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Biomedical subjects

X Estivill

Publications and source records attributed to X Estivill.

At least 253 records · Page 14Linked to original sources
PubMed1994

A cystic fibrosis patient homozygous for the new frameshift mutation 936delTA: description and clinical data.

We report the identification of a new frameshift mutation (936delTA) in exon 6b of the CFTR gene. In the screening of 486 unrelated Spanish CF patients we found a patient homozygous for 936delTA (with consanguineous parents) and a patient heterozygous for delta F508 and 936delTA. Genotype-phenotype correlation studies showed that 936delTA is associated with pancreatic insufficiency and chronic pulmonary colonisation.

Base Sequence↗
PubMed1994

Chemiluminescent detection of blotted PCR products (CB-PCR) of two CAG dynamic mutations (Huntington's disease and spinocerebellar ataxia type 1).

We have used a non-isotopic PCR assay based on the chemiluminescent detection of blotted PCR products (CB-PCR) for two dynamic mutation diseases (Huntington's disease and spinocerebellar ataxia type 1). This gives an accurate sizing of alleles and permits a rapid analysis of at risk persons. The system involves PCR of the samples, separation of alleles on polyacrylamide gels, Southern blotting, and hybridisation with specific primers 3' labelled with fluorescein (F1)-dUTP as probes. CB-PCR retains the isotopic sensitivity for accurate allele determination, avoids isotopic manipulation, and provides the advantages of safety, long term storage of probes, and recycling of hybridisation solutions.

Alleles↗
PubMed1994

A cluster of cystic fibrosis mutations in exon 17b of the CFTR gene: a site for rare mutations.

Intensive screening has improved our understanding of the profile of mutations in the CFTR gene in which more than 400 mutations have been detected to date. In collaboration with several European laboratories we are involved in such analysis. We have identified 14 new mutations in exon 17b of CFTR, having analysed 780 CF chromosomes, and have compared the frequency of mutations in this exon with that of other regions of the CFTR gene. The results obtained indicate an accumulation of mutations, not only in regions encoding the two nucleotide binding folds, but also in those encoding transmembrane domains of the CFTR gene, in particular exon 17b.

Cystic Fibrosis↗
PubMed1994

Mapping of the human Zn-alpha 2-glycoprotein gene (AZGP1) to chromosome 7q22 by in situ hybridization.

The gene coding for Zn-alpha 2-glycoprotein (AZGP1), a human protein with a high degree of similarity to class I major histocompatibility complex (MHC) antigens, was mapped by fluorescent in situ hybridization to chromosome 7q22, a common breakpoint in myelodysplastic syndromes. Since classical MHC genes map on chromosome 6, this assignment indicates that besides duplication of the putative common ancestor gene, transposition events to different chromosomes have also been involved in the evolutionary diversification of this gene family.

Cells, Cultured↗
PubMed1994

Independent origins of cystic fibrosis mutations R334W, R347P, R1162X, and 3849 + 10kbC-->T provide evidence of mutation recurrence in the CFTR gene.

Microsatellite analysis of chromosomes carrying particular cystic fibrosis mutations has shown different haplotypes in four cases: R334W, R347P, R1162X, and 3849 + 10kbC-->T. To investigate the possibility of recurrence of these mutations, analysis of intra- and extragenic markers flanking these mutations has been performed. Recurrence is the most plausible explanation, as it becomes necessary to postulate either double recombinations or single recombinations in conjunction with slippage at one or more microsatellite loci, to explain the combination of mutations and microsatellites if the mutations arose only once. Also in support of recurrence, mutations R334W, R347P, R1162X, and 3849 + 10kbC-->T involve CpG dinucleotides, which are known to have an increased mutation rate. Although only 15.7% of point mutations in the coding sequence of CFTR have occurred at CpG dinucleotides, approximately half of these CpG sites have mutated at least once. Specific nucleotide positions of the coding region of CFTR, distinct from CpG sequences, also seem to have a higher mutation rate, and so it is possible that the mutations observed are recurrent. G-->A transitions are the most common change found in those positions involved in more than one mutational event in CFTR.

Base Sequence↗
PubMed1994

Severe homozygous protein C deficiency: identification of a splice site missense mutation (184, Q-->H) in exon 7 of the protein C gene.

Single strand conformation polymorphism (SSCP) analysis of exon 7 of the protein C gene has identified a novel splice site missense mutation (184, Q-->H), in a newborn child with purpura fulminans and undetectable protein C levels. The mutations, seen in the homozygous state in the child and in the heterozygous state in her mother, was characterized and found to be a G to C nucleotide substitution at the -1 position of the donor splice site of intron 7 of the protein C gene, which changes histidine 184 for glutamine (184, Q-->H). According to analysis of the normal and mutated sequences, this mutation should also abolish the function of the donor splice site of intron 7 of the protein C gene. Since such a mutation is compatible with the absence of gene product in plasma and since DNA sequencing of all protein C gene exons in this patient did not reveal any other mutation, we postulate that mutation 184, Q-->H results in the absence of protein C gene product in plasma, which could be the cause of the severe phenotype observed in this patient.

Base Sequence↗
PubMed1994

Fragile X syndrome and the (CGG)n mutation: two families with discordant MZ twins.

The fragile X phenotype has been found, in the majority of cases, to be due to the expansion of a CGG repeat in the 5'-UTR region of the FMR-1 gene, accompanied by methylation of the adjacent CpG island and inactivation of the FMR-1 gene. Although several important aspects of the genetics of fragile X have been resolved, it remains to be elucidated at which stage in development the transition from the premutation to the full mutation occurs. We present two families in which discordance between two sets of MZ twins illustrates two important genetic points. In one family, two affected MZ brothers differed in the number of CGG repeats, demonstrating in vivo mitotic instability of this CGG repeat and suggesting that the transition to the full mutation occurred postzygotically. In the second family, two MZ sisters had the same number of repeats, but only one was mentally retarded. When the methylation status of the FMR-1 CpG island was studied, we found that the majority of normal chromosomes had been inactivated in the affected twin, thus leading to the expression of the fragile X phenotype.

Adolescent↗
PubMed1993

Expression cloning of a human renal cDNA that induces high affinity transport of L-cystine shared with dibasic amino acids in Xenopus oocytes.

A renal cDNA clone (rBAT) that induces system bo,+-like amino acid transport activity in Xenopus oocytes has recently been isolated (Bertran, J., Werner, A., Moore, M. L., Strange, G., Markovich, D., Biber, J., Testar, X., Zorzano, A., Palacín, and Murer, H. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 5601-5605). Here we show the isolation of a cDNA clone by screening a human kidney cortex cDNA library for expression of sodium-independent transport of L-[3H]arginine in Xenopus oocytes. The cRNA of this clone induces in oocytes, in addition to the uptake of L-arginine, that of L-[35S]cystine and L-[3H]leucine. Expressed uptake of these amino acids is mutually cis-inhibitable by the other 2 amino acids. Expressed uptake of L-cystine is saturable and shows an apparent Km in the micromolar range. All these characteristics resemble induction of system bo,+ related to rBAT in the oocytes. Human rBAT mRNA (approximately 2.5 kilobases) is found in kidney, small intestine (i.e., jejunum), pancreas, and liver. Human kidney poly(A)+ RNA (mRNA) induces sodium-independent uptake of L-cystine, L-arginine, and L-leucine in Xenopus oocytes. Hybrid depletion with an antisense oligonucleotide of the isolated clone greatly prevents (80-97%) human kidney mRNA-dependent induction of the uptake of these amino acids (i.e., L-cystine, L-arginine, and L-leucine). The isolated clone (2304 base pairs in length) contains a poly(A) tail and encodes a predicted 78.8-kDa protein which is 85 and 80% identical to the rabbit and rat rBAT, respectively. This predicted protein corresponds to a membrane glycoprotein, and contains six potential N-glycosylation sites which might be functional in the oocyte: [35S] methionine labeling of oocytes shows a specific band of 94 kDa in crude membranes of these human cRNA-injected oocytes; treatment of these oocytes with tunicamycin shifts the cRNA-specific translation product to approximately 72 kDa. We conclude that we have isolated a functional cDNA corresponding to human rBAT. The isolation of this human cDNA would lead to the study of the possible involvement of rBAT in human hyperaminoacidurias.

Amino Acid Sequence↗
PubMed1993

Isolation and characterization of 14 CA-repeat microsatellites from human chromosome 21.

Fourteen CA-repeat microsatellite polymorphisms from human chromosome 21 (HC21) (D21S364, D21S365, D21S366, D21S367, D21S368, D21S369, D21S406, D21S407, D21S408, D21S409, D21S410, D21S411, D21S415, and D21S1217) have been cloned from a flow-sorted phage library (LA21NS01). These microsatellite loci have been mapped using a somatic cell hybrid panel of HC21, and heterozygosities and allele frequencies have been determined. The markers spread along the length of the long arm of the HC21. Twelve of these microsatellites have heterozygosities between 0.47 and 0.90. These new CA-repeat markers will improve the genetic map of HC21.

Animals↗
PubMed1993

Acceptor splice site mutation in the invariant AG of intron 5 of the protein C gene, causing type I protein C deficiency.

An acceptor splice-site mutation (3318, A-->G) in the invariant AG of intron 5 of the human protein C gene has been identified in a Spanish family with heterozygous type I protein C (PC) deficiency and thromboembolic disease. Family studies confirmed cosegregation of the mutation with type I PC deficiency. Computer analysis of the mutated sequence predicted the normal splicing site to be abolished by this mutation, whereas a cryptic splice site located two nucleotides downstream, in exon 6, is probably activated. According to this, 3318, A-->G should result in a frameshift with a stop at codon 119, in agreement with the presence of a type I or quantitative PC deficient phenotype in the affected members of the family.

Adult↗
PubMed1993

Cystic fibrosis in Spain: high frequency of mutation G542X in the Mediterranean coastal area.

We have determined the frequency of deletion delta F508 and mutation G542X, a nonsense mutation in exon 11 of the cystic fibrosis (CF) gene, in a sample of 400 Spanish CF families. Mutation G542X represents 8% of the total number of CF mutations in Spain, making it the second most common mutation after the delta F508 deletion, which accounts for 48% of CF chromosomes. G542X has a higher frequency in the Mediterranean coastal area (14%) and in the Canary Islands (25%). About 70% of G542X chromosomes are from Andalucia, Múrcia, Valencia, Catalunya and the Canary Islands. The delta F508 deletion has its highest frequency in the Basque Country (83%). Mutation G542X is associated with the same rare haplotype that is found in association with the delta F508 mutation. The haplotype homogeneity found for G542X, even when intragenic microsatellites (IVS8CA, IVS17BTA and IVS17BCA) are considered, allows us to postulate that this mutation arose from a single mutational event. The geographic distribution of mutations delta F508 and G542X suggests that delta F508 was present in the Iberian Peninsula before the Indo-European invasions, and that G542X was introduced into Spain, via the Mediterranean Sea, probably by the Phoenicians, between 2500 and 3000 years ago.

Base Sequence↗
PubMed1993

Genetic variation of microsatellite markers D1S117, D6S89, D11S35, APOC2, and D21S168 in the Spanish population.

We have used PCR amplification to analyse the allele frequency, distribution and heterozygosity of 5 microsatellite markers (D1S117, D6S89, D11S35, APOC2, and D21S168), in a sample of 100 unrelated Spanish individuals. The loci tested exhibit wide allelic variability having 7-17 alleles, PIC (polymorphic information content) between 0.79 and 0.86, and heterozygosity between 0.81 and 0.86. D1S117 and D21S168 have unimodal distribution, APOC2 has 4 common alleles which account for 71% of the total variation, D11S35 has a bimodal distribution and D6S89 is trimodal. The allelic distribution observed for each locus is in agreement with slippage and mispairing as the main mechanisms involved in the evolution of microsatellite alleles. Multiplex amplification of loci D6S89 and APOC2 was possible due to their non-overlapping allele sizes. The rapidity with which microsatellites can be analysed, and the accurate determination of alleles, make these markers very powerful tools for genetic typing. The information obtained for loci D1S117, D6S89, D11S35, APOC2, and D21S168, provides a basis for their use for DNA typing and paternity analysis in the Spanish population.

Alleles↗