c.3614G>A (p.Arg1205His) mutations appear to share haplotypes consistent with ancestral founders. eIF4G1 p.Ala502Val and p.Arg1205His disrupt eIF4E or eIF3e binding, although the wild-type protein does not, and render mutant cells more vulnerable to reactive oxidative species. EIF4G1 mutations implicate mRNA translation initiation in familial parkinsonism and highlight a convergent pathway for monogenic, toxin and perhaps virally-induced Parkinson disease.     

Three novel BRCA1/BRCA2 mutations in breast/ovarian cancer families in Croatia

BRCA1 and BRCA2 genes from 167 candidates (145 families) were scanned for mutations. We identified 14 pathogenic point mutations in 17 candidates, 9 in BRCA1 and 5 in BRCA2. Of those, 11 have been previously described and 3 were novel (c.5335C>T in BRCA1 and c.4139_4140dupTT and c.8175G>A in BRCA2). No large deletions or duplications involving BRCA1 and BRCA2 genes were identified. No founder mutations were detected for the Croatian population. Croatia shares most of the mutations with neighboring Slovenia and also with Germany, Austria and Poland. Two common sequence variants in BRCA1, c.2077G>A and c.4956G>A, were found more frequently in mutation carriers compared to healthy controls. No difference in BRCA2 variants was detected between the groups. Haplotype inference showed no difference in haplotype distributions between deleterious mutation carriers and non-carriers in neither BRCA1 nor BRCA2. In silico analyses identified one BRCA1 sequence variant (c.4039A>G) and two BRCA2 variants (c.5986G>A and c.6884G>C) as harmful with high probability, and inconclusive results were obtained for our novel BRCA2 variant c.3864_3866delTAA. Combination of QMPSF and HRMA methods provides high detection rate and complete coverage of BRCA1/2 genes. Benefit of BRCA1/2 mutation testing is clear, since we detected mutations in young unaffected women, who will be closely monitored for breast and ovarian cancer.     

Late neurological presentations of Wilson disease patients in French population and identification of 8 novel mutations in the ATP7B gene.

Wilson disease (WD) is an autosomal recessive disorder of copper biliary excretion caused by an impaired function of ATP7B, a metal-transporting P-type ATPase encoded by WD gene. It results in copper accumulation, mostly in liver and brain tissues. Mutation analysis was carried out on 11 WD French unrelated patients presenting a predominant neurological form of this illness. SSCP and dHPLC analysis followed by sequencing of the 21 exons and their flanking introns were performed. Thirteen different mutations in a total of 17, and, among them, 10 novel variants were evidenced. Two deletions (c.654_655delCC and c.1745_1746delTA), 4 missense mutations (p.F763Y, p.G843R, p.D918A and p.L979Q), 1 nonsense mutation (p.Q1200X), 1 splice site mutation (c.1947-1G>C) and 2 intronic silent substitutions (c.2448-25G>T and c.3412+13T>A) were detected. These data extend the mutational spectrum of the disease, already known to be a very heterogeneous genetic disorder. As compared to hepatic manifestations, the phenotypes associated to these mutations confirm that neurological presentations associated with other mutations than p.H1069Q are also often late in their onset. Most of these neurological forms probably correspond to an attenuated impairment of copper metabolism, as compared to hepatic forms of the disease, mostly diagnosed earlier.     

Mutations in the HFE, TFR2, and SLC40A1 genes in patients with hemochromatosis

Hereditary hemochromatosis causes iron overload and is associated with a variety of genetic and phenotypic conditions. Early diagnosis is important so that effective treatment can be administered and the risk of tissue damage avoided. Most patients are homozygous for the c.845G>A (p.C282Y) mutation in the HFE gene; however, rare forms of genetic iron overload must be diagnosed using a specific genetic analysis. We studied the genotype of 5 patients who had hyperferritinemia and an iron overload phenotype, but not classic mutations in the HFE gene. Two patients were undergoing phlebotomy and had no iron overload, 1 with metabolic syndrome and no phlebotomy had mild iron overload, and 2 patients had severe iron overload despite phlebotomy. The patients' first-degree relatives also underwent the analysis. We found 5 not previously published mutations: c.-408_-406delCAA in HFE, c.1118G>A (p.G373D), c.1473G>A (p.E491E) and c.2085G>C (p.S695S) in TFR2; and c.-428_-427GG>TT in SLC40A1. Moreover, we found 3 previously published mutations: c.221C>T (p.R71X) in HFE; c.1127C>A (p.A376D) in TFR2; and c.539T>C (p.I180T) in SLC40A1. Four patients were double heterozygous or compound heterozygous for the mutations mentioned above, and the patient with metabolic syndrome was heterozygous for a mutation in the TFR2 gene. Our findings show that hereditary hemochromatosis is clinically and genetically heterogeneous and that acquired factors may modify or determine the phenotype.     

Mutations in C5ORF42 cause Joubert syndrome in the French Canadian population

Joubert syndrome (JBTS) is an autosomal-recessive disorder characterized by a distinctive mid-hindbrain malformation, developmental delay with hypotonia, ocular-motor apraxia, and breathing abnormalities. Although JBTS was first described more than 40 years ago in French Canadian siblings, the causal mutations have not yet been identified in this family nor in most French Canadian individuals subsequently described. We ascertained a cluster of 16 JBTS-affected individuals from 11 families living in the Lower St. Lawrence region. SNP genotyping excluded the presence of a common homozygous mutation that would explain the clustering of these individuals. Exome sequencing performed on 15 subjects showed that nine affected individuals from seven families (including the original JBTS family) carried rare compound-heterozygous mutations in C5ORF42. Two missense variants (c.4006C>T [p.Arg1336Trp] and c.4690G>A [p.Ala1564Thr]) and a splicing mutation (c.7400+1G>A), which causes exon skipping, were found in multiple subjects that were not known to be related, whereas three other truncating mutations (c.6407del [p.Pro2136Hisfs*31], c.4804C>T [p.Arg1602*], and c.7477C>T [p.Arg2493*]) were identified in single individuals. None of the unaffected first-degree relatives were compound heterozygous for these mutations. Moreover, none of the six putative mutations were detected among 477 French Canadian controls. Our data suggest that mutations in C5ORF42 explain a large portion of French Canadian individuals with JBTS.     

SARS冠状病毒S蛋白候选细胞受体氨基肽酶N的基因变异研究

氨基肽酶N是人类冠状病毒HCoV 2 2 9E的细胞受体 ,可能为SARS冠状病毒 (SARS CoV)S蛋白的受体。应用变性高效液相色谱 (DHPLC)技术筛查了正常无关个体中氨基肽酶N编码基因ANPEP的全部外显子及其两侧部分内含子序列。对筛查中DHPLC峰型提示有基因变异存在的DNA片段行PCR产物直接测序 ,共发现 9种单核苷酸多态 (SNP) ,其中 4种为非同义SNP ,分别为T32 1M(96 2C >T)、S6 5 1L(195 2C >T)、S75 2N(2 2 5 5G >A)和G76 4R(2 2 90G >A) ;其余 5种SNP为T795T(2 385C >T)、IVS7+17G >A、IVS14 16A >G、IVS17+12C >G和IVS17+44C >T。这些SNP的发现 ,为SARS CoV的宿主遗传因素研究 ,特别是发现SARS CoV感染和SARS发病的易感基因或抗病基因 ,提供了遗传标记。     

Whole exome sequence analysis of Peters anomaly

Peters anomaly is a rare form of anterior segment ocular dysgenesis, which can also be associated with additional systemic defects. At this time, the majority of cases of Peters anomaly lack a genetic diagnosis. We performed whole exome sequencing of 27 patients with syndromic or isolated Peters anomaly to search for pathogenic mutations in currently known ocular genes. Among the eight previously recognized Peters anomaly genes, we identified a de novo missense mutation in PAX6, c.155G>A, p.(Cys52Tyr), in one patient. Analysis of 691 additional genes currently associated with a different ocular phenotype identified a heterozygous splicing mutation c.1025+2T>A in TFAP2A, a de novo heterozygous nonsense mutation c.715C>T, p.(Gln239*) in HCCS, a hemizygous mutation c.385G>A, p.(Glu129Lys) in NDP, a hemizygous mutation c.3446C>T, p.(Pro1149Leu) in FLNA, and compound heterozygous mutations c.1422T>A, p.(Tyr474*) and c.2544G>A, p.(Met848Ile) in SLC4A11; all mutations, except for the FLNA and SLC4A11 c.2544G>A alleles, are novel. This is the first study to use whole exome sequencing to discern the genetic etiology of a large cohort of patients with syndromic or isolated Peters anomaly. We report five new genes associated with this condition and suggest screening of TFAP2A and FLNA in patients with Peters anomaly and relevant syndromic features and HCCS, NDP and SLC4A11 in patients with isolated Peters anomaly.     

Nucleotide diversity of the melanocortin 1 receptor gene (MC1R) in the gayal (Bos frontalis)

The melanocortin 1 receptor gene (MC1R) plays a crucial role in determining coat colour of mammals. To investigate the relationship of polymorphism of the MC1R with coat colour in gayal, the coding sequence (CDS), and the 5'- and 3'-untranslated regions (UTR) of the MC1R were sequenced from 63 samples from the gayal and compared with the sequences of the MC1R from other ruminant species. A sequence of 1,136 bp including the whole CDS (954 bp) and parts of the 5'- and 3'-UTR (164 and 18 bp, respectively) of the gayal MC1R was obtained. A total of nine single nucleotide polymorphisms (SNPs) including four SNPs (c.-129T>C, c.-127A>C, c.-106C>T, c.-1G>A) in the 5'-UTR and five SNPs (c.201C>T, c.583C>T, c.663T>C, c.871A>G and c.876T>C) in the CDS were detected, revealing high genetic diversity. Three novel coding SNPs including c.201C>T, c.583C>T and c.876T>C, which have not been reported previously in bovid species, were retrieved. Within five coding SNPs, c.201C>T, c.663T>C and c.876T>C were silent mutations, while c.583C>T and c.871A>G were mis-sense mutations, resulting in changes in the amino acids located in the fifth (p.L195F) and seventh (p.T291A) transmembrane regions, respectively. The alignment of amino acid sequences was found to be very similar to those for other bovid species. It was demonstrated, using the functional effect prediction, that the p.T291A amino acid replacement could have an effect on MC1R protein function but not for the p.L195F substitution. Using phylogenetic analyses it was revealed that the gayal has a close genetic relationship with the yak. However, three classical bovine MC1R loci the E (D), E (+) and e were not retrieved in the gayal, indicating other genes or factors could affect coat colour in this species.     

Common mutations of familial hypercholesterolemia patients in Taiwan: characteristics and implications of migrations from southeast China

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by mutations in low-density lipoprotein receptor (LDLR), apolipoprotein B-100 (APOB), and proprotein convertase subtilisin/kexin type 9 (PCSK9) genes. This study investigated FH patients carrying common mutations in Taiwan and compared them to FH southeastern Asians. Causal FH mutations were identified by exon-by-exon sequencing with/without multiplex ligation-dependent probe amplification among 208 Taiwanese with clinically diagnosed FH. Haplotype analyses among probands and family members were undertaken using TaqMan® Assays. Totally, LDLR mutations were found in 118 probands, consisting of 61 different loci, and APOB 10579C>T mutations in 12 probands. Three mutations (64delG, 1661C>T, and 2099A>G) were novel. LDLR 986G>A (13.1%), 1747C>T (10.8%), and APOB 10579C>T (9.2%) were common mutations with no differences in phenotypes. LDLR 1747C>T associated with one haplotype (CAAGCCCCATGG/(dTA)n-112nt); LDLR 986G>A with two. APOB 10579C>T associated with the same LDLR binding-domain pattern in Taiwanese and southeastern Asians. We concluded that LDLR 986G>A, 1747C>T and APOB 10579C>T are common mutations, with combined frequency of approximately 33%. The presence of different haplotypes associated with FH common mutations in Taiwan indicates multiple historical migrations, probable multiple recurrent origins from southern China, and haplotype homologies reflect the presence of common ancestors in southern China.     

A low prevalence of MYH7/MYBPC3 mutations among Familial Hypertrophic Cardiomyopathy patients in India

Familial Hypertrophic Cardiomyopathy (FHC) is an autosomal dominant disorder affecting the cardiac muscle and exhibits varied clinical symptoms because of genetic heterogeneity. Several disease causing genes have been identified and most code for sarcomere proteins. In the current study, we have carried out clinical and molecular analysis of FHC patients from India. FHC was detected using echocardiography and by analysis of clinical symptoms and family history. Disease causing mutations in the β-cardiac myosin heavy chain (MYH7) and Myosin binding protein C3 (MYBPC3) genes were identified using Polymerase Chain Reaction-Deoxyribose Nucleic Acid (PCR-DNA) sequencing. Of the 55 patient samples screened, mutations were detected in only nineteen in the two genes; MYBPC3 mutations were identified in 12 patients while MYH7 mutations were identified in five, two patients exhibited double heterozygosity. All four MYH7 mutations were missense mutations, whereas only 3/9 MYPBC3 mutations were missense mutations. Four novel mutations in MYBPC3 viz. c.456delC, c.2128G>A (p.E710K), c.3641G>A (p.W1214X), and c.3656T>C (p.L1219P) and one in MYH7 viz. c.965C>T (p.S322F) were identified. A majority of missense mutations affected conserved amino acid residues and were predicted to alter the structure of the corresponding mutant proteins. The study has revealed a greater frequency of occurrence of MYBPC3 mutations when compared to MYH7 mutations.     

Molecular analysis of HEXA gene in Argentinean patients affected with Tay-Sachs disease: possible common origin of the prevalent c.459+5A>G mutation

Tay-Sachs disease (TSD) is a recessively inherited disorder caused by the deficient activity of hexosaminidase A due to mutations in the HEXA gene. Up to date there is no information regarding the molecular genetics of TSD in Argentinean patients. In the present study we have studied 17 Argentinean families affected by TSD, including 20 patients with the acute infantile form and 3 with the sub-acute form. Overall, we identified 14 different mutations accounting for 100% of the studied alleles. Eight mutations were novel: 5 were single base changes leading to drastic residue changes or truncated proteins, 2 were small deletions and one was an intronic mutation that may cause a splicing defect. Although the spectrum of mutations was highly heterogeneous, a high frequency of the c.459+5G>A mutation, previously described in different populations was found among the studied cohort. Haplotype analysis suggested that in these families the c.459+5G>A mutation might have arisen by a single mutational event.     

Mutations in FYCO1 cause autosomal-recessive congenital cataracts

Congenital cataracts (CCs), responsible for about one-third of blindness in infants, are a major cause of vision loss in children worldwide. Autosomal-recessive congenital cataracts (arCC) form a clinically diverse and genetically heterogeneous group of disorders of the crystalline lens. To identify the genetic cause of arCC in consanguineous Pakistani families, we performed genome-wide linkage analysis and fine mapping and identified linkage to 3p21-p22 with a summed LOD score of 33.42. Mutations in the gene encoding FYVE and coiled-coil domain containing 1 (FYCO1), a PI(3)P-binding protein family member that is associated with the exterior of autophagosomes and mediates microtubule plus-end-directed vesicle transport, were identified in 12 Pakistani families and one Arab Israeli family in which arCC had previously been mapped to the overlapping CATC2 region. Nine different mutations were identified, including c.3755 delC (p.Ala1252AspfsX71), c.3858_3862dupGGAAT (p.Leu1288TrpfsX37), c.1045 C>T (p.Gln349X), c.2206C>T (p.Gln736X), c.2761C>T (p.Arg921X), c.2830C>T (p.Arg944X), c.3150+1 G>T, c.4127T>C (p.Leu1376Pro), and c.1546C>T (p.Gln516X). Fyco1 is expressed in the mouse embryonic and adult lens and peaks at P12d. Expressed mutant proteins p.Leu1288TrpfsX37 and p.Gln736X are truncated on immunoblots. Wild-type and p.L1376P FYCO1, the only missense mutant identified, migrate at the expected molecular mass. Both wild-type and p. Leu1376Pro FYCO1 proteins expressed in human lens epithelial cells partially colocalize to microtubules and are found adjacent to Golgi, but they primarily colocalize to autophagosomes. Thus, FYCO1 is involved in lens development and transparency in humans, and mutations in this gene are one of the most common causes of arCC in the Pakistani population.     

Corticotropin releasing hormone is a promising candidate gene for marbling and subcutaneous fat depth in beef cattle.

The gene corticotropin releasing hormone (CRH) is mapped on bovine chromosome 14 (BTA14), where more than 30 fat-related quantitative trait loci (QTLs) have been reported in dairy and beef cattle. The gene product regulates secretion of adrenocorticotrophin hormone, the hypothalamic-pituitary-adrenal axis, and multiple hypothalamic functions; therefore, we hypothesized that CRH is a promising candidate gene for beef marbling score (BMS) and subcutaneous fat depth (SFD) in a Wagyu x Limousin F2 population. Two pairs of primers were designed and a total of 5 single nucleotide polymorphisms (SNPs) were identified: g.9657C>T, c.10718G>C, c.10841G>A, c.10893A>C, and c.10936G>C (AAFC03076794.1). Among the 4 cSNPs, c.10718G>C, c.10841G>A, and c.10936G>C are missense mutations leading to amino acid changes from arginine to proline, from serine to asparagine, and from aspartic acid to histidine, respectively. These 5 SNPs were genotyped on ~250 F2 progeny, but only 4 were selected as tagging SNPs for association analysis because no historical recombination was observed between c.10718G>C and c.10893A>C. Statistical analysis showed that g.9657C>T, c.10718G>C, and c.10936G>C and their haplotypes had significant effects on SFD, but only c.10936G>C was significantly associated with BMS. The SNP in the promoter (g.9657C>T) led to gain/loss of a CpG site and 4 potential regulatory binding sites. Different haplotypes among the 4 cSNPs significantly affected mRNA secondary structures but were not associated with phenotypes. Overall, our results provide further evidence that CRH is a promising candidate gene for a concordant QTL related to lipid metabolism in mammals.     

Vascular endothelial growth factor gene polymorphisms and colorectal cancer risk: a meta-analysis

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen involved in a number of pathologic processes, including angiogenesis, tumor growth and metastasis. Polymorphisms of the VEGF gene have been associated with susceptibility to colorectal cancer (CRC). However, the specific association still remains controversial. We made a meta-analysis of the association between VEGF gene polymorphisms and CRC risk. Only eight case-control studies were retrieved, with a total of 2337 CRC patients and 2032 healthy controls. Six VEGF gene polymorphisms were addressed in all studies included, +936C>T (rs3025039), -2578C>A (rs699947), -1154G>A (rs1570360), -634G>C (rs2010963), -460C>T (rs833061), and +405C>G (rs2010963). There was a significant association between -2578C>A polymorphism and susceptibility to CRC in the comparison of C allele carriers (CC + CA) versus AA (odds ratio = 0.77, 95% confidence interval = 0.62-0.96, P = 0.02). No association was found between +936C>T, -1154G>A, -634G>C, -460C>T, and +405C>G with susceptibility to CRC. We conclude that the C allele carrier (CC + CA) of VEGF -2578C>A polymorphism appears to be a protective factor for CRC.     

Two novel mutations and a previously unreported intronic polymorphism in the NOTCH3 gene

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary disease of small vessel caused by mutations in the NOTCH3 gene (NCBI Gene ID: 4854) located on chromosome 19p13.1. NOTCH3 consists of 33 exons which encode a protein of 2321 amino acids. Exons 3 and 4 were found to be mutation hotspots, containing more than 65% of all CADASIL mutations. We performed direct sequencing on an ABI 3130 Genetic Analyser to screen for mutations and polymorphisms on 300 patients who were clinically suspected to have CADASIL. First, exons 3 and 4 were screened in NOTCH3 and if there were no variations found, then extended CADASIL testing (exons 2, 11, 18 and 19) was offered to patients. Here we report two novel non-synonymous mutations identified in the NOTCH3 gene. The first mutation, located in exon 4 was found in a 49-year-old female and causes an alanine to valine amino acid change at position 202 (605C>T). The second mutation, located in exon 11, was found in a 66-year-old female and causes a cysteine to arginine amino acid change at position 579 (1735T>C). We also report a 46-year-old male with a known polymorphism Thr101Thr (rs3815188) and an unreported polymorphism NM_000435.2:c.679+60G>A observed in intron 4 of the NOTCH3 gene. Although Ala202Ala (rs1043994) is a common polymorphism in the NOTCH3 gene, our reported novel mutation (Ala202Val) causes an amino acid change at the same locus. Our other reported mutation (Cys579Arg) correlates well with other known mutations in NOTCH3, as the majority of the CADASIL-associated mutations in NOTCH3 generally occur in the EGF-like (epidermal growth factor-like) repeat domain, causing a change in the number of cysteine residues. The intronic polymorphism NM_000435.2:c.679+60G>A lies close to the intron-exon boundary and may affect the splicing mechanism in the NOTCH3 gene.     

Identification of novel and recurrent mutations in the calcium binding type III repeats of cartilage oligomeric matrix protein in patients with pseudoachondroplasia

Pseudoachondroplasia is an autosomal dominant osteochondrodysplasia characterized by disproportionate short stature, joint laxity, and early onset osteoarthrosis. Pseudoachondroplasia is caused by mutations in the gene encoding cartilage oligomeric matrix protein (COMP). We looked for mutations in the COMP gene in three sporadic Chinese pseudoachondroplasia patients and identified two novel mutations, c.1189G>T (p.D397Y) and c.1220G>A (p.C407Y), and one recurrent mutation, c.1318G>C (p.G440R), in the calcium binding type III repeats of COMP. This study confirms the relationship between mutations of the COMP gene and clinical findings of pseudoachondroplasia; it also provides evidence for the importance of the calcium binding domains to the functioning of COMP.     

猪Toll样受体4基因SNPs功能分析

Toll样受体4(Toll-like receptor 4,TLR4)在机体的免疫反应中发挥重要作用,该基因突变会影响受体的信号转导能力和机体的疾病抗性/易感性。文章在前期工作的基础上,进一步分析c.611 T>A(p.Leu204His)、c.1027C>A(p.Gln343Lys)和c.1605 G>T(p.Leu535Phe)3个错义突变对猪TLR4功能的影响。利用RT-PCR方法克隆猪TLR4基因全长编码区并引入定点突变;利用真核表达、双荧光素酶报告系统和Western blotting方法在瞬时转染的PK-15细胞内研究3个单核苷酸多态(Single nucleotide polymorphisms,SNPs)对猪TLR4配体识别和信号转导能力的影响;同时,利用创造酶切位点PCR-RFLP方法分析对TLR4活性有显著影响的点突变在民猪、大白、长白和中国东北野猪4个群体中的分布。结果,成功获得了民猪TLR4基因的全长编码区和3个单碱基变异体,构建了不同等位基因的真核表达载体,在PK-15细胞内确定了c.1605 G>T变异导致TLR4向下游传递信号的能力显著降低(P<0.01),该SNP只存在于民猪和野猪中且频率较高。猪TLR4基因c.1605 G>T变异影响Toll样受体的信号传递,可能和机体的疾病抗性/易感性有关。     

Whole-exome sequencing identifies mutations of KIF22 in spondyloepimetaphyseal dysplasia with joint laxity, leptodactylic type

Spondyloepimetaphyseal dysplasia with joint laxity (SEMDJL), leptodactylic (lepto-SEMDJL) or Hall type, is an autosomal-dominant skeletal dysplasia manifesting with short stature, joint laxity with dislocation(s), limb malalignment, and spinal deformity. Its causative gene mutation has not yet been discovered. We captured and sequenced the exomes of eight affected individuals in six unrelated kindreds (three individuals in a family and five simplex individuals). Five novel sequence variants in KIF22, which encodes a member of the kinesin-like protein family, were identified in seven individuals. Sanger sequencing of KIF22 confirmed that c.443C>T (p.Pro148Ser) cosegregated with the phenotype in the affected individuals in the family; c.442C>T (p.Pro148Leu) or c.446G>A (p.Arg149Gln) was present in four of five simplex individuals, but was absent in unaffected individuals in their family and 505 normal cohorts. KIF22 mRNA was detected in human bone, cartilage, joint capsule, ligament, skin, and primary cultured chondrocytes. In silico analysis of KIF22 protein structure indicates that Pro148 and Arg149 are important in maintaining hydrogen bonds in the ATP binding and motor domains of KIF22. We conclude that these mutations in KIF22 cause lepto-SEMDJL.