Biomedical subjects

X Estivill

Publications and source records attributed to X Estivill.

At least 199 records · Page 11Linked to original sources

PubMed1996

The effect of zidovudine on skeletal muscle mtDNA in HIV-1 infected patients with mild or no muscle dysfunction.

Zidovudine (ZDV), a nucleoside analogue which inhibits viral replication, is currently used in the treatment of type 1 human immunodeficiency virus (HIV-1) infection. It has been considered to be the cause of an acquired form of myopathy associated with a depletion of mitochondrial DNA (mtDNA) in muscle fibres, although the fact that the patients previously studied were clearly symptomatic, and the theoretical difficulty in differentiating on HIV-related myopathy from the effects of ZDV, led to a controversy on the possible deleterious effect of ZDV on muscle fibres. We studied the muscle biopsy taken from 42 HIV-1 infected patients, regardless of their medical complaints, and two series of controls: 12 HIV-negative patients suffering from diverse neuromuscular diseases and 10 normal patients who underwent orthopaedic surgery. Whole DNA was extracted following standard procedures and analysed by means of Southern blotting and polymerase chain reaction (PCR). We found that mtDNA was only depleted in HIV-1 infected patients treated with ZDV, but not in controls or patients untreated with this antiretroviral drug. Moreover, the depletion was more marked in patients who either presented weakness, myalgia, raised serum creatine kinase (CK), or ragged-red fibres. Mitochondrial DNA deletions were found in low proportion in all groups of patients, regardless of their HIV infection or ZDV status, but not in normal controls. We conclude that ZDV treatment in HIV-1 positive patients produces depletion of muscle mtDNA. The depletion can be demonstrated even in asymptotic patients, but is more marked in patients with clinical symptoms or abnormalities in their muscle biopsies. Other mtDNA abnormalities such as deletions seemed to be more related to other circumstances concurring in HIV-1 infected patients than to the effects of ZDV.

Adult↗

PubMed1996

A human homologue of Drosophila minibrain (MNB) is expressed in the neuronal regions affected in Down syndrome and maps to the critical region.

The minibrain (mnb) gene of Drosophila melanogaster encodes a serine-threonine protein kinase with an essential role in postembryonic neurogenesis. A corresponding human gene with similar function to mnb could provide important insights into both normal brain development and the abnormal brain development and mental retardation observed in many congenital disorders. Trisomy 21 or Down syndrome (DS) is the most frequent human birth defect. It is associated with mental retardation and a broad spectrum of physical abnormalities. A region on human chromosome 21 has been designated the Down syndrome critical region (DSCR) and when present in three copies, this is responsible for many of the characteristic features of DS, including mental retardation. We have isolated a human homologue of mnb from the DSCR. MNB encodes a 6.1 kb transcript which is expressed in foetal brain, lung, kidney and liver. Using a human probe, two major transcripts (6.1 and 3.1 kb) were identified in mouse and expression was detected in situ in several regions of the mouse brain, including the olfactory bulb, the cerebellum, the cerebral cortex, the pyramidal cell layer of the hippocampus and several hypothalamic nuclei. This expression pattern corresponds to the regions of the brain that are abnormal in individuals with DS and suggests that overexpression of MNB could have detrimental consequences in DS patients.

Amino Acid Sequence↗

PubMed1996

Homozygosity for R87H missense mutation and for a rare intron 7 DNA variant (7054G --> A) in the PROC genes of three siblings initially classified as heterozygotes for protein C deficiency.

We report the results of protein C gene (PROC) analysis in a Spanish family with hereditary PC deficiency characterized by the presence of three siblings with PC anticoagulant activity levels clearly below 50% of normal and PC antigen and amidolytic activities between 50 and 75% of normal. Their parents are first cousins and have PC levels between 50 and 80% of normal. Sequence analysis of the whole coding sequence of the PROC gene revealed that the three siblings are double homozygotes for a G to A transition at nucleotide 3203 that replaces arginine 87 by histidine (R87H) and for another G to A transition at nucleotide 7054, in intron 7 (7054G --> A). Both parents and one sister were found to be double heterozygotes for these two mutations. Screening for the intronic mutation in a control group and RT-PCR cDNA studies from ectopically transcribed mRNA indicated that 7054G --> A is most likely a rare but neutral DNA variant. These results and the fact that heterozygosity for the missense R87H mutation has also been found associated with a slightly decreased PC anticoagulant activity in another Spanish family, lead us to conclude that homozygosity for R87H is responsible for the PC deficient phenotype in these three siblings.

Adenine↗

PubMed1996

Aberrant RNA splicing of the protein C and protein S genes in healthy individuals.

RNA-based studies are an important tool for the identification and functional characterization of mutations underlying inherited disease. These studies could in principle be compromised by 'aberrant splicing' (the generation of alternatively spliced transcripts lacking any obvious function) during normal expression of the genes under investigation. Using a highly sensitive RT-PCR assay, we show here that aberrant splicing is a frequent occurrence during expression of the protein C (PROC) and protein S (PROS) genes. Aberrantly spliced transcripts were present in different cell types including liver, the main expressing tissue for both protein C and protein S. In an attempt to compare individual mRNA splicing patterns, PROC and PROS RNA from easily accessible cells of different healthy control individuals was studied. However, variation between different RT-PCR assays from the same individual precluded both the relative quantitation of the aberrant transcripts and the analysis of interindividual differences. Our findings are consistent with the notion that a low level of aberrantly spliced transcripts are routinely generated during PROC and PROS gene expression. The possibility that these transcripts may complicate the RT-PCR analysis of pathological transcripts must be taken into account when RNA-based strategies of disease analysis are considered.

Electrophoresis, Agar Gel↗

PubMed1996

Thirteen cystic fibrosis patients, 12 compound heterozygous and one homozygous for the missense mutation G85E: a pancreatic sufficiency/insufficiency mutation with variable clinical presentation.

To study the severity of mutation G85E, located in the first membrane spanning domain of the CFTR gene, we studied the clinical features of 13 Spanish patients with cystic fibrosis (CF) carrying this mutation. G85E accounts for about 1% of Spanish CF alleles. One patient was homozygous G85E/G85E and the rest were compound heterozygotes for G85E and other mutations (delta F508 nine patients, delta I507 two patients, and 712-1G > T one patient). The characteristics of the pooled G85E/any mutation group were compared with those of 30 delta F508 homozygotes. Mean age at diagnosis and percentage of ideal height for age were higher in the G85E/any mutation group (4.2 (SD 4.7) v 2.4 (SD 2.3), p < 0.05, and 102.8 (SD 4.7) v 97.8 (SD 4.1), p < 0.01), both probably related to the greater prevalence of pancreatic sufficiency (70% v 0%, p < 0.01). The G85E homozygote was pancreatic sufficient. Sweat sodium levels were slightly higher, and salt loss related problems more frequent, in the G85E/any group. Two of the G85E patients died of respiratory failure aged 6 and 14 years. Striking discordance in the phenotype was observed in two pairs of sibs, one of them dizygotic twins, suggesting that factors, genetic and environmental, other than CFTR genotype are important in determining CF phenotype.

Child↗

PubMed1996

Mosaicism for the fragile X syndrome full mutation and deletions within the CGG repeat of the FMR1 gene.

The main mutation responsible for the fragile X syndrome is the expansion of an untranslated CGG repeat in the first exon of the FMR1 gene, associated with the hypermethylation of the proximal CpG island and the CGG repeat region, and repression of transcription of FMR1. Fragile X syndrome mosaicism has been described as the coexistence of the full mutation and the permutation. We present here two cases of mosaicism for the full mutation in the FMR1 gene and deletions involving the CGG repeat region. In one case the deletion removed 113 bp proximal to the CGG repeat and part of the repeat itself, leaving 30 pure repeats, and representing 17% of lymphocytes of the patient. The 5' breakpoint of this deletion falls outside the putative hotspot for deletions in the CGG region of FMR1. In the second case the deleted region only involved the CGG sequence (leaving 15 pure repeats), with normal sequences flanking the repeat; this deleted ("normal") FMR1 was estimated to be in about 31% of blood lymphocytes. This second case can be considered a true regression of the CGG FMR1 expansion to a normal sized allele, although in mosaic form.

Adolescent↗

PubMed1996

Renal-hepatic-pancreatic dysplasia: an autosomal recessive malformation.

We report two brothers with a cystic malformation of the kidneys, liver, and pancreas. In both cases the malformation was fatal and the children died shortly after birth. The pathological findings, consisting of multicystic dysplastic kidneys, dilated and dysgenetic bile ducts, dilated pancreatic ducts, and polysplenia, correspond to those reported by Ivemark as renal-hepatic-pancreatic dysplasia. Many polymalformation syndromes include cystic affectation of these three organs, so this syndrome could be an isolated entity or a final common pathway of response of these organs to a variety of developmental disturbances, which could also include splenic abnormalities. We propose an autosomal recessive pattern of inheritance for renal-hepatic-pancreatic dysplasia.

Abnormalities, Multiple↗

PubMed1996

Huntington's disease: confirmation of diagnosis and presymptomatic testing in Spanish families by genetic analysis.

Huntington's disease is a neuropsychiatric disorder with late age of onset, caused by an elongation of a (CAG)n repeat in the IT15 gene. This trinucleotide repeat has been studied by polymerase chain reaction amplification in 86 members of 43 Spanish families with Huntington's disease and in 60 unrelated subjects from the general population. The number of (CAG)n repeats in Huntington's disease chromosomes varied from 40 to 85, with 49 and 52 repeats being the most common, whereas in normal chromosomes it ranged from 12 to 32 with 20 (CAG)n repeats being the most frequent allele. In four patients with juvenile onset the number of (CAG)n repeats was greater than 50 and only one was of maternal transmission. There was a clear inverse correlation between the number of repeats and the age of onset of the disease. The study contributed to the diagnosis of 10 patients in whom the clinical diagnosis was uncertain, and identified 41 "at risk" patients after a previous psychological-psychiatric evaluation.

Adolescent↗

PubMed1996

Estimation of the mutation frequencies in Charcot-Marie-Tooth disease type 1 and hereditary neuropathy with liability to pressure palsies: a European collaborative study.

A European collaboration on Charcot-Marie-Tooth type 1 (CMT1) disease and hereditary neuropathy with liability to pressure palsies (HNPP) was established to estimate the duplication and deletion frequency, respectively, on chromosome 17p11.2 and to make an inventory of mutations in the myelin genes, peripheral myelin protein 22 (PMP22), myelin protein zero (MPZ) and connexin 32 (Cx32) located on chromosomes 17p11.2, 1q21-q23 and Xq13.1, respectively. In 70.7% of 819 unrelated CMT1 patients, the 17p11.2 duplication was present. In 84.0% of 156 unrelated HNPP patients, the 17p11.2 deletion was present. In the nonduplicated CMT1 patients, several different mutations were identified in the myelin genes PMP22, MPZ and Cx32.

Charcot-Marie-Tooth Disease↗

PubMed1996

Integration of 30 CA-repeat markers into the cytogenetic, genetic and YAC maps of human chromosome 21.

The number of polymorphic DNA markers developed for the whole human genome during the last 2 years has been vastly increased. For this reason, the genetic map is continuously improving, but the cytogenetic and physical maps are not progressing at the same speed. Therefore, there is a need to integrate genetic, cytogenetic and physical mapping data. We have developed and localized on the breakpoint map of human chromosome 21 thirty microsatellite markers. Twenty of them have been used in the construction of a genetic map of chromosome 21, which contains a total of 44 markers. This map has 39 uniquely placed loci at 23 anchor points, ordered with odds of at least 1,000:1. The sex average length of the map is 64.4 cM, with the male and female lengths being 49.4 and 79.2 cM, respectively. Twenty-six of these newly developed markers have been localised on the CEPH/Généthon and Joint YAC Screening Effort YACs. Although these microsatellites were found uniformly spread along chromosome 21, the detection of various markers in the same or adjacent YACs suggests that CA-repeat microsatellites are clustered in several regions. The localization of these markers on the cytogenetic, genetic and YAC maps has provided a refined location for them and is a step further towards the construction of an integrated map of HC21.

Chromosome Mapping↗

PubMed1996

Linkage, clinical features, and prognosis of autosomal dominant polycystic kidney disease types 1 and 2.

Linkage analysis was performed on 49 Catalan families with autosomal dominant polycystic kidney disease obtained via the Nephrology Department and related nephrology centers. A total of 336 subjects, 267 at risk for the disease, were investigated using three microsatellites linked to polycystic kidney disease Type 1 (PKD1) and three microsatellites linked to PKD2. All of the subjects underwent physical and sonographic examination. The results demonstrate locus heterogeneity, with 0.85 as the maximum likelihood for the proportion of families linked to PKD1. All of the remaining families were found to be linked to PKD2. Analysis of clinical data in the PKD1 group (N = 146) versus the PKD2 group (N = 20) showed a milder form of the disease in the latter, with a later age at diagnosis (27.4 versus 41.4 yr, P = 0.0002), later age of onset of ESRD (53.4 versus 72.7 yr, P < 0.0001), later age of diagnosis of hypertension (34.8 versus 49.7 yr, P = 0.001) and lower prevalence of hypertension at younger ages. Sonographic findings did not differ significantly between both groups. Although anticipation was observed in both groups, it did not affect the majority of families. No signs of imprinting were found in this study, and the only gender effect was an earlier age of onset of ESRD in men than in women (49.5 versus 53.1 yr in PKD1, P < 0.01 and 70.57 versus 73.6 yr in PKD2, P = 0.1). Molecular analysis of autosomal-dominant polycystic kidney disease allows presymptomatic diagnosis in individuals younger than age 30, and helps in establishing prognosis.

Adult↗

PubMed1996

Abdominal aortic aneurysms and autosomal dominant polycystic kidney disease.

Although cases of autosomal dominant polycystic kidney disease (ADPKD) associated with abdominal aortic aneurysm have been repeatedly reported in the literature, no systematic studies of the aortas of these patients have been performed. In the study presented here, a sonographic study of the abdominal aorta in 139 ADPKD patients and in 149 healthy family members was carried out. For both groups, an increase in aortic diameter related to age and sex, (being wider in men than women) was found. In ADPKD patients, neither a wider aortic diameter nor a higher prevalence of abdominal aortic aneurysms could be found in any age group. It was concluded that, although these patients are prone to develop aortic aneurysms because of hypertension and associated connective tissue disorders, the presence of abdominal aortic aneurysms should be questioned as a frequent feature of ADPKD.

Adolescent↗

PubMed1996

Autosomal recessive Wolfram syndrome associated with an 8.5-kb mtDNA single deletion.

Wolfram syndrome (MIM 222300) is characterized by optic atrophy, diabetes mellitus, diabetes insipidus, neurosensory hearing loss, urinary tract abnormalities, and neurological dysfunction. The association of clinical manifestations in tissues and organs unrelated functionally or embryologically suggested the possibility of a mitochondrial implication in the disease, which has been demonstrated in two sporadic cases. Nonetheless, familial studies suggested an autosomal recessive mode of transmission, and recent data demonstrated linkage with markers on the short arm of human chromosome 4. The patient reported here, as well as her parents and unaffected sister, carried a heteroplasmic 8.5-kb deletion in mtDNA. The deletion accounted for 23% of mitochondrial genomes in lymphocytes from the patient and approximately 5% in the tissues studied from members of her family. The presence of the deletion in the patient in a proportion higher than in her unaffected parents suggests a putative defect in a nuclear gene that acts at the mitochondrial level.

Base Sequence↗

PubMed1996

Ectopic transcript analysis indicates that allelic exclusion is an important cause of type I protein C deficiency in patients with nonsense and frameshift mutations in the PROC gene.

Nonsense mutations, deletions and splice site mutations are a common cause of type I protein C deficiency. Either directly or indirectly by altering the reading frame, these lesions generate or may generate premature stop codons and could therefore be expected to result in premature termination of translation. In this study, the possibility that such mutations could instead exert their pathological effects at an earlier stage in the expression pathway, through "allelic exclusion" at the RNA level, was investigated. Protein C (PROC) mRNA was analysed in seven Spanish type I protein C deficient patients heterozygous for two nonsense mutations, a 7bp deletion, a 2bp insertion and three splice site mutations. Ectopic RNA transcripts from patient and control lymphocytes were analysed by RT-PCR and direct sequencing of amplified PROC cDNA fragments. The nonsense mutations and the deletion were absent from the cDNAs indicating that only mRNA derived from the normal allele had been expressed. Similarly for the splice site mutations, only normal PROC cDNAs were obtained. In one case, exclusion of the mutated allele could be confirmed by polymorphism analysis. In contrast to these six mutations, the 2 bp insertion was not associated with loss of mRNA from the mutated allele. In this case, cDNA analysis revealed the absence of 19 bases from the PROC mRNA consistent with the generation and utilization of a cryptic splice site 3' to the site of mutation, which would result in a frameshift and a premature stop codon. It is concluded that allelic exclusion is a common causative mechanism in those cases of type I protein C deficiency which result from mutations that introduce premature stop codons.

Alleles↗

PubMed1995

Genetic heterogeneity in cystinuria: the SLC3A1 gene is linked to type I but not to type III cystinuria.

Cystinuria is an autosomal recessive amino-aciduria where three urinary phenotypes have been described (I, II, and III). An amino acid transporter gene, SLC3A1 (formerly rBAT), was found to be responsible for this disorder. To assess whether mutations in SLC3A1 are involved in different cystinuria phenotypes, linkage with this gene and its nearest marker (D2S119) was analyzed in 22 families with type I and/or type III cystinuria. Linkage with heterogeneity was proved (alpha = 0.45; P < 0.008). Type I/I families showed homogeneous linkage to SLC3A1 (Zmax > 3.0 at theta = 0.00; alpha = 1), whereas types I/III and III/III were not linked. Our data suggest that type I cystinuria is due to mutations in the SLC3A1 gene, whereas another locus is responsible for type III. This result establishes genetic heterogeneity for cystinuria, classically considered as a multiallelic monogenic disease.

Adolescent↗

PubMed1995

[Progressive external ophthalmoplegia and the Kearns-Sayre syndrome: a clinical and molecular study of 6 cases].

The Kearns-Sayre syndrome (KSS) associates progressive external ophthalmoplegia initiating prior to the age of 20 years and pigmentary retinitis with a series of other heterogeneous clinical manifestations. The incomplete syndrome is usually denominated progressive external ophthalmoplegia (PEO)-plus which is a sporadically appearing mitochondrial cytopathy associated with large deletions of a variable proportion of mitochondrial DNA (mtDNA) molecules. Six patients with PEO-plus/KSS in whom muscle biopsy was performed following a complete clinical study are described. The muscle was processed by conventional histochemical techniques, electron microscopy, and genetic study (Southern transference, polymerase chain reaction, restriction cartography and both manual and automatic sequencing). The percentage of mutated mtDNA molecules for each patient was obtained by densitometry. The 6 patients presented multiorganic clinical manifestations characteristics of most mitochondrial diseases. The presence of destructured red fibers were observed in all the biopsies. All the patients presented a deletion in the mtDNA of a size between 4,861 to 7,437 base pairs (bp). All the deletions appeared flanked by direct repetitions from 4 to 13 bp and one also presented inverse repetitions from 5 to 6 bp in the zone next to the rupture point. In the 6 cases heteroplasmia was observed with a variable percentage of deleted molecules from 23 to 56%. The molecular basis of progressive external ophthalmoplegia-plus/Kearns-Sayre syndrome appears to be the existence of sole, large deletions in the mitochondrial DNA with the varying in location and percentage conditioning the appearance of different phenotypes similar among themselves. The 7,437 base pair deletion was the most frequently observed in the patients analyzed.

Adolescent↗

PubMed1995

The human collagenase-3 (CLG3) gene is located on chromosome 11q22.3 clustered to other members of the matrix metalloproteinase gene family.

The gene coding for human collagenase-3 (CLG3), a recently described matrix metalloproteinase produced by breast carcinomas, has been localized by fluorescence in situ hybridization on chromosome 11q22.3. Physical mapping of an isolated YAC clone containing CLG3 has revealed that this gene is tightly linked to those encoding other matrix metalloproteinases, including fibroblast collagenase (CLG1), stromelysin-1 (STMY1), and stromelysin-2 (STMY2). Further mapping of this region using pulsed-field gel electrophoresis has shown that the CLG3 gene is localized to the telomeric side of the matrix metalloproteinase cluster, the relative order of the loci being centromere-STMY2-CLG1-STMY1-CLG3-telomere.

Base Sequence↗

PubMed1995

Simultaneous on-line DNA sequencing on both strands with two fluorescent dyes.

We describe an automated DNA-sequencing technique which allows both the simultaneous sequencing from the two strands of double-stranded templates and the subsequent detection of the sequencing products online and in parallel. The technique is based on hardware technology also used in the ALF DNA sequencer (Pharmacia, Uppsala). A helium-neon laser was mounted into the sequencing device additionally to the standard argon laser. Two different primers, labeled with either fluorescein or Texas red, are used in a single sequencing reaction resulting in an output of two sequences. Both sequencing products are then analyzed on-line in the same lanes of a gel. This technique is especially useful for the complete sequencing of DNA fragments up to 1 kb. High accuracy sequencing of PCR products in double-stranded form can now be accomplished in only one sequencing reaction.

Fluorescent Dyes↗