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X Estivill

Publications and source records attributed to X Estivill.

At least 127 records · Page 7Linked to original sources
PubMed1999

The A1555G mutation in the 12S rRNA gene of human mtDNA: recurrent origins and founder events in families affected by sensorineural deafness.

The mtDNA variation of 50 Spanish and 4 Cuban families affected by nonsyndromic sensorineural deafness due to the A1555G mutation in the 12S rRNA gene was studied by high-resolution RFLP analysis and sequencing of the control region. Phylogenetic analyses of haplotypes and detailed survey of population controls revealed that the A1555G mutation can be attributed to >/=30 independent mutational events among the 50 Spanish families and that it occurs on mtDNA haplogroups that are common in all European populations. This indicates that the relatively high detection rate of this mutation in Spain is not due to sampling biases or to a single major founder event. Moreover, the distribution of these mutational events on different haplogroups is compatible with a random occurrence of the A1555G mutation and tends to support the conclusion that mtDNA backgrounds do not play a significant role in the expression of the mutation. Overall, these findings appear to indicate that the rare detection of this mutation in other populations is most likely due to inadequacy in patient ascertainment and molecular screening. This probable lack of identification of the A1555G mutation in subjects affected by sensorineural hearing loss implies that their maternally related relatives are not benefiting from presymptomatic detection and information concerning their increased risk of ototoxicity due to aminoglycoside treatments.

DNA Mutational Analysis↗
PubMed1999

Vestibular and hearing loss in genetic and metabolic disorders.

Hearing loss affects about 4% of people under 45 years of age and comprises a broad spectrum of clinical presentations (congenital or late-onset, conductive or sensorineural, and syndromic or nonsyndromic). Approximately 30% of genetically determined deafness is reported to occur in syndromic form and 70% in nonsyndromic form. This review highlights recent advances in the molecular and genetic basis of hearing loss, which will help in understanding the biology of normal and abnormal hearing.

Chromosome Aberrations↗
PubMed1999

A high-resolution physical map of human chromosome 21p using yeast artificial chromosomes.

The short arm of human chromosome 21 (21p) contains many different types of repetitive sequences and is highly homologous to the short arms of other acrocentric chromosomes. Owing to its repetitive nature and the lack of chromosome 21p-specific molecular markers, most physical maps of chromosome 21 exclude this region. We constructed a physical map of chromosome 21p using sequence tagged site (STS) content mapping of yeast artificial chromosomes (YACs). To this end, 39 STSs located on the short arm or near the centromere of chromosome 21 were constructed, including four polymorphic simple tandem repeats (STRs) and two expressed sequence tags (ESTs). Thirty YACs were selected from the St. Louis YAC library, the chromosome 21-enriched ICRF YAC library, and the CEPH YAC and megaYAC libraries. These were assembled in a YAC contig map ranging from the centromere to the rDNA gene cluster at 21p12. The total size of the region covered by YACs is estimated between 2.9 and 5 Mb. The integrity of the YAC contig was confirmed by restriction enzyme fingerprinting and fluorescence in situ hybridization (FISH). One gap with an estimated size of 400 kb remained near the telomeric end of the contig. This YAC contig map of the short arm of human chromosome 21 constitutes a basic framework for further structural and functional studies of chromosome 21p.

Chromosomes, Artificial, Yeast↗
PubMed1999

Cloning, expression, and mapping of PDCD9, the human homolog of Gallus gallus pro-apoptotic protein p52.

We report the sequence, tissue distribution, and chromosome location of a novel gene, PDCD9 (programmed cell death 9). PDCD9 is the mammalian counterpart of the Gallus gallus pro-apoptotic protein p52. The human cDNA has an open reading frame of 1,314 nucleotides and was predicted to encode a protein of 438 amino acids with a calculated mass of 50 kDa. The protein sequences of chicken, mouse, and human PDCD9 are remarkably conserved. PDCD9 mRNA is expressed ubiquitously in adult tissues, displaying a stronger signal in heart, skeletal muscle, kidney, and liver. PDCD9 was mapped to chromosome 5q11.

Amino Acid Sequence↗
PubMed1999

Allele specific oligonucleotide analysis of the common deafness mutation 35delG in the connexin 26 (GJB2) gene.

Despite the large number of genes that are expected to be involved in non-syndromal, recessive deafness, only a few have been cloned. One of these genes is GJB2, which encodes connexin 26. A frameshift mutation in this gene has been reported to be common in several populations and a carrier frequency of about 1 in 30 people has been detected in Italy and Spain. Mutation 35delG is difficult to detect because it lies within a stretch of six guanines flanked by thymines, so the deletion of one G does not create or destroy a restriction site and mutagenesis primers are not useful for this mutation. We have generated an allele specific oligonucleotide method that uses 12-mer oligonucleotides and easily discriminates between the normal and 35delG alleles. The method should permit a rapid analysis of this mutation in congenital cases (recessive or sporadic), including diagnosis and carrier detection of 35delG in the population.

Alleles↗
PubMed1999

Prenatal diagnosis of sporadic neurofibromatosis type 1 (NF1) by RNA and DNA analysis of a splicing mutation.

Neurofibromatosis type 1 (NF1) is one of the most common genetic disorders in humans with an incidence of 1 in 3500. Most of the NF1 mutations reported so far (over 240 mutations) are unique. Specific prenatal diagnosis can only be provided to familial cases by an indirect linkage analysis or to families with a previously identified mutation. Here we report the first prenatal diagnosis in sporadic NF1 by direct characterization of the mutation. We first identified the skipping of exon 10b of NF1 in the mRNA from a woman affected by NF1 and without familial history of the disease. The analysis of genomic DNA identified mutation IVS10b+1G-->A as the cause of the skipping of exon 10b. Chorionic villus sampling (CVS) was performed at 10 weeks of gestation and total RNA was directly extracted from the sample. After reverse transcription (RT) and polymerase chain reaction (PCR) of the cDNA, the skipping of exon 10b was not identified in the CVS upon agarose gel electrophoresis. The fetal origin of the CVS was confirmed via polymorphic markers and the absence of the IVS10b+1G-->A mutation was confirmed by genomic analysis.

Adult↗
PubMed1999

CDKN2A mutations in Spanish cutaneous malignant melanoma families and patients with multiple melanomas and other neoplasia.

The CDKN2A gene has been implicated in cutaneous malignant melanoma (CMM) in about 40% of families with linkage to chromosome 9p21, while a small proportion of families have mutations in the CDK4 gene. In order to estimate the importance of these genes in the predisposition to CMM in Spanish families and patients we have analysed, by SSCA, a total of 56 subjects belonging to 34 CMM families, and nine patients with multiple CMM and other neoplasia. We have detected germline CDKN2A mutations in six out of the 34 families (17%). A frameshift mutation (358delG) and four missense mutations (G59V, G101W (two cases), D84Y, and R87W) were identified. Five CMM patients from different families (14%) carried the A148T variant, which is known not to affect p16 activity. No mutations were detected in the patients with multiple CMM or other neoplasms. We have not found mutations either in exon 1 beta of the CDKN2A gene or in exon 2A of CDK4. Linkage analysis of the 9p21 region showed exclusion for one of the families for CMM and for four families for CMM/dysplastic naevi. This study indicates a small role for CDKN2A in Spanish CMM families and suggests that other genes are also responsible for CMM predisposition.

Carrier Proteins↗
PubMed1998

Cloning, chromosome mapping and expression analysis of the HIRA gene from Drosophila melanogaster.

The human HIRA gene was identified as a putative transcriptional regulator mapping within the DiGeorge syndrome critical region at 22q11. HIRA-related proteins have been described in a number of species, but functional information concerning family members is only available in Saccharomyces cerevisiae, where the Hir1p and Hir2p proteins are known to be transcriptional corepressors. In order to analyse conservation of HIRA-related genes and to provide resources for functional studies in another model organism we have isolated the HIRA gene from Drosophila melanogaster (dhira). The 3374 nucleotide cDNA encodes a protein of 1047 aa, showing 42% identity with the human protein. Alignment with the predicted HIRA proteins from human, mouse, chick and pufferfish reveals strong conservation within the N-terminal region which contains seven WD domains, with less conservation of C-terminal sequences. In situ hybridisation to salivary gland chromosomes indicates that the gene resides in region 7B2-3 of the X chromosome. Dhira is expressed through embryonic development and at lower levels during larval and pupal development. The expression of dhira is dramatically increased in early embryos and in females, suggesting that the dhira mRNA could be maternally deposited in the embryos.

Amino Acid Sequence↗
PubMed1998

Retention of the CDKN2A locus and low frequency of point mutations in primary and metastatic cutaneous malignant melanoma.

CDKN2A has been found mutated in melanoma families which show linkage to chromosome 9p21. In contrast, a low mutation rate has been found in melanomas, suggesting that CDKN2A might not be the first target for mutation in the development of this type of tumour. To elucidate the role of the CDKN2A gene and its alternative transcript p19ARF in the development of cutaneous malignant melanoma (CMM) we have analyzed 48 primary and metastasic CMM tumours for mutations and for loss of heterozygosity (LOH). Only one point mutation was detected (2%), while hemizygous deletions were identified in 20% of these tumours. Retention of the CDKN2A locus was found in 10 (47%) tumours with deletions at one or both sides of CDKN2A, suggesting that loss of this gene is not involved in CMM-tumour initiation and that another tumour-suppressor gene involved in melanoma is located at 9p21.

Gene Deletion↗
PubMed1998

[Clinical, genetic and molecular studies on autosomal dominant polycystic kidney disease].

BACKGROUND: Two genes causing autosomal dominant polycystic kidney disease (ADPKD), PKD1 and PKD2, have been described. In the present work we study, by means of linkage analysis, the genetic heterogeneity in our population as well as the clinical differences between PKD1 and PKD2. SUBJECTS AND METHODS: 316 subjects belonging to 49 unrelated ADPKD families have been studied by means of 3 microsatellites for PKD1 and 3 for PKD2 to differentiate if they have ADPKD type 1 or 2. The techniques used to analyze the microsatellites have been the chemiluminescence and the silver satining techniques. All the subjects underwent a complete physical examination and a sonographic scan. Clinical and molecular results have been correlated. RESULTS: Genetic heterogeneity has been proved, with 85% of families linked to PKD1 and 15% to PKD2. The disease is more severe in PKD1, with an earlier age at diagnosis (27.4 vs. 41.4 years; p = 0.0002), a younger age at the onset of end stage renal disease (53.4 vs. 72.7 years, p < 0.00001), and earlier age at diagnosis of hypertension (34.8 vs. 49.7 years; p = 0.001) and a higher prevalence of hypertension for all groups of age. In both forms of ADPKD there were families showing anticipation (8/44 for PKD1 and 2/5 for PKD2) but this was not a widespread phenomenon. Our data do not support the phenomenon of genetic imprinting for this disease. CONCLUSION: In the population of Catalonia, Spain, PKD1 accounts for 85% of families with autosomal dominant polycystic kidney disease and PKD2 accounts for the remaining 15%. PKD1 form is more severe than PKD2.

Adult↗
PubMed1998

Large CAG/CTG repeat templates produced by PCR, usefulness for the DIRECT method of cloning genes with CAG/CTG repeat expansions.

We report here a simple method for generating large CAG/CTG repeat sequences. We have applied this method to clone the genomic sequence containing the CAG/CTG repeat and its upstream intronic sequence present in spinocerebellar ataxia type 3 or Machado-Joseph disease (SCA3/MJD) by a modified DIRECT method. With these modifications we have considerably simplified the generation of the repeat probe used to screen for anomalous bands. This method will facilitate the molecular approach to other genetic disorders where expansions of repeat sequences could be involved.

Base Sequence↗
PubMed1998

Isolation and genomic characterization of the TUPLE1/HIRA gene of the pufferfish Fugu rubripes.

In an effort to obtain a small genomic construct for the generation of a HIRA transgenic mouse, we have isolated and sequenced the Fugu TUPLE1/HIRA gene. We have compared the gene organization and the proteins encoded in pufferfish and human and also searched for conserved DNA sequences that might be important in gene regulation. The pufferfish gene spans approx. 9 kb, which is approx. 11 times smaller than the human gene, owing to the reduced size of the introns. Like its human counterpart, it is organized into 25 exons. The majority of the splice sites are in identical positions to those found in the human gene, however, for three internal exons the positions of the splice sites are not directly comparable. The coding regions are almost identical in size and show a high degree of similarity, especially at the amino and carboxy termini. Comparisons of 5' and 3' sequences failed to detect similarities or sequences involved in regulation.

Amino Acid Sequence↗
PubMed1998

Connexin-26 mutations in sporadic and inherited sensorineural deafness.

BACKGROUND: Hearing impairment affects one infant in 1000 and 4% of people aged younger than 45 years. Congenital deafness is inherited or apparently sporadic. We have shown previously that DFNB1 on chromosome 13 is a major locus for recessive deafness in about 80% of Mediterranean families and that the connexin-26 gene gap junction protein beta2 (GJB2) is mutated in DFNB1 families. We investigated mutations in the GJB2 gene in familial and sporadic cases of deafness. METHODS: We obtained DNA samples from 82 families from Italy and Spain with recessive non-syndromic deafness and from 54 unrelated participants with apparently sporadic congenital deafness. We analysed the coding region of the GJB2 gene for mutations. We also tested 280 unrelated people from the general populations of Italy and Spain for the frameshift mutation 35delG. FINDINGS: 49% of participants with recessive deafness and 37% of sporadic cases had mutations in the GJB2 gene. The 35delG mutation accounted for 85% of GJB2 mutations, six other mutations accounted for 6% of alleles, and no changes in the coding region of GJB2 were detected in 9% of DFNB1 alleles. The carrier frequency of mutation 35delG among people from the general population was one in 31 (95% CI one in 19 to one in 87). INTERPRETATION: Mutations in the GJB2 gene are a major cause of inherited and apparently sporadic congenital deafness. Mutation 35delG is the most common mutation for sensorineural deafness. Identification of 35delG and other mutations in the GJB2 gene should facilitate diagnosis and counselling for the most common genetic form of deafness.

Chromosomes, Human, Pair 13↗
PubMed1998

Two novel mutations in exon 11 of the PAH gene (V1163del TG and P362T) associated with classic phenylketonuira and mild phenylketonuria. Mutations in brief no. 143. Online.

PKU is one of the commonest genetic disease in man, affecting 1/10,000 individuals. It presents a wide phenotypical spectrum, from classic PKU to moderate Hyperpheylalaninemia depending on the residual enzymatic activity. Two novel mutations 1163/1164delTG and P362T in exon 11 have been detected during the mutational screening of the PAH gene in 84 families. 1163/1164delTC can be confused with V388M if the mutational screening is performed with BsaAI restriction enzyme, this mutation in heterozigosis presents a moderate phenotype. P362T mutation in heterozigosis with V388M shows a classical PKU phenotype. We report here two new mutations in exon 11 of the PAH gene (GenBank U49897), V1163delTG and P362T (using cDNA sequence), detected during the analysis of 57 PKU and 36 HPA patients belonging to 84 unrelated families detected under a neonatal screening program performed in Catalonia.

DNA Mutational Analysis↗