RESUMEN
Predicting adverse pregnancy outcome in low risk patients in a community with poor socio-economic circumstances is difficult, yet about 5% of these pregnancies will result in preterm labour or severe pre-eclampsia. In this study we aimed to identify markers in pro- and anti-inflammatory genes that may contribute to disease and possibly disease prediction in a low risk community setting. A prospective study was undertaken on 450 consecutive low risk primigravid patients. Blood obtained at first booking was screened for known immunological gene variants (IL4 -590, IL1B +3953, IL1RN, IL10 -1082; -819; -592 and TNFA -308; -238; +488) as well as for novel variants in the LGALS13 gene coding for placental protein 13 (PP13). The incidence of preterm labour and pre-eclampsia was 7.1% and 6.8% respectively. A novel exonic variant (221delT) in the LGALS13 gene increased the risk for preterm labour in the total study group (relative risk RR 2.27). Maternal carriage of the interleukin-1 RN*2 allele was associated with an increased risk of hypertension in pregnancy in the Coloured subgroup of the study cohort (RR 2.53). There was an increased risk for preterm labour in the same subgroup with carriage of the TNFA -308 A-allele (TNF2) (RR 2.53). No significance was found for the other variants examined. We conclude that single nucleotide polymorphisms (SNPs) in certain genes regulating implantation and inflammation may contribute to the complex etiology of pre-eclampsia and preterm labour. The association between the 221delT deletion and adverse pregnancy outcome needs to be confirmed in different populations.
Asunto(s)
Citocinas/genética , Exones , Galectinas/genética , Proteína Antagonista del Receptor de Interleucina 1/genética , Trabajo de Parto Prematuro/genética , Polimorfismo Genético , Preeclampsia/genética , Proteínas Gestacionales/genética , Adolescente , Adulto , Citocinas/inmunología , Citocinas/metabolismo , Análisis Mutacional de ADN , Femenino , Galectinas/metabolismo , Estudios de Asociación Genética , Marcadores Genéticos/genética , Humanos , Incidencia , Proteína Antagonista del Receptor de Interleucina 1/metabolismo , Trabajo de Parto Prematuro/epidemiología , Trabajo de Parto Prematuro/inmunología , Preeclampsia/epidemiología , Preeclampsia/inmunología , Embarazo , Proteínas Gestacionales/metabolismo , Estudios Prospectivos , Factores de Riesgo , SudáfricaRESUMEN
Understanding the mechanisms of disease responsible for the syndrome of preeclampsia as well as early risk assessment is still a major challenge. The concentrations of circulating proteins in maternal blood such as placental growth factor, soluble vascular endothelial growth factor receptor-1 and soluble endoglin are altered weeks before the onset of clinical symptoms of the syndrome. Recently, other proteins in maternal serum, such as activin A, inhibin A, PAPP-A, and PP13 have been suggested to be of value in first trimester risk assessment. Since preeclampsia is a syndrome, it seems unlikely that a single test will predict all forms of preeclampsia. This realization has led to the formulation of a new conceptual framework suggesting that a combination of markers (biochemical and/or biophysical) may be required to conduct comprehensive risk assessment for the syndrome.
Asunto(s)
Biomarcadores , Marcadores Genéticos , Preeclampsia/diagnóstico , Preeclampsia/epidemiología , Educación , Femenino , Humanos , Preeclampsia/genética , Valor Predictivo de las Pruebas , Embarazo , Factores de RiesgoRESUMEN
Oxidative stress is thought to play an important role in the pathophysiology of pre-eclampsia. A defect in certain enzymes responsible for detoxification may cause prolonged exposure to reactive by-products and contribute to maternal endothelial as well as placental damage. Two polymorphisms affecting the function of the biotransformation enzymes epoxide hydrolase and glutathione S-transferase P1 were shown previously to be associated with pre-eclampsia in a Dutch population. The aim of this study was to determine if these two polymorphisms (maternal or fetal) contribute to pre-eclampsia in an anthropologically distinct population (the Western Cape region of South Africa) with a high incidence of the disease. Genomic DNA of mother - infant pairs with severe pre-eclampsia (n = 144), a population control group (n = 156) and control mother - infant pairs with uncomplicated pregnancy outcome (n = 45) were analysed for the EPHX and GSTP1 polymorphisms by polymerase chain reaction amplification and restriction enzyme digestion. Each polymorphism had a similar distribution in case and control subjects (mother and infant). The Val105/Val105 genotype of GSTP1 occurred at a higher frequency than reported for other populations. Neither maternal nor fetal EPHX Tyr113His and GSTP1 Ile105Val polymorphisms appear to contribute significantly to the pathophysiology of pre-eclampsia in the Coloured population of the Western Cape region of South Africa.
Asunto(s)
Epóxido Hidrolasas/genética , Feto/enzimología , Glutatión Transferasa/genética , Polimorfismo de Nucleótido Simple/genética , Preeclampsia/genética , Alelos , Población Negra/genética , ADN/análisis , Exones , Femenino , Frecuencia de los Genes , Genotipo , Histidina , Humanos , Embarazo , SudáfricaRESUMEN
In this report on the outcome of the first prenatal diagnosis performed for familial hypercholesterolemia (FH) in a South African family, we aim to demonstrate the value of a population-directed screening strategy to identify FH patients in populations with an enrichment for certain low-density lipoprotein receptor (LDLR) gene mutations. Prenatal diagnosis was offered to an Afrikaner couple, both partners heterozygous for the FH mutation D206E, whose first child was diagnosed with heterozygous FH and the second with homozygous FH. Genomic DNA isolated from parental peripheral blood and subsequently amniotic fluid was amplified by the polymerase chain reaction (PCR) and subjected to mutation analysis. Heterozygosity for mutation D206E was confirmed in both parents, whilst this mutation was not detected in DNA directly amplified from amniotic fluid. To exclude the possibility of a false-negative result due to the limited number of cells in the uncultured amniotic fluid sample, cells were also cultured in vitro, and the DNA extracted and subjected to a second round of analysis. This confirmed the absence of mutation D206E in the fetus. This case illustrates the application of a DNA-based mutation detection technique as a simple and rapid diagnostic aid that can be carried out at a relatively early gestational stage. Prenatal diagnosis of FH, aimed at the detection of homozygous cases, is particularly feasible in populations and families with molecularly defined LDLR gene mutations.
Asunto(s)
ADN/genética , Hiperlipoproteinemia Tipo II/diagnóstico , Diagnóstico Prenatal , Adulto , Secuencia de Bases , Cartilla de ADN , Femenino , Efecto Fundador , Heterocigoto , Humanos , Hiperlipoproteinemia Tipo II/epidemiología , Hiperlipoproteinemia Tipo II/genética , Masculino , Mutación , Linaje , Reacción en Cadena de la Polimerasa , Receptores de LDL/genética , Factores de Riesgo , Sudáfrica/epidemiologíaRESUMEN
OBJECTIVE: This study was undertaken to investigate the involvement of MTHFR gene mutations C677T and A1298C implicated in vascular disease, in patients with abruptio placentae and intrauterine growth restriction (IUGR). STUDY DESIGN: DNA was extracted from blood samples of 54 patients with placental vasculopathy (18 patients with abruptio placentae and 36 with IUGR) and 114 control patients and amplified by the polymerase chain reaction (PCR). The resulting fragments were subjected to restriction enzyme analysis and resolved by gel electrophoresis. RESULTS: A significant association could be demonstrated between mutation A1298C and both abruptio placentae and IUGR. Combined heterozygosity for mutations C677T and A1298C was detected in 22.2% of abruptio placentae cases. CONCLUSIONS: Combined heterozygosity for MTHFR mutations C677T and A1298C may represent a genetic marker for abruptio placentae.
Asunto(s)
Desprendimiento Prematuro de la Placenta/genética , Retardo del Crecimiento Fetal/genética , Heterocigoto , Mutación , Oxidorreductasas actuantes sobre Donantes de Grupo CH-NH/genética , Análisis Mutacional de ADN , Femenino , Frecuencia de los Genes , Humanos , Metilenotetrahidrofolato Reductasa (NADPH2) , Placenta/irrigación sanguínea , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Embarazo , Enfermedades Vasculares/genéticaRESUMEN
OBJECTIVE: A raised plasma level of lipoprotein(a) (Lp(a)) is an established genetic risk factor for coronary heart disease (CHD), particularly in patients with concomitant elevation of low-density lipoprotein (LDL) cholesterol. The current study focused on the comparison of two commercially available Lp(a) assay kits to determine whether differences observed in measured Lp(a) levels could be deemed negligible in CHD risk assessment in familial hypercholesterolaemic (FH) patients. DESIGN: To compare results obtained on duplicate plasma samples using two commercially available Lp(a) measuring kits, the immunoradiometric assay (RIA) and the enzyme-linked immunoabsorbent assay (ELISA). SETTING: Division of Human Genetics, Department of Obstetrics and Gynaecology, University of Stellenbosch, Tygerberg, South Africa and the Institute for Medical Biology and Human Genetics, University of Innsbruck, Austria. SUBJECTS: Plasma samples were obtained from 146 family members of 65 molecularly characterised South African FH families for comparative analysis. RESULTS: Using the RIA method, 34 samples (23%) considered to be in the normal range by the ELISA technique, were placed in the high-risk group (> 30 mg/dl). Only one sample, considered to have a normal Lp(a) level with the RIA method, was categorised by the ELISA technique as high risk. CONCLUSION: Our data demonstrate that measurements of Lp(a) using the RIA method (the only assay available in South Africa at the time of this study) differ significantly from those obtained by the reference ELISA technique, suggesting that misclassification could lead to inaccurate CHD risk assessment. This is an important consideration in Afrikaner FH families, where plasma levels of Lp(a) have been shown to be elevated significantly in FH patients compared with non-FH individuals.
Asunto(s)
Enfermedad Coronaria/genética , Predisposición Genética a la Enfermedad/genética , Hiperlipoproteinemia Tipo II/genética , Lipoproteína(a)/sangre , Adulto , Anciano , Enfermedad Coronaria/sangre , Enfermedad Coronaria/diagnóstico , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Hiperlipoproteinemia Tipo II/sangre , Hiperlipoproteinemia Tipo II/diagnóstico , Ensayo Inmunorradiométrico , Masculino , Persona de Mediana Edad , Juego de Reactivos para Diagnóstico , Medición de Riesgo , Sensibilidad y EspecificidadRESUMEN
The low-density lipoprotein receptor (LDLR) plays a major role in cholesterol homeostasis. Mutations in the regulatory region of the LDLR gene, although rare, have been shown to alter transcriptional activity of the gene and can cause familial hypercholesterolaemia (FH). In this study, a transition (c-->t) was identified at nucleotide position -59 within repeat 2 of the LDLR promoter in a South African FH patient of mixed ancestry. By screening 17 family members of the index case for this promoter mutation, two additional single base changes (-124c-->t and-175g-->t) were identified, located at recently described cis- acting regulatory sequences of the LDLR promoter. Both the-59c-->t and the-124c-->t transitions were identified in the normocholesterolaemic son of the index patient. Reporter plasmids containing the normal and mutant promoter fragments were constructed by directional cloning. Transcription studies using a luciferase reporter system demonstrated that the-59c-->t mutation significantly reduces promoter activity in both the presence and absence of sterols ( approximately 40% of normal activity), while the-124c-->t variant increases transcription ( approximately 160%) of the LDLR gene. The intra-familial phenotypic variability observed amongst individuals with the-59c-->t mutation can probably be ascribed to allelic interaction, suggesting that variation in the LDLR promoter region may contribute significantly to the phenotypic expression of FH-related mutations in populations where these mutations prevail.
Asunto(s)
Hiperlipoproteinemia Tipo II/genética , Mutación Puntual , Regiones Promotoras Genéticas , Receptores de LDL/genética , Transcripción Genética/genética , Adolescente , Adulto , Anciano , Alelos , Clonación Molecular , Femenino , Genes Reporteros , Humanos , Luciferasas/biosíntesis , Masculino , Persona de Mediana Edad , Linaje , Proteínas Recombinantes de Fusión/biosíntesis , SudáfricaRESUMEN
Mutation analysis was performed on DNA samples of 965 individuals from four different ethnic groups in South Africa, in an attempt to determine the spectrum of sequence variants in the haemochromatosis ( HFE ) gene. This population screening approach, utilizing a combined heteroduplex and single-strand conformation polymorphism (HEX-SSCP) method, revealed three previously described and four novel missense mutations. Novel variants V53M and V59M were identified in exon 2, Q127H in exon 3 and R330M in exon 5. The exon 5 variant was identified in one of 13 patients referred for a molecular diagnosis of hereditary haemochromatosis (HH), who tested negative for the known C282Y and H63D mutations. Mutation Q127H was detected in exon 3 of the HFE gene together with mutation H63D in an apparently severely affected patient previously shown to carry the protoporphyrinogen oxidase ( PPOX ) gene mutation R59W, which accounts for dominantly inherited variegate porphyria (VP) in >80% of affected South Africans. The mutant allele frequency of the C282Y mutation was found to be significantly lower in 73 apparently unrelated VP patients with the R59W mutation than in 102 controls drawn from the same population ( P = 0.005). The population screening approach used in this study revealed considerable genotypic variation in the HFE gene and supports previous data on the involvement of this gene in the porphyria phenotype.
Asunto(s)
Antígenos HLA/genética , Hemocromatosis/genética , Antígenos de Histocompatibilidad Clase I/genética , Proteínas de la Membrana , Porfirias/genética , Sustitución de Aminoácidos , Secuencia de Bases , Población Negra/genética , Niño , ADN/química , ADN/genética , Análisis Mutacional de ADN , Femenino , Genotipo , Hemocromatosis/etnología , Proteína de la Hemocromatosis , Análisis Heterodúplex , Humanos , Masculino , Mutación , Mutación Puntual , Polimorfismo Conformacional Retorcido-Simple , Porfirias/etnología , Sudáfrica/epidemiología , Población Blanca/genéticaRESUMEN
The South African population harbors genes that are derived from varying degrees of admixture between indigenous groups and immigrants from Europe and the East. This study represents the first direct mutation-based attempt to determine the impact of admixture from other gene pools on the familial hypercholesterolemia (FH) phenotype in the recently founded Coloured population of South Africa, a people of mixed ancestry. A cohort of 236 apparently unrelated patients with clinical features of FH was screened for a common mutation causing familial defective apolipoprotein B-100 (FDB) and seven low-density lipoprotein receptor (LDLR) gene defects known to be relatively common in South Africans with FH. Six founder-type 'South African mutations' were responsible for FH in approximately 20% of the study population, while only 1 patient tested positive for the familial defective apolipoprotein B-100 mutation R3500Q. The detection of multiple founder-type LDLR gene mutations originating from European, Indian and Jewish populations provides direct genetic evidence that Caucasoid admixture contributes significantly to the apparently high prevalence of FH in South African patients of mixed ancestry. This study contributes to our knowledge of the biological history of this unique population and illustrates the potential consequences of recent admixture in populations with different disease risks.
Asunto(s)
Efecto Fundador , Hiperlipoproteinemia Tipo II/genética , Mutación , Receptores de LDL/genética , Haplotipos , Humanos , Hiperlipoproteinemia Tipo II/epidemiología , Hiperlipoproteinemia Tipo II/etnología , Fenotipo , Prevalencia , Sudáfrica/epidemiologíaRESUMEN
The STM7 gene encodes a novel phosphatidylinositol-4-phosphate 5-kinase (PtdInsP 5-kinase) that is subject to alternative splicing and developmental control. We have recently presented data indicating that several splice variants of STM7 incorporate elements of the X25 sequence, previously implicated in the pathogenesis of Friedreich's ataxia by the detection of an intronic GAA repeat expansion as the predominant mutation in affected individuals. We now report the exon-intron structure of STM7.I and primer sequences designed to facilitate full characterization, including details relating to a novel exon (STM7; exon 17) derived from the 3'-UTR of the PRKACG gene. The detection of a mutation(s) within these exons would provide additional support for the hypothesis that a defect in phosphoinositide metabolism gives rise to the disease phenotype.
Asunto(s)
Proteínas de Unión a Hierro , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Empalme Alternativo , Secuencia de Bases , Cartilla de ADN/genética , Exones , Ataxia de Friedreich/enzimología , Ataxia de Friedreich/genética , Humanos , Intrones , Repeticiones de Minisatélite , Datos de Secuencia Molecular , Mutación , Fenotipo , Reacción en Cadena de la Polimerasa , Repeticiones de Trinucleótidos , FrataxinaRESUMEN
The STM7 gene on chromosome 9 was recently 'excluded' as a candidate for Friedreich's ataxia following the identification of an expanded intronic GAA triplet repeat in the adjacent gene, X25, in patients with the disease. Using RT-PCR, northern and sequence analyses, we now demonstrate that X25 comprises part of the STM7 gene, contributing to at least four splice variants, and report the identification of new coding sequences. Functional analysis of the STM7 recombinant protein corresponding to the reported 2.7-kilobase transcript has demonstrated PtdlnsP 5-kinase activity, supporting the idea that the disease is caused by a defect in the phosphoinositide pathway, possibly affecting vesicular trafficking or synaptic transmission.
Asunto(s)
Ataxia de Friedreich/genética , Genes/genética , Proteínas de Unión a Hierro , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Proteínas/genética , Adulto , Empalme Alternativo/genética , Secuencia de Aminoácidos , Mapeo Cromosómico , Exones/genética , Ataxia de Friedreich/enzimología , Humanos , Datos de Secuencia Molecular , Especificidad de Órganos , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Placenta , ARN Mensajero/análisis , ARN Mensajero/genética , Proteínas Recombinantes de Fusión/metabolismo , Alineación de Secuencia , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , FrataxinaRESUMEN
Neurotrophic factors are essential neurone survival promoting molecules that are often secreted and that bind to neuronal cell surface receptors. Glial cell line-derived neurotrophic factor, GDNF, is a potent neurotrophic factor that promotes the survival of dopaminergic neurones in cultures including embryonic neuronal cultures. We have mapped the gene encoding GDNF by two independent methods: using a cell hybrid panel and by fluorescent in situ hybridisation. We find GDNF lies on the short arm of human chromosome 5, at 5p13.1-p13.3 ability to promote dopamine uptake in midbrain cultures. The protein was partially sequenced and a rat GDNF cDNA was isolated by screening a B49 cDNA library with an oligonucleotide probe designed from the amino-terminus of the rat protein. Human GDNF sequences were isolated by screening a human genomic library with a portion of the rat GDNF cDNA (Lin et al. 1993). We wished to localise the GDNF gene in the human genome and determine its proximity to possible sites of mutation, particularly phenotypes affecting neuronal function.
Asunto(s)
Cromosomas Humanos Par 5 , Proteínas del Tejido Nervioso/genética , Animales , Secuencia de Bases , Mapeo Cromosómico , Cromosomas Artificiales de Levadura , Cartilla de ADN , Biblioteca Genómica , Factor Neurotrófico Derivado de la Línea Celular Glial , Humanos , Células Híbridas , Datos de Secuencia Molecular , Factores de Crecimiento Nervioso/genética , Proteínas del Tejido Nervioso/biosíntesis , Sondas de Oligonucleótidos , Reacción en Cadena de la Polimerasa/métodos , RatasRESUMEN
We have previously assigned the mutation causing Friedreich's ataxia (FRDA) to 9q13 by genetic linkage and fluorescent in situ hybridization analysis, and identified recombination events which position the gene centromeric to D9S5. We report here the extension of a yeast artificial chromosome contig to span the 860 kb interval immediately proximal to this marker, which includes the D9S886 and D9S887/888 loci reported to flank the FRDA locus, and the construction of a high resolution cosmid contig initiated from the D9S888 locus. Exon trapping and cDNA library screening strategies have resulted in the isolation of a candidate gene which traverses the centromeric boundary of the FRDA critical region. The gene spans a genomic interval greater than 220 kb with at least two of the coding exons located proximal to the D9S887/888 loci. Expression is complex, with multiple transcripts detected in a variety of tissues and evidence of alternative splicing and developmental control. The predicted amino acid sequence for the 2.7 kb transcript reported here shows a marked homology to the deduced amino acid sequence of the Saccharomyces cerevisiae MSS4 protein, proposed to function within the phosphoinositide cycle, suggesting a potential role for the human homologue in signal transduction. Whilst no evidence for mutation has been detected in this transcript, the sequence represents only one of the shorter alternatively spliced species identified by Northern analysis and direct sequencing. This gene remains a strong candidate for FRDA.
Asunto(s)
Ataxia de Friedreich/genética , Transducción de Señal/genética , Empalme Alternativo , Secuencia de Aminoácidos , Secuencia de Bases , Mapeo Cromosómico , Cromosomas Artificiales de Levadura , Cromosomas Humanos Par 9/genética , Clonación Molecular , Cósmidos , ADN Complementario/genética , Exones , Marcadores Genéticos , Humanos , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Proteínas/genética , Homología de Secuencia de AminoácidoRESUMEN
Orientation of the Friedreich's ataxia locus (FRDA) with respect to D9S15 and D9S5 has proved critical to the design of subsequent cloning strategies. The rarity of recombination events between FRDA and these markers, originally used to determine assignment to human chromosome region 9q13-->q21.1, has necessitated the instigation of physical mapping studies to determine order and, hence, the precise location of the disease gene. Simultaneous fluorescence in situ hybridisation using cosmid clones located in close proximity to the ends of a 1.2-Mb yeast artificial chromosome clone extending into the FRDA candidate region provides physical evidence for the order of the marker loci to be cen-D9S202-D9S5-D9S15-qter. The possibility that a pericentric inversion, occurring naturally in approximately 1% of the normal population, may affect the order of markers within this region has been eliminated. Considered in association with the interpretation of a recombination event detected in a single affected individual, these data indicate that the FRDA locus is located proximal to D9S5.