Polymorphonuclear leukocytes from individuals carrying the G329A mutation in the alpha 1,3-fucosyltransferase VII gene (FUT7) roll on E- and P-selectins

We recently identified several individuals carrying a missense mutation (G329A; Arg(110)-Gln) in the FUT7 gene encoding fucosyltransferase VII. This enzyme is involved in the biosynthesis of the sialyl Lewis x (Le(x)) epitope on human leukocytes, which has been identified as an important component of leukocyte ligands for E- and P-selectin. No enzyme activity was measurable in expression studies in COS-7 cells using the mutated FUT7 construct. One of the identified individuals carried this mutation homozygously. Flow cytometry analysis of polymorphonuclear leukocytes (PMN) from this individual showed a nearly complete absence of staining with mAbs directed against sialyl Le(x) and a diminished staining with an E-selectin IgG chimera. However, staining with P-selectin IgG chimera and Abs directed against P-selectin glycoprotein ligand-1 was not affected by the mutation. PMN from the homozygously mutated individual was further analyzed in an in vitro flow chamber assay. The number of rolling PMN and the rolling velocities on both E- and P-selectin were in the range of PMN from nonmutated individuals. FUT4 and FUT7 mRNA was quantified in PMN isolated from individuals carrying the FUT7 mutation. It was found that PMN from both FUT7 homozygously and heterozygously mutated individuals exhibited an elevated expression of FUT4 mRNA compared with PMN from FUT7 nonmutated individuals. The elevated expression of fucosyltransferase IV was reflected as an increased expression of the Le(x) and CD65s Ags on PMN from these individuals. The significance of the mutation was supported by transfection of BJAB cells.     

A missense mutation (His42Arg) in the T-protein gene from a large Israeli-Arab kindred with nonketotic hyperglycinemia

Nonketotic hyperglycinemia (NKH) is caused by a mutation in the genes encoding the components of the glycine cleavage multi-enzyme system. More than 80% of the patients have defects in the gene encoding P-protein, whereas the rest of the patints have defects in the gene encoding T-protein. We have found a large Israeli-Arab kindred with NKH. At least 14 children were affected, and all the patients had seizures and respiratory failure within 2 days after birth. Enzymatic analysis revealed that T-protein activity was deficient in the liver specimen from one propositus. We screened this family for a mutation in the protein-coding region and exon/intron boundaries of T-protein gene by direct sequencing analysis. A missense mutation was found in exon 2; this resulted in an amino acid substitution from histidine to arginine at position 42 (H42R). Histidine 42 is conserved in human, bovine, chicken, pea, and Escherichia coli, suggesting that it has an important role in catalytic functions. Genotype analyses of 26 family members confirmed that the homozygous H42R mutation was completely associated with the onset of NKH. The availability of DNA testing facilitates the prenatal diagnosis of NKH and the identification of carriers, which is necessary for genetic counseling in the affected families. Received: 28 October 1997 / Accepted: 6 January 1998     

A missense mutation found in human lactate dehydrogenase-B (H) variant gene

A human lactate dehydrogenase-B mutant gene was isolated from a genomic DNA library constructed from a patient with unstable LDH-B (heart) subunit. The nucleotide sequences of seven protein-coding exons were determined and a single nucleotide substitution of G by A at Arg codon CGC in exon 4 was found. This mutation results in an amino-acid replacement of a conserved arginine by histidine at the residue "173," which is involved in an anion-binding site at the P-axis of LDH subunits.     

A homozygous nonsense mutation (428G-->A) in the human secretor (FUT2) gene provides resistance to symptomatic norovirus (GGII) infections

Noroviruses (formerly Norwalk-like viruses) are a major cause of acute gastroenteritis worldwide and are associated with a significant number of nosocomial and food-borne outbreaks. In this study we show that the human secretor FUT2 gene, which codes for an alpha(1,2)-fucosyltransferase synthesizing the H-type 1 antigen in saliva and mucosa, is associated with susceptibility to norovirus infections. Allelic polymorphism characterization at nucleotide 428 for symptomatic (n = 53) and asymptomatic (n = 62) individuals associated with nosocomial and sporadic norovirus outbreaks revealed that homozygous nonsense mutation (428G-->A) in FUT2 segregated with complete resistance for the disease. Of all symptomatic individuals, 49% were homozygous (SeSe) and 51% heterozygous (Sese428) secretors, and none were secretor negative (se428se428), in contrast to 20% nonsecretors (se428se428) among Swedish blood donors (n = 104) (P < 0.0002) and 29% for asymptomatic individuals associated with nosocomial outbreaks (P < 0.00001). Furthermore, saliva from secretor-positive and symptomatic patients but not from secretor-negative and asymptomatic individuals bound the norovirus strain responsible for that particular outbreak. This is the first report showing that the FUT2 nonsecretor (se428se428) genotype is associated with resistance to nosocomial and sporadic outbreaks with norovirus.     

A missense mutation Pro157 Arg in lipoprotein lipase (LPLNijmegen) resulting in loss of catalytic activity.

Here we report on the molecular defect that leads to a deficiency of lipoprotein lipase (LPL) activity in a proband of Dutch descent. Southern-blot analysis of the LPL gene from the patient did not reveal any major DNA rearrangements. Sequencing of polymerase-chain-reaction-amplified DNA revealed that the proband is a homozygote for G725C, resulting in a substitution of Pro157 for Arg. This substitution alters a restriction site for PvuII, which allowed rapid identification of the mutant allele in family members. Site-directed mutagenesis and transient expression of the mutant LPL in COS cells produced an enzymatically inactive protein, establishing the functional significance of this mutation. This naturally occurring mutation which alters the Pro157 adjacent to Asp156 of the proposed catalytic triad, indicates that this region of the protein is indeed crucial for LPL catalytic activity.     

A missense mutation in the nuclear gene coding for the mitochondrial aspartyl-tRNA synthetase suppresses a mitochondrial tRNA(Asp) mutation

The nuclear suppressor allele NSM3 in strain FF1210-6C/170-E22 (E22), which suppresses a mutation of the yeast mitochondrial tRNA^Asp gene in Saccharomyces cerevisiae, was cloned and identified. To isolate the NSM3 allele, a genomic DNA library using the vector YEp13 was constructed from strain E22. Nine YEp13 recombinant plasmids were isolated and shown to suppress the mutation in the mitochondrial tRNA^Asp gene. These nine plasmids carry a common 4.5-kb chromosomal DNA fragment which contains an open reading frame coding for yeast mitochondrial aspartyl-tRNA synthetase (AspRS) on the basis of its sequence identity to the MSD1 gene. The comparison of NSM3 DNA sequences between the suppressor and the wild-type version, cloned from the parental strain FF1210-6C/170, revealed a G to A transition that causes the replacement of amino acid serine (AGU) by an asparagine (AAU) at position 388. In experiments switching restriction fragments between the wild type and suppressor versions of the NSM3 gene, the rescue of respiratory deficiency was demonstrated only when the substitution was present in the construct. We conclude that the base substitution causes the respiratory rescue and discuss the possible mechanism as one which enhances interaction between the mutated tRNA^Asp and the suppressor version of AspRS.     

A novel hypothyroid dwarfism due to the missense mutation Arg479Cys of the thyroid peroxidase gene in the mouse

Recently, we found a novel dwarf mutation in an ICR closed colony. This mutation was governed by a single autosomal recessive gene. In novel dwarf mice, plasma levels of the thyroid hormones, T3 and T4, were reduced; however, TSH was elevated. Their thyroid glands showed a diffuse goiter exhibiting colloid deficiency and abnormal follicle epithelium. The dwarfism was improved by adding thyroid hormone in the diet. Gene mapping revealed that the dwarf mutation was closely linked to the thyroid peroxidase (Tpo) gene on chromosome 12. Sequencing of the Tpo gene of the dwarf mice demonstrated a C to T substitution at position 1508 causing an amino acid change from arginine (Arg) to cysteine (Cys) at codon 479 (Arg479Cys). Western blotting revealed that TPO protein of the dwarf mice was detected in a microsomal fraction of thyroid tissue, but peroxidase activity was not detected. These findings suggested that the dwarf mutation caused a primary congenital hypothyroidism by TPO deficiency, resulting in a defect of thyroid hormone synthesis.     

Functional consequences of a carboxyl terminal missense mutation Arg278Cys in human cardiac troponin T.

A carboxyl terminal missense mutant Arg278Cys of human cardiac troponin T that causes familial hypertrophic cardiomyopathy was expressed in Escherichia coli, purified, and exchanged into rabbit cardiac skinned muscle fibers using a troponin exchange technique. Compared to the fibers exchanged with human cardiac wild-type troponin T, the fibers exchanged with the mutant Arg278Cys developed less maximum force with a decreased cooperativity and a slightly increased Ca(2+) sensitivity, resulting in a significant elevation of sub-half-maximal force. Since intact cardiac muscle is thought to never be activated beyond the half-maximum level, the results suggest that an enhanced myofilament response to Ca(2+) may be responsible for the pathogenesis of hypertrophic cardiomyopathy associated with this mutation. The results also provide the first evidence that the carboxyl terminal region of cardiac troponin T plays an important role probably through its interaction with tropomyosin in allowing troponin complex to inhibit the muscle contraction at low Ca(2+), in agreement with the hypothesis deduced from the previous studies on fast skeletal troponin T.     

Contrasting patterns of polymorphisms at the ABO-secretor gene (FUT2) and plasma alpha(1,3)fucosyltransferase gene (FUT6) in human populations

The coding sequences ( approximately 1 kb) of FUT2 [ABO-Secretor type alpha(1,2)fucosyltransferase] and of FUT6 [plasma alpha(1,3)fucosyltransferase] were analyzed for allelic polymorphism by direct sequencing in five populations. The nucleotide diversities of FUT2 estimated from pairwise sequence differences were 0.0045, 0.0042, 0.0042, 0.0009, and 0.0008 in Africans, European-Africans, Iranians, Chinese, and Japanese, respectively. The nucleotide diversities of FUT6 were 0.0024, 0.0016, 0.0015, 0.0017, and 0.0020 in Africans, European-Africans, Iranians, Chinese, and Japanese, respectively. At FUT2, excesses in pairwise sequence differences compared to the number of polymorphic sites as indicated by a significantly positive Tajima's D were observed in European-Africans and in Iranians. The data do not fit expectations of the equilibrium neutral model with an infinite number of sites. On the other hand, Tajima's D's at FUT6 in each of the five populations and at FUT2 in Africans, Chinese, and Japanese were not significantly different from zero. F(ST) between the Asians and the others measured at FUT2 was higher than at FUT6. These results suggest that natural selection was responsible for the generation of the FUT2 polymorphism in European-Africans and in Iranians.     

A novel m.3395A>G missense mutation in the mitochondrial ND1 gene associated with the new tRNA(Ile) m.4316A>G mutation in a patient with hypertrophic cardiomyopathy and profound hearing loss

Mitochondria are essential for early cardiac development and impaired regulation of mitochondrial function was implicated in congenital heart diseases. We described a newborn girl with hypertrophic cardiomyopathy and profound hearing loss. The mtDNA mutational analysis revealed the presence of known polymorphisms associated to cardiomyopathy and/or hearing loss, and 2 novel heteroplasmic mutations: m.3395A>G (Y30C) occurring in a highly conserved aminoacid of the ND1 gene and the m.4316A>G located in the residue A54 of the tRNA(Ile) gene. These 2 novel variations were absent in 150 controls. All these variants may act synergistically and exert a cumulative negative effect on heart function to generate the cardiomyopathy.     

New data on the world distribution of paraoxonase (PON1 Gln 192 --> Arg) gene frequencies

The physiological role of human paraoxonase (PON), a serum enzyme that hydrolyzes organophosphate insecticides and nerve agents, is not clear. Of the three genes in the paraoxonase gene family, PON1 shows a polymorphism, Gln 192 --> Arg, governed by two common alleles named *Q and *R. These determine two different isoforms associated, respectively, with lower and higher activity towards paraoxon, a toxic metabolic product of the insecticide parathion. The *R allele has often been found associated with an increased risk of coronary heart disease. As human populations tend towards greater exposure to environmental changes, including changes in dietary habits and contact with insecticides or other toxic substances, health risks will change as well. In studying the prevention of these newly emerging risks, it could be important to know the distribution of the two alleles in the various world populations. In this paper we report on the genotype and allele frequencies of this polymorphism in different populations, most of which have never been examined for this polymorphism. Samples were taken from mainland Italy, Sardinia, Ethiopia, Benin, and Ecuador. The *R allele frequencies for the samples were: 0.313, 0.248, 0.408, 0.612, and 0.789, respectively. The data show a large variability in allele frequencies, and, in particular, that PON1 allele distribution depends on membership to different geographic populations.     

Identification of a single missense mutation in the adenine phosphoribosyltransferase (APRT) gene from five Icelandic patients and a British patient.

We have completely sequenced the adenine phosphoribosyltransferase (APRT) gene from each of six patients--five (I-V) from Iceland and one (VI) from Britain. Cases I and II shared a common ancestor six and seven generations ago, and cases I and V shared a common ancestor seven generations ago, but cases III and IV were unrelated to the above or to each other, over seven generations. Genomic DNA was amplified by PCR, subcloned into M13mp18, and sequenced. Genomic and PCR-amplified DNAs were also analyzed by restriction-enzyme digestion and Southern blotting. The same missense mutation was identified in all six patients. This mutation leads to the replacement of asp (GAC) by val (GTC), at amino acid position 65. The gene sequences from all patients were otherwise identical to our wild-type sequence. The homozygous nature of the mutation was confirmed by sequencing the PCR product directly. All six patients were homozygous for the 1.25-kb TaqI RFLP. The Icelandic patients were also homozygous for the 8-kb SphI RFLP, but the British patient was heterozygous at this site. These studies suggest that a founder effect is likely to be responsible for APRT deficiency in the Icelandic population. The finding of the same mutation in a patient from Britain suggests that this mutation may have originated in mainland Europe.     

A missense mutation (c.1963A<G) of the complementary component 2 (C2) gene is associated with serum Ca++ concentrations in pigs

Serum Ca(++) levels play important roles in the humoral immunity. The aim of this study was to detect quantitative trait loci and the associated positional candidate genes affecting baseline serum Ca(++) concentrations. A genome-wide association study was conducted in an F(2) intercross population between Landrace and Korean native pigs using the porcine single nucleotide polymorphism (SNP) 60?K beadchip and the PLINK program based on linear regression. Data used in the study included 410 F(2) pigs. All experimental animals were genotyped with 36,613 SNP markers located throughout the pig autosomes. We identified a strong association between a SNP marker on chromosome 7 and serum Ca(++) levels (DIAS0002191, genomic control-corrected P?=?7.7?×?10(-5)). The position of DIAS0002191 was closely located to SLA class III region containing the C2 gene encoding the complementary component 2 protein, a protein which is important in the humoral immune responses. De novo sequencing of the porcine C2 gene revealed a missense mutation [c.1963A相似文献   

Identification of bound water molecules in the cyclic tetrasaccharide, cyclo-{-->6}-alpha-d-Glcp-(1-->3)-alpha-D-Glcp-(1-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->)

A structural characterization of bound water molecules in the cyclic tetrasaccharide, cyclo-{-->6}-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->), was carried out by NMR spectroscopy. H-1', 2'-OH, H-3', and 4'-OH of the 3-O-glycosylated residue and H-1 of the 6-O-glycosylated residue were found to cross-relax with protons of bound waters using the double-pulsed field-gradient spin-echo ROESY experiment. In the crystal structure, one water molecule is located in the center of the plate, and its temperature factor is very low, indicating that this water molecule is an intrinsic component.     

Five novel missense mutations of the Lewis gene (FUT3) in African (Xhosa) and Caucasian populations in South Africa

Five novel missense mutations, viz., C304 A, T370 G, G484 A, G667 A, and G808 A, in the Lewis gene (FUT3) were detected in African (Xhosa) and Caucasian individuals in South Africa. These single base substitutions may result in changes in amino acid residues from Gln102 to Lys in the 304 mutation, Ser124 to Ala in the 370 mutation, Asp162 to Asn in the 484 mutation, Gly223 to Arg in the 667 mutation, and Val270 to Met in the 808 mutation. Out of the five novel mutations identified in this investigation, four new alleles (le ^484,667 , le ^484,667,808 , Le ³⁰⁴ , and Le ³⁷⁰ ) were determined in the Xhosa population and two new alleles (le ^202,314,484 and Le ³⁰⁴ ) in the Caucasian population. The determination of α(1,3/1,4)fucosyltransferase activity, after transfection of plasmids containing the new alleles into COS7 cells, suggested that alleles le ^484,667 and le ^484,667,808 encoded an inactive enzyme, and that alleles Le ³⁰⁴ and Le ³⁷⁰ encoded a functional enzyme. In addition, we also examined the incidence of five common alleles, Le ⁵⁹ , le ^59,508 , le ^59,1067 , le ^202,314 , and le ¹⁰⁶⁷ in two populations by the polymerase chain reaction/restriction fragment length polymorphism method and compared differences in the allele frequencies of FUT3 among three ethnic groups (Orientals, Africans, and Caucasians). Received: 19 January 1998 / Accepted: 4 Febraury 1998     

A missense mutation (p.G274R) in gene <Emphasis Type="Italic">ASPA</Emphasis> causes Canavan disease in a Pakistani family

Canavan disease (OMIM 271900) is an autosomal recessive lethal neurodegenerative disorder characterized by spongy degeneration of the brain. A highly consanguineous Pakistani family with Canavan disease was enrolled on the basis of diagnosis. All the affected individuals have mental retardation, megalocephaly and degradation of motor skills, poor head control, partial vision loss, weakness of the muscles and raised urinary concentration of N-acetyl aspartic acid in the urine. Blood samples were collected from affected as well as normal siblings and processed for DNA purification. Linkage analysis was performed by typing three short tandem repeat markers D17S1583 (7.19 cM), D17S1828 (10.02 cM) and D17S919 (14.69 cM) for an already-reported gene/locus ASPA at chromosome 17p13.2 causing Canavan disease. During linkage analysis, all the affected individuals were homozygous for short tandem repeat markers while the normal siblings were heterozygous showing co-segregation of the disease. Gene ASPA (NM_000049) was undertaken to sequence for mutation analysis. As a result of sequence analysis, we found missense substitution 740A→G (p.G274R) in exon 6 of gene ASPA. To our knowledge, this is the first report about Canavan disease on a Pakistani family.     

A/G Gln20Arg (exon 1) and G/A Val156Met (exon 5) polymorphisms of the human orosomucoid 1 gene in Mexico

The human orosomucoid 1 gene (ORM1) codes an alpha-1-acid glycoprotein that has been classified as an acute-phase reactive protein, and a major drug-binding serum component, as well as an immunomodulatory protein with genetic polymorphisms. Evaluation of ORM variation through isoelectric focusing and immunobloting has revealed a world-wide distribution of the ORM1 F and ORM1 S alleles. We evaluated and examined the genetic characteristics of two Mexican populations that have different anthropological and cultural antecedents, examining two ORM1 genotypes (exon 1 - A/G (Gln20Arg) and exon 5 G/A (Val156Met)) in 145 individuals, using nested polymerase chain reaction, sequencing, and restricted fragment length polymorphism. Mexican Mestizos had higher frequencies of the exon 1 A allele (P = 0.020) and AA genotype (P = 0.018) and lower frequency of the G allele (P = 0.020) when compared to Teenek Amerindians. When we examined exon 5 G/A (Val156Met) polymorphisms, we found significantly higher frequencies of the G allele (P = 0.0007) and the GG genotype (P = 0.0003) in the Mexican Mestizo population. The Teenek population had a significantly higher frequency of the A allele than has been reported for Chinese and African (P < 0.05) populations, and the G/A genotype was more frequently found in this Mexican population than in Chinese, African and European populations (P < 0.05).     

Lecithin-cholesterol acyltransferase (LCAT) deficiency with a missense mutation in exon 6 of the LCAT gene

The plasma enzyme, human lecithin-cholesterol acyltransferase (LCAT) is responsible for the majority of cholesterol ester formation in human plasma and is a key enzyme of the reverse transport of cholesterol from peripheral tissue to the liver. We sequenced genomic DNA of the LCAT gene from a Japanese male patient who was clinically and biochemically diagnosed as a familial LCAT deficiency. Analysis of all exons and exon-intron boundaries revealed only a single G to A transition within the sixth exon of both allele of the gene, leading to the substitution of methionine for isoleucinle at residue 293 of the mature enzyme. This mutation creates a new hexanucleotide recognition site for the restriction endonuclease Ndel. Familial study of Ndel digestion of the genomic DNA and determination of plasma LCAT activity established that the patient and his sister whose plasma LCAT activity were extremely reduced were homozygous and his children whose plasma LCAT activity were about half of normal controls were heterozygous for this mutation.     

A novel homozygous missense mutation in the protein C (PROC) gene causing recurrent venous thrombosis

Summary A novel homozygous CCCCTC (Pro 247 Leu) substitution was detected in the protein C genes of a patient, born to consanguineous parents, with inherited type 1 protein C deficiency and recurrent venous thrombosis. Since one of four heterozygous relatives was also clinically affected, the condition appears to be inherited as an incompletely recessive trait in this family.