... BY DALLAS M. SWALLOW, DC STOKES,* G. CORNEY AND HARRY HARRIS MRC Human Biochemical Genetics Unit, The Galton Laboratory, University College ... point at about pH 5, B with isoelectric point at about pH 7) and ion-exchange... more
... BY DALLAS M. SWALLOW, DC STOKES,* G. CORNEY AND HARRY HARRIS MRC Human Biochemical Genetics Unit, The Galton Laboratory, University College ... point at about pH 5, B with isoelectric point at about pH 7) and ion-exchange chromatography (Robinson & Stirling ...
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A genetic polymorphism is responsible for determining that some humans express lactase at high levels throughout their lives and are thus lactose tolerant, while others lose lactase expression during childhood and are lactose intolerant.... more
A genetic polymorphism is responsible for determining that some humans express lactase at high levels throughout their lives and are thus lactose tolerant, while others lose lactase expression during childhood and are lactose intolerant. We have previously shown that this polymorphism is controlled by an element or elements which act in cis to the lactase gene. We have also reported that 7 polymorphisms in the lactase gene are highly associated and lead to only 3 common haplotypes (A, B and C) in individuals of European extraction. Here we report the frequencies of these polymorphisms in Caucasians from north and south Europe and also from the Indian sub-continent, and show that the alleles differ in frequency, the B and C haplotypes being much more common in southern Europe and India. Allelic association studies with lactase persistence and non-persistence phenotypes show suggestive evidence of association of lactase persistence with certain alleles. This association was rather more clear in the analysis of small families, where haplotypes could be determined. Furthermore haplotype and RNA transcript analysis of 11 unrelated lactase persistent individuals shows that the persistence (highly expressed) allele is almost always on the A haplotype background. Non-persistence is found on a variety of haplotypes including A. Thus it appears that lactase persistence arose more recently than the DNA marker polymorphisms used here to define the main Caucasian haplotypes, possibly as a single mutation on the A haplotype background. The high frequency of the A haplotype in northern Europeans is consistent with the high frequency of lactase persistence.
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In most people worldwide intestinal lactase expression declines in childhood. In many others, particularly in Europeans, lactase expression persists into adult life. The lactase persistence phenotype is in Europe associated with the... more
In most people worldwide intestinal lactase expression declines in childhood. In many others, particularly in Europeans, lactase expression persists into adult life. The lactase persistence phenotype is in Europe associated with the -13910*T single nucleotide variant located 13,910 bp upstream the lactase gene in an enhancer region that affects lactase promoter activity. This variant falls in an Oct-1 binding site and shows greater Oct-1 binding than the ancestral variant and increases enhancer activity. Several other variants have been identified very close to the -13910 position, which are associated with lactase persistence in the Middle East and Africa. One of them, the -14010*C, is associated with lactase persistence in Africa. Here we show by deletion analysis that the -14010 position is located in a 144 bp region that reduces the enhancer activity. In transfections the -14010*C allele shows a stronger enhancer effect than the ancestral -4010*G allele. Binding sites for Oct-1 and HNF1α surrounding the -14010 position were identified by gel shift assays, which indicated that -14010*C has greater binding affinity to Oct-1 than -14010*G.
Research Interests: Genetics, Human Genetics, Complementary and Alternative Medicine, Biology, Transcription Factors, and 14 moreMedicine, Humans, Lactose intolerance, Caco-2 cells, Adult, Genetic Polymorphism, Enhancer, Binding Site, DNA-footprinting, Nucleotides, Binding affinity, alleles, binding sites, and Paediatrics and reproductive medicine
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The highly heterogeneous epithelial mucins show considerable inter-individual variability attributable to allelic variations in their tandem repeat (TR) peptide domains. Most mucins are known to show variations in repeat number but... more
The highly heterogeneous epithelial mucins show considerable inter-individual variability attributable to allelic variations in their tandem repeat (TR) peptide domains. Most mucins are known to show variations in repeat number but variation in the sequence of the individual TRs is not as well characterised. Here, we have studied variation in the immunodominant PDTR motif in the TR domain of the membrane-associated "cancer" mucin MUC1 by using the Minisatellite Variant Repeat-Polymerase chain reaction (MVR-PCR) technique. We have fully or partially mapped two nucleotide changes that encode two amino-acid changes, PDTR to PESR, across the arrays of 149 alleles. A total of 103 different maps was obtained when these changes alone were considered and additional variations were also observed. Most maps showed blocks of PDTR repeats interspersed with PESR repeats, although these were possibly more irregular in the longer alleles that also tended to have more PESR repeats. This variability has potential functional consequences and possible implications for some individuals with respect to the efficacy of immune targetting and immune therapy.
Research Interests: Genetics, Human Genetics, Complementary and Alternative Medicine, Biology, Medicine, and 15 moreHumans, Polymerase Chain Reaction, Mucin, Potential Function, Single Nucleotide Polymorphism, Genetic variation, Amino Acid Profile, Minisatellite, Amino Acid Sequence, Base Sequence, Allele, Nucleotides, Molecular Sequence Data, MUC, and Paediatrics and reproductive medicine
Lactase activity is present at high levels in the small intestine of some human adults and not others. This is due to a genetically determined polymorphism which affects the developmental regulation of the expression of the lactase gene.... more
Lactase activity is present at high levels in the small intestine of some human adults and not others. This is due to a genetically determined polymorphism which affects the developmental regulation of the expression of the lactase gene. This polymorphism is of considerable interest in relation to cultural differences in nutrition but despite exhaustive studies, the molecular basis has not yet been found. It has not even been shown whether the sequence differences reside within or adjacent to the lactase gene itself or in a trans-acting factor. We have therefore exploited known DNA 'marker' polymorphisms within the exons of the lactase gene to examine the expression of the individual lactase mRNA transcripts from persistent and non-persistent individuals in order to determine whether the regulation is in cis or trans. Our results show that in certain lactase persistent individuals one allele of the lactase gene is expressed at much lower levels than the other and these individuals tend to have intermediate lactase activities. It is proposed that these people are heterozygous for the lactase persistence and non-persistence alleles and that this means that the nucleotide substitutions responsible for the lactase persistence/non-persistence polymorphism are cis-acting. This narrows down considerably the area of the genome that needs to be searched for the relevant sequence differences.
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The production of a monoclonal antibody which detects the low-incidence red cell antigen Wra is described. The antibody (BGU1-WR) was isolated following immunization of BALB/tk mice with Wr(a+) cells. BGU1-WR is an IgG1 antibody and... more
The production of a monoclonal antibody which detects the low-incidence red cell antigen Wra is described. The antibody (BGU1-WR) was isolated following immunization of BALB/tk mice with Wr(a+) cells. BGU1-WR is an IgG1 antibody and reacted in a manner similar to human polyclonal anti-Wra with untreated, protease treated and chemically modified Wr(a+) cells.
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Intolerance of dietary carbohydrate and sugars can result from a variety of genetically determined enzyme and transporter deficiencies. This article reviews this topic and discusses in more detail the current state of our own research on... more
Intolerance of dietary carbohydrate and sugars can result from a variety of genetically determined enzyme and transporter deficiencies. This article reviews this topic and discusses in more detail the current state of our own research on lactase.
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SummaryTwo distinct isozymes (UMPH‐1 and UMPH‐2) which hydrolyse pyrimidine 5′‐nucleotides have been identified in mouse, rat and Chinese hamster tissues. One of these, UMPH‐1 appears to be specific for pyrimidine 5′‐nucleotides, whereas... more
SummaryTwo distinct isozymes (UMPH‐1 and UMPH‐2) which hydrolyse pyrimidine 5′‐nucleotides have been identified in mouse, rat and Chinese hamster tissues. One of these, UMPH‐1 appears to be specific for pyrimidine 5′‐nucleotides, whereas the other, UMPH‐2 has a broader substrate specificity. UMPH‐1 and UMPH‐2 show differences in their expression in different tissues. The evidence suggests that UMPH‐1 and UMPH‐2 are coded by distinct structural gene loci, UMPH‐1 and UMPH‐2. These isozymes have not been identified in man, and it is suggested that they may have overlapping electrophoretic mobility.
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Adult-type hypolactasia is a genetically determined inability to digest lactose after weaning. Two single-nucleotide polymorphisms (C-13910T, G-22018A) located upstream of the lactase gene (LCT) within the gene MCM6 are associated with... more
Adult-type hypolactasia is a genetically determined inability to digest lactose after weaning. Two single-nucleotide polymorphisms (C-13910T, G-22018A) located upstream of the lactase gene (LCT) within the gene MCM6 are associated with the lactase persistence/non-persistence trait in patients of European descent. Therefore, the genotyping of these SNPs has been established as a diagnostic tool for adult-type hypolactasia. We have recently shown that several novel allelic variants located in close proximity to the C-13910T SNP interfere with the diagnostic accuracy of real-time PCR-based genotyping methods. We describe here the validation of a comprehensive reverse-hybridization teststrip-based assay for the detection of common and novel LCT SNPs (C-13907G, C-13910T, T-13913C, G-13914A, T-13915G, and G-22018A). This assay is based on multiplex DNA amplification and ready-to-use membrane teststrips containing variant-specific oligonucleotide probes immobilized as an array of parallel lines. We evaluated the novel reverse-hybridization StripAssay on 125 DNA samples in comparison to LightCycler analysis and sequencing. The outcome of StripAssay genotyping was found to be completely concordant with that obtained by sequencing. The StripAssay represents an accurate and robust screening tool to identify multiple LCT/MCM6 variants in a rapid manner. It overcomes diagnostic pitfalls that were reported and allows the simultaneous genotyping of closely spaced LCT variant sites in a single-step diagnostic approach.
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In an attempt to estimate allele frequencies of lactase persistence in adult British natives, sucrase was assayed simultaneously with lactase under conditions that gave optimal activities for both enzymes. A trimodal distribution in the... more
In an attempt to estimate allele frequencies of lactase persistence in adult British natives, sucrase was assayed simultaneously with lactase under conditions that gave optimal activities for both enzymes. A trimodal distribution in the ratios of enzyme activities was demonstrated. Circumstantial evidence and statistical analyses suggest that the trimodal distribution is due to the different levels of lactase activity in the three genotypes--homozygous persistent, heterozygous, and homozygous nonpersistent, and that it is possible to correct for "nongenetic" variation by using sucrase as an internal standard. The allele frequency for lactase persistence was estimated to be .747. The implications of our findings on the genetic mechanisms involved in lactase persistence are discussed.
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Research Interests: Genetics, Biology, Cell Cycle, DNA replication, Persistence, and 15 moreMedicine, Gene expression, Humans, Polymerase Chain Reaction, Expression, Gene, Initiation, Molecular cloning, Adult, Element, Amino Acid Sequence, Cell Cycle Proteins, Cell Division Cycle, Biochemistry and cell biology, and Molecular Sequence Data
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Research Interests: Endocrinology, Medicine, Biopsy, Transport, Identification, and 15 moreHumans, Internal Medicine, Intestinal Mucosa, Alpha-Glucosidase, Female, Male, Infant, Dyspepsia, Pediatric, Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis, Isoenzymes, Duodenum, maltase, reverse transcriptase polymerase chain reaction, and Medical and Health Sciences
The enzyme lactase, which is responsible for the digestion of dietary lactose, is present in the intestine of some adults but not others. As a means of providing a platform to explore the molecular basis of this nutritionally relevant... more
The enzyme lactase, which is responsible for the digestion of dietary lactose, is present in the intestine of some adults but not others. As a means of providing a platform to explore the molecular basis of this nutritionally relevant genetic variation we have screened for polymorphism in several regions of the lactase gene. In each case simple polymerase chain reaction-based procedures (including single-strand conformation analysis and denaturing gradient gel electrophoresis) were used, combined with silver staining as a method of detection. Allelic variation was found at 6 different sites. One previously published polymorphism was also tested. The frequencies of the alleles were determined in more than 100 unrelated individuals of the Centre d’Etude du Polymorphisme Humain (CEPH) panel, and the haplotypes were deduced. A region of linkage disequilibrium was observed, which spans the whole coding region of the lactase gene (∼ 60–70 kb); there were only 3 common haplotypes in this population. When the CEPH sample was subdivided according to the population of origin (France or Utah) the haplotype frequencies were shown to be markedly different.
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SummaryThe gene coding for the GM2 activator protein has been mapped to human chromosome 5, using an enzyme‐linked immunoadsorbant assay (ELISA) to identify the human protein in human‐mouse somatic cell hybrids.
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SummaryThe gene coding for the liver/bone/kidney isozyme of alkaline phosphatase, ALPL, has been mapped to human chromosome 1 using a monoclonal antibody TRA‐2–54/2J and electrophoretic analysis to distinguish between the human and rodent... more
SummaryThe gene coding for the liver/bone/kidney isozyme of alkaline phosphatase, ALPL, has been mapped to human chromosome 1 using a monoclonal antibody TRA‐2–54/2J and electrophoretic analysis to distinguish between the human and rodent isozymes in human/rodent somatic cell hybrids.
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ABSTRACT
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... Catherine Janet Ellen Ingram,; Dallas Mary Swallow. Published Online: 21 DEC 2007. ... One particular combination of alleles designated the 'A' haplotype is particularly common in Northern Europe and is found to... more
... Catherine Janet Ellen Ingram,; Dallas Mary Swallow. Published Online: 21 DEC 2007. ... One particular combination of alleles designated the 'A' haplotype is particularly common in Northern Europe and is found to associate with lactase persistence (Poulter et al., 2003). ...
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SummaryObserrations have been made on two brothers who had progressive ataxia, intention myoclonus and visual failure starting early in the third decade of life. Their parents were consanguineous. The brothers showed bilateral cherry red... more
SummaryObserrations have been made on two brothers who had progressive ataxia, intention myoclonus and visual failure starting early in the third decade of life. Their parents were consanguineous. The brothers showed bilateral cherry red spots a t the maculae and bilateral perinuclear cataracts; their intelligence was preserved. Urine was found to contain large amounts of sialylated oligosaccharides; cultured skin fibroblasts showed deficiency of the enzyme sialidase (neuraminidase).Studies on leiirocytes and cultured skin fibroblasts showed aberrant electrophoretic mobilities of six enzmyes all of which are known to be glycoproteins, and this has been attributed to excessive amounts of sialic acid on the enzyme molecules.The clinical features together with the biochemical findings indicate that these are further cases of the newly described condition Sialidosis Type 1 and i t is suggested that the electrophoretic findings might be typical of the condition.
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SUMMARYThe lysosomal enzymes N‐acetyl hexosaminidase, α‐galactosidase and α‐mannosidase vary in electrophoretic mobility in different human lymphoblastoid (lymphoid) lines. The relative mobilities of these three enzymes and three out of... more
SUMMARYThe lysosomal enzymes N‐acetyl hexosaminidase, α‐galactosidase and α‐mannosidase vary in electrophoretic mobility in different human lymphoblastoid (lymphoid) lines. The relative mobilities of these three enzymes and three out of four other lysosomal enzymes tested correlate well with each other. The patterns appear to be relatively stable characteristics of each line. The lines RAJI and DAUDI show a strikingly fast electrophoretic mobility for all of these enzymes. N‐acetyl hexosaminidase is also markedly deficient in DAUDI.
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The human red cell acid phosphatase (ACP1) locus was assigned to region 2p23 leads to 2pter by Ferguson-Smith et al [3], more specifically to 2p23 by Hamerton et al [5]. We describe two unrelated patients with deletion of chromosome 2,... more
The human red cell acid phosphatase (ACP1) locus was assigned to region 2p23 leads to 2pter by Ferguson-Smith et al [3], more specifically to 2p23 by Hamerton et al [5]. We describe two unrelated patients with deletion of chromosome 2, with similar breakpoints in the distal portion of band p23 (del(2) (p23)). ACP1 typing in both patients revealed heterozygous BA phenotypes. Thus, we assign the locus for ACP1 to the distal portion of 2p23.
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Electrophoretic and quantitative analysis of pyrimidine 5'-nucleotidase in human erythrocytes from healthy individuals and a patient deficient in pyrimidine 5'-nucleotidase, using a range of substrates, has... more
Electrophoretic and quantitative analysis of pyrimidine 5'-nucleotidase in human erythrocytes from healthy individuals and a patient deficient in pyrimidine 5'-nucleotidase, using a range of substrates, has shown that the patient has a marked deficiency with UMP, CMP and dCMP as substrates but near normal levels of activity with dUMP and dTMP as substrates. The observations suggest that two separate structural gene loci coding for distinct 5'-nucleotidases with similar electrophoretic mobility exist in man. The genetic determination of these enzymes seems therefore to be homologous with that found in rodents.