RESUMEN
OBJECTIVES: Dihydropyrimidine dehydrogenase (DPD) is the initial rate-limiting enzyme in endogenous pyrimidine catabolism and is responsible for the reduction of the pyrimidine analog 5-fluorouracil (5-FU). DPD deficiency is known to cause potentially lethal toxicity in patients receiving 5-FU. We here report a frequency analysis of one of the major splice-site mutations in the DPDY gene, and further two new DPYD gene variants. DESIGN AND METHODS: Restriction fragment length polymorphism (RFLP) and DNA sequence analysis were performed on genomic DNA and mRNA. RESULTS: In 400 patients that were diagnosed with cancer and were eligible for 5-FU treatment, 14 patients were found to be heterozygous for the splice-site mutation DPYD IVS14+1G>A, which corresponds to a population frequency of 3.5%. Two novel variants in the DPYD gene were identified. The first case was heterozygous for DPYD c.1796T>C (p.M599T). In the second case, we observed heterozygosity for the splice-site mutation DPYD IVS14+17A>G. CONCLUSIONS: We report two new DPYD gene variants, of which DPYD c.1796T>C is potentially pathogenic, whereas DPYD IVS14+17A>G is suggested as a variant without clinical significance.
Asunto(s)
Antimetabolitos Antineoplásicos/efectos adversos , Dihidrouracilo Deshidrogenasa (NADP)/genética , Fluorouracilo/efectos adversos , Variación Genética , Anciano , Antimetabolitos Antineoplásicos/metabolismo , Antimetabolitos Antineoplásicos/uso terapéutico , Dihidrouracilo Deshidrogenasa (NADP)/metabolismo , Femenino , Fluorouracilo/metabolismo , Fluorouracilo/uso terapéutico , Humanos , Mutación , Neoplasias/tratamiento farmacológico , Polimorfismo de Longitud del Fragmento de Restricción , Análisis de Secuencia de ADNRESUMEN
AIMS: To describe the occurrence of spinal muscular atrophy (SMA) in childhood; to evaluate if any of the genes in the SMA region on chromosome 5q13 correlates with disease severity; to make genotype-phenotype correlations; to evaluate the variability of different disease alleles in carriers and the sensitivity of multiplex ligation-dependent probe amplification (MLPA) for detecting carriers. METHODS: In a population-based study from Western Sweden MLPA was used to determine the copy-numbers of several genes in the SMA region (SMN1, SMN2, BIRC1, GTF2H2 and SERF1A) in SMA-patients and their parents. RESULTS: We estimated the incidence of SMN1-related SMA in childhood at 1 in 11 800 live births and confirmed the relationship between the number of SMN2 copies and the severity of disease. No other direct relationships were found. All but one of the analysed parents were confirmed as carriers by MLPA analysis. A total of at least 30 different disease alleles were identified and no specific disease allele represented more than 15% of the total. CONCLUSION: The childhood incidence of SMA in the Swedish population is around 1 in 12,000 live births and it is unlikely that there is any founder effect involved in SMA in western Sweden.
Asunto(s)
Cromosomas Humanos Par 5/genética , Proteínas del Complejo SMN/genética , Atrofias Musculares Espinales de la Infancia/epidemiología , Adolescente , Alelos , Niño , Preescolar , Femenino , Genotipo , Heterocigoto , Humanos , Incidencia , Lactante , Masculino , Fenotipo , Prevalencia , Atrofias Musculares Espinales de la Infancia/genética , Suecia/epidemiologíaRESUMEN
Spinal muscular atrophy (SMA) is an autosomal recessive disease caused by decreased levels of survival motor neuron protein (SMN). In the majority of cases, this decrease is due to absence of the SMN1 gene. Multiplex ligation-dependent probe amplification (MLPA) is a modern quantitative molecular method. Applied in SMA cases, it improves diagnostics by simultaneously identifying the number of copies of several target sequences in the SMN1 gene and in nearby genes. Using MLPA in clinical diagnostics, we have identified a previously unreported, partial deletion of SMN1 (exons 1-6) in two apparently unrelated Swedish families. This mutation would not have been detected by conventional diagnostic methods. This paper illustrates the broad clinical and genetic spectrum of SMA and includes reports of MLPA results and clinical descriptions of a patient with homozygous absence of SMN1 and only one SMN2 (prenatal onset SMA type 1), an asymptomatic woman with five SMN2 (lacking SMN1) and representative patients with SMA types 1, 2 and 3.
Asunto(s)
Proteína de Unión a Elemento de Respuesta al AMP Cíclico/genética , Análisis Mutacional de ADN/métodos , Biología Molecular/métodos , Atrofia Muscular Espinal/diagnóstico , Atrofia Muscular Espinal/genética , Mutación/genética , Proteínas del Tejido Nervioso/genética , Proteínas de Unión al ARN/genética , Adolescente , Adulto , Niño , Sondas de ADN/genética , Exones/genética , Femenino , Eliminación de Gen , Dosificación de Gen/genética , Predisposición Genética a la Enfermedad/genética , Genotipo , Humanos , Lactante , Recién Nacido , Patrón de Herencia/genética , Masculino , Persona de Mediana Edad , Atrofia Muscular Espinal/fisiopatología , Valor Predictivo de las Pruebas , Proteínas del Complejo SMN , Proteína 1 para la Supervivencia de la Neurona Motora , Proteína 2 para la Supervivencia de la Neurona MotoraRESUMEN
Dominant inheritance is presumed in 6-10% of breast and ovarian cancers. Mutations in BRCA1 and BRCA2 genes are the most commonly identified causative genes in such families. The frequency of mutation carriers with breast/ovarian cancer depends on the population studied, and display considerable variation that coincides with ethnic and geographical diversity. Mutation analyses were performed in 143 families registered at the Cancer Genetic Counseling Clinic of western Sweden. In a thorough mutation screening procedure, the entire BRCA1 and BRCA2 genes were analyzed using a combination of complementary mutation detection techniques. Mutations in either BRCA1 or BRCA2 were detected in 36% (52 out of 143) of all screened families. All families were clinically evaluated regarding age at diagnosis, type of cancer and number of cancer cases in the family. Among high-risk families, the mutation detection rate was 39% (46 out of 117). The detection rate observed among families with cases of ovarian cancer (42 out of 62, 68%), was substantially higher than in families with only breast cancer (10 out of 81, 12%). Age at ovarian cancer did not seem to have an effect on the detection rate. The analyses revealed 11 frameshift mutations, 4 nonsense mutations and 2 large deletions. Notably, the BRCA1 c.3171ins5 mutation accounted for 34 of 52 (65%) identified mutations. Seven mutations are novel: BRCA1c.409_410del; c.1912T>G; c.2228_2229del; c.3029delA; c.3433delA, a large deletion covering exons 1-3 of BRCA1and one BRCA2 mutation; BRCA2c.6287_6290del. We have shown that the founder mutation BRCA1 c.3171ins5 has a great influence on western Swedish breast/ovarian cancer families along with a high number of mutations unique for the region. In order to achieve a high mutation detection rate we suggest a combination of several detection techniques.
Asunto(s)
Neoplasias de la Mama/genética , Genes BRCA1 , Genes BRCA2 , Pruebas Genéticas/métodos , Mutación de Línea Germinal , Neoplasias Ováricas/genética , Adulto , Anciano , Análisis Mutacional de ADN , Femenino , Efecto Fundador , Heterocigoto , Humanos , Incidencia , Patrón de Herencia , Persona de Mediana Edad , SueciaRESUMEN
Proton-translocating mitochondrial nicotinamide nucleotide transhydrogenase (NNT) was investigated regarding its physiological role in Caenorhabditis elegans. NNT catalyzes the reduction of NADP(+) by NADH driven by the electrochemical proton gradient, Deltap, and is thus a potentially important source of mitochondrial NADPH. Mitochondrial detoxification of reactive oxygen species (ROS) by glutathione-dependent peroxidases depends on NADPH for regeneration of reduced glutathione. Transhydrogenase may therefore be directly involved in the defense against oxidative stress. nnt-1 deletion mutants of C. elegans, nnt-1(sv34), were isolated and shown to grow essentially as wild type under normal laboratory conditions, but with a strongly lowered GSH/GSSG ratio. Under conditions of oxidative stress, caused by the superoxide-generating agent methyl viologen, growth of worms lacking nnt-1 activity was severely impaired. A similar result was obtained by using RNAi. Reintroducing nnt-1 in the nnt-1(sv34) knockout mutant led to a partial rescue of growth under oxidative stress conditions. These results provide evidence for the first time that nnt-1 is important in the defense against mitochondrial oxidative stress.
Asunto(s)
Caenorhabditis elegans/genética , Mutación , NADP Transhidrogenasas/genética , Animales , Proteínas de Caenorhabditis elegans/fisiología , Proliferación Celular , Electroquímica , Eliminación de Gen , Glutatión , Proteínas Fluorescentes Verdes/metabolismo , Immunoblotting , Mitocondrias/metabolismo , Modelos Químicos , Modelos Genéticos , NADP/química , NADP Transhidrogenasas/fisiología , Estrés Oxidativo , Paraquat/farmacología , Fenotipo , Plásmidos/metabolismo , Protones , Interferencia de ARN , ARN Bicatenario/química , Factores de TiempoRESUMEN
Proton-translocating nicotinamide nucleotide transhydrogenase is located in the mitochondrial inner membrane and catalyzes the reduction of NADP(+) by NADH to NADPH and NAD(+). The present investigation describes the expression of the transhydrogenase gene in various mouse organs, subsections of the human brain and Caenorhabditis elegans. In the mouse, the expression was highest in heart tissue (100%) followed by kidney (64%), testis (52%), adrenal gland (41%), liver (35%), pancreas (34%), bladder (26%), lung (25%), ovary (21%) and brain (14%). The expression in brain tissue was further investigated in the human brain which showed a distribution that apparently varied as a function of neuronal density, a result that was supported by estimations of expression in C. elegans using Green Fluorescent Protein (GFP) controlled by the transhydrogenase promoter. GFP-expressing C. elegans lines showed a clear concentration of fluorescence to the gut, the pharyngeal-intestinal valve and certain neurons. It is concluded that the transhydrogenase gene is expressed to various extents in all cell types in mouse, human and C. elegans.