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X Estivill

Publications and source records attributed to X Estivill.

At least 145 records · Page 8Linked to original sources
PubMed1998

Facilitated diagnosis of the contiguous gene syndrome: tuberous sclerosis and polycystic kidneys by means of haplotype studies.

Tuberous sclerosis (TSC) and autosomal dominant polycystic kidney disease (ADPKD) are genetically heterogeneous diseases. The major gene for ADPKD (PKD1) lies adjacent to the TSC2 gene on chromosome 16p13. Some reports in the literature referred to an unusual presentation of TSC with enlarged cystic kidneys at birth, but it was not until the localization of the TSC2 and PKD1 genes that it was possible to analyze the interaction between both genes. We describe a case of a child with TSC and enlarged cystic kidneys. The study of genetic marker segregation in the family pointed to the presence of a deletion involving the 3' region of PKD1. A further study of the region showed a deletion of 40 kb involving both PKD1 and TSC2. We suggest that an additive or synergistic effect between PKD1 and TSC2 may cause this renal phenotype. A contiguous gene syndrome involving PKD1 and TSC2 should be suspected in children with TSC and enlarged polycystic kidneys at birth. The first approach to identify a deletion of both genes could be the analysis of the segregation of PKD1 and TSC2 markers in the family.

Chromosomes, Human, Pair 16↗
PubMed1998

Familial progressive sensorineural deafness is mainly due to the mtDNA A1555G mutation and is enhanced by treatment of aminoglycosides.

Hearing loss involves both genetic and environmental factors. A mutation (A1555G) in the mtDNA has been associated with aminoglycoside-induced and nonsyndromic sensorineural deafness. The pathological significance of this mutation in Caucasoid families has not been established, and its relationship with antibiotic treatment is not well understood. We studied 70 Spanish families with sensorineural deafness (36 congenital and 34 late onset) for the mtDNA A1555G mutation. The A1555G mutation was found in 19 families with maternally transmitted deafness but not in the other 51 families or in 200 control subjects. In 12 families all the patients with the A1555G mutation who received aminoglycosides became deaf, representing 30.3% of the deaf patients in these families. None of the deaf patients from seven other families received aminoglycosides. Overall, only 17.7% of the patients with deafness and the A1555G mutation had been treated with aminoglycosides. The age at onset of deafness was lower (median age 5 years, range 1-52 years) in those treated with aminoglycosides than in those who did not receive antibiotics (median age 20 years, range 1-65 years) (P < .001). The mtDNA of these families belongs to haplotypes common in Europeans. These data indicate that the A1555G mutation accounts for a large proportion of the Spanish families with late-onset sensorineural deafness, that the A1555G mutation has an age-dependent penetrance for deafness (enhanced by treatment with aminoglycosides), and that mtDNA backgrounds probably do not play a major role in disease expression.

Adolescent↗
PubMed1998

A clinical variant of neurofibromatosis type 1: familial spinal neurofibromatosis with a frameshift mutation in the NF1 gene.

Spinal neurofibromatosis (SNF) has been considered to be an alternative form of neurofibromatosis in which spinal cord tumors are the main clinical characteristic. Familial SNF has been reported, elsewhere, in three families-two linked to markers within the gene for neurofibromatosis type 1 (NF1) and the other not linked to NF1-but no molecular alterations have been described in these families. We describe a three-generation family that includes five members affected by SNF. All the affected members presented multiple spinal neurofibromas and café au lait spots, one member had cutaneous neurofibromas, and some members had other signs of NF1. Genetic analysis, performed with markers within and flanking the NF1 gene, showed segregation with the NF1 locus. Mutation analysis, performed with the protein-truncation test and SSCP/heteroduplex analysis of the whole coding region of the NF1 gene, identified a frameshift mutation (8042insA) in exon 46, which should result in a truncated NF1 protein. The 8042insA mutation was detected in all five family members with the SNF/NF1 phenotype. To our knowledge, this is the first time that a mutation in the NF1 gene has been associated with SNF. The clinical homogeneity in the severity of the disease among the affected members of the family, which is unusual in NF1, suggests that a particular property of the NF1 mutation described here, a gene closely linked to NF1, or posttranscriptional events are involved in this severe neurological phenotype.

Adult↗
PubMed1998

Dating the origin of the CCR5-Delta32 AIDS-resistance allele by the coalescence of haplotypes.

The CCR5-Delta32 deletion obliterates the CCR5 chemokine and the human immunodeficiency virus (HIV)-1 coreceptor on lymphoid cells, leading to strong resistance against HIV-1 infection and AIDS. A genotype survey of 4,166 individuals revealed a cline of CCR5-Delta32 allele frequencies of 0%-14% across Eurasia, whereas the variant is absent among native African, American Indian, and East Asian ethnic groups. Haplotype analysis of 192 Caucasian chromosomes revealed strong linkage disequilibrium between CCR5 and two microsatellite loci. By use of coalescence theory to interpret modern haplotype genealogy, we estimate the origin of the CCR5-Delta32-containing ancestral haplotype to be approximately 700 years ago, with an estimated range of 275-1,875 years. The geographic cline of CCR5-Delta32 frequencies and its recent emergence are consistent with a historic strong selective event (e.g. , an epidemic of a pathogen that, like HIV-1, utilizes CCR5), driving its frequency upward in ancestral Caucasian populations.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Testicular CFTR splice variants in patients with congenital absence of the vas deferens.

The involvement of the five thymidine (5T) variant in intron 8 of the cystic fibrosis membrane regulator (CFTR) gene in congenital bilateral absence of the vas deferens (CBAVD) phenotype has been extensively demonstrated. This variant leads to alternative splicing of the CFTR gene which results in a wild-type transcript and one without exon 9. Little is known about expression of the CFTR gene in the testis. We analysed the level of the aberrantly spliced transcripts in testicular biopsies and correlated it with disease expression. Quantitative RT-PCR analysis in testicular biopsies from control and CBAVD patients showed a correlation between the length of the IVS8-6(T) n tract and the level of alternatively spliced transcripts. Results from histological analysis also suggest an involvement of the alternative transcript in the spermatogenic status of patients, leading to a decreased number of mature sperm forms in the tubule.

Alternative Splicing↗
PubMed1998

A patient with autistic disorder and a 20/22 chromosomal translocation.

The case history of a 3-year-old boy without speech and who met 10 criteria of an autistic condition (DSM-IV) (American Psychiatric Association 1994) is reported. Psychometric evaluation, excluding the verbal scale, resulted in an IQ score of 56. The cytogenetic study showed a 20/22 translocation and an interstitial deletion within the region 22q11: 45,XY, -22, +der(20), t(20;22) (q13.3;q11.2), which was confirmed by fluorescence in situ hybridisation (FISH). Although deletions at 22q11 are responsible for the DiGeorge syndrome; clinical, metabolic, and neurological image studies of the patient were inconsistent with this syndrome. In the clinical examination the patient presented with a mildly dysmorphic facies, pectus excavatum, and a short thumb. A 99mTc HMPAO brain perfusion SPECT showed a hypoperfusion of the left temporoparietal cortex. As there have been no previous reports of autistic patients with abnormalities involving both chromosomes 20 and 22, these findings merit some discussion either as a possible cause of autism or as accompanying factors.

Autistic Disorder↗
PubMed1998

Role of UEV-1, an inactive variant of the E2 ubiquitin-conjugating enzymes, in in vitro differentiation and cell cycle behavior of HT-29-M6 intestinal mucosecretory cells.

By means of differential RNA display, we have isolated a cDNA corresponding to transcripts that are down-regulated upon differentiation of the goblet cell-like HT-29-M6 human colon carcinoma cell line. These transcripts encode proteins originally identified as CROC-1 on the basis of their capacity to activate transcription of c-fos. We show that these proteins are similar in sequence, and in predicted secondary and tertiary structure, to the ubiquitin-conjugating enzymes, also known as E2. Despite the similarities, these proteins lack a critical cysteine residue essential for the catalytic activity of E2 enzymes and, in vitro, they do not conjugate or transfer ubiquitin to protein substrates. These proteins constitute a distinct subfamily within the E2 protein family and are highly conserved in phylogeny from yeasts to mammals. Therefore, we have designated them UEV (ubiquitin-conjugating E2 enzyme variant) proteins, defined as proteins similar in sequence and structure to the E2 ubiquitin-conjugating enzymes but lacking their enzymatic activity (HW/GDB-approved gene symbol, UBE2V). At least two human genes code for UEV proteins, and one of them, located on chromosome 20q13.2, is expressed as at least four isoforms, generated by alternative splicing. All human cell types analyzed expressed at least one of these isoforms. Constitutive expression of exogenous human UEV in HT-29-M6 cells inhibited their capacity to differentiate upon confluence and caused both the entry of a larger proportion of cells in the division cycle and an accumulation in G2-M. This was accompanied with a profound inhibition of the mitotic kinase, cdk1. These results suggest that UEV proteins are involved in the control of differentiation and could exert their effects by altering cell cycle distribution.

Amino Acid Sequence↗
PubMed1998

Uncloned expanded CAG/CTG repeat sequences in autosomal dominant cerebellar ataxia (ADCA) detected by the repeat expansion detection (RED) method.

In some neurodegenerative diseases, genetic anticipation correlates with expansions of the CAG/CTG repeat sequence above the normal range through the generations of a pedigree. Among these neurodegenerative diseases are late onset autosomal dominant cerebellar ataxias (ADCA). ADCA are genetically heterogeneous disorders with different cloned genes for spinocerebellar ataxia type 1 (SCA1), type 2 (SCA2), type 3 or Machado-Joseph disease (SCA3/MJD), and type 6 (SCA6). Another related dominant ataxia, dentatorubral-pallidoluysian atrophy (DRPLA), also shows CAG/CTG repeat expansions. Genetic anticipation has been reported for all of them except for the recently cloned SCA6 gene. Other, as yet undetected SCA genes may show the same features. We have used the repeat expansion detection (RED) method to detect repeat expansions directly in DNA samples from ADCA patients not resulting from known genes. Our sample consists of 19 affected index cases, corresponding to 52.8% of our ADCA families without CAG/CTG repeat expansions in the SCA1, SCA2, SCA3/MJD, SCA6, or DRPLA genes. Eighty-nine percent of the index cases had expansions of a CAG/CTG sequence greater than 40 repeats by RED, while these were observed in only 26.9% of 78 healthy subjects from the general population (p < 0.0001). The distribution of RED fragments in controls and ADCA patients also shows significant differences with the Mann-Whitney U test (U = 376.5, p = 0.0007). Moreover, there was a significant inverse correlation between the size of expansion and the age of onset (r = -0.54, p = 0.018). These results show CAG/CTG repeat expansions of over 40 repeats in our sample of ADCA families not resulting from known SCA genes.

Adult↗
PubMed1998

Molecular cloning, expression, and chromosomal localization of a ubiquitously expressed human 6-phosphofructo-2-kinase/ fructose-2, 6-bisphosphatase gene (PFKFB3).

We report the identification of a human 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase gene (PFKFB3) isolated from a human fetal brain cDNA library. The gene was localized to 10p15-->p14 by fluorescence in situ hybridization. The entire cDNA (4,322 bp) codes for a polypeptide of 520 amino acid residues (molecular weight, 59.571 kDa). Structural analysis showed the presence of a kinase domain located at the amino terminus and a bisphosphatase domain at the carboxy terminus, characteristic of previously described 6-phosphofructo-2-kinase/fructose 2, 6-bisphosphatase isozymes. In addition, a phosphorylation site for cAMP-dependent protein kinase was found at the carboxy terminus. Northern blot analysis showed the presence of a unique 4.8-kb mRNA expressed in the different tissues studied. In mammalian COS-1 cells, this cDNA drives the expression of an active isozyme. Taken together, these results identify the presence of a gene coding for a human 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase isozyme which is ubiquitously expressed.

Animals↗
PubMed1997

Reduced steady-state levels of mitochondrial RNA and increased mitochondrial DNA amount in human brain with aging.

The contribution of the mitochondrial genetic system in the degenerative processes of senescence remains unclear. This study deals with age-related changes in brain mtDNA expression in humans. Brain tissue from the frontal lobe cortex was obtained from autopsy of 13 humans aged between 21 and 84 years. No structural changes were detected in mtDNA, increased mtDNA content and reduced steady-state level of mitochondrial transcripts and transcription ratio (mtRNA/mtDNA) were associated with aging. These findings suggest that the increase of the mtDNA levels could be considered as an inefficient compensatory mechanism to maintain the normal levels of mtRNA transcripts. This unbalanced mitochondrial condition could play a role in the process of senescence in human brain.

Adult↗
PubMed1997

Cosmid contig and transcriptional map of three regions of human chromosome 21q22: identification of 37 novel transcripts by direct selection.

Human chromosome 21 is associated with many disorders, including Down syndrome (DS). In an effort to identify genes involved in brain development or function and therefore implicated in the mental retardation associated with DS, we chose YACs from three regions of chromosome 21: a region within the so-called "Down syndrome critical region," a region proximal to it, and one distal to it. We made cosmid libraries from these YACs and generated high-resolution physical maps by constructing cosmid contigs. These are the first cosmid contigs on chromosome 21 outside the critical region. The cosmids were used for direct selection of cDNAs to isolate chromosome 21 expressed sequences. We have isolated 45 nonredundant partial cDNAs and mapped these back to the cosmid contigs. We isolated 3 nonoverlapping portions of DSCR1 and a part of GIRK2 and identified 3 nonoverlapping partial cDNAs with similarity to the rat Dyrk gene, which turned out to be the human homologue (MNB) of the Drosophila minibrain gene. Twelve sequences had matches with either STS or EST entries in the databases, including a chromosome 21 EST, a chromosome 21 STS, and 6 unmapped expressed sequence entries. Only 1 sequence resulted in a match with a protein entry. The remaining 25 sequences revealed no similarity to any database entry. All of these partial cDNAs are expressed as determined by Northern blotting or by RT-PCR.

Animals↗
PubMed1997

Rapid sizing of polymorphic microsatellite markers by capillary array electrophoresis.

Genetic mapping and DNA sequencing projects could potentially be completed more rapidly by using capillary array electrophoresis (CAE) systems running 48-96 capillaries simultaneously. Currently, multiplex polymerase chain reaction (PCR) and multicolor fluorescent dye-labeling strategies are used to generate DNA profiles containing 18-24 genotypes per sample. By using 4-color fluorescence detection and these multiplex PCR strategies, a CAE system has the capacity to generate up to 5.5 million genotypes per year. CAE offers extremely fast, high-resolution separation of DNA and more automated sample processing than conventional systems because the labor-intensive slab-gel pouring and sample-loading steps are eliminated. We used a prototype CAE system in an ongoing linkage analysis study of inherited deafness in Mediterranean families. CA-repeat markers linked to deafness susceptibility genes on chromosomes 7, 11 and 13 were analyzed and DNA profiles generated which contain 6 markers per color. Fragment sizes of over 28,000 short tandem repeat alleles and 3200 CA-repeat alleles have been determined by CAE. An average sizing precision of +/- 0.12 base pairs (bp) for fragments up to 350 bp was realized in 1-h runs. In addition, a versatile non-denaturing matrix was used to separate DNA sizing standards, restriction digests, and multiplex PCR samples. Application of this matrix to Duchenne muscular dystrophy exon deletion screening is also described. These CAE approaches should facilitate rapid genotyping of microsatellite markers and subsequent identification of disease-causing mutations.

Base Sequence↗
PubMed1997

Genomic organization, alternative splicing, and expression patterns of the DSCR1 (Down syndrome candidate region 1) gene.

Down syndrome is a major cause of mental retardation and congenital heart defects and is due to the presence of three copies of human chromosome 21 in the affected individual. We have identified a gene, DSCR1 (HGMW-approved symbol), from the region 21q22.1-q22.2, which is highly expressed in human fetal brain and adult heart. Structural features of the conceptual protein encourage us to propose involvement of DSCR1 in the regulation of transcription and/or signal transduction. Higher expression of RNA in the brains of young rats compared to adults suggests a possible role for the gene in the development of the central nervous system. We have determined the genomic organization of DSCR1 and identified three additional alternative first exons by RACE and cDNA library screening. DSCR1 spans nearly 45 kb of genomic DNA and comprises seven exons, four of which (exons 1-4) are alternative first exons. All the exons are flanked by splice junctions that conform to the consensus AG-GT motif. We have studied the expression patterns of the alternative first exons. Exon 2 was detected in fetal brain and liver by RT-PCR. Both exons 1 and 4 were differentially expressed in fetal brain, lung, liver, and kidney and in all adult tissues tested by Northern analysis with two notable exceptions: exon 1 was not detected in adult kidney and exon 4 was not found in adult brain. The high level of expression of exon 1 in fetal brain suggests that this alternative form of DSCR1 has an important role in brain development. This information should help us to understand the possible relationship of DSCR1 with Down syndrome and aid in the development of animal models.

Alternative Splicing↗
PubMed1997

[Molecular analysis of the IT15 gene in 79 Spanish families with Huntington's disease: diagnostic confirmation and presymptomatic diagnosis].

BACKGROUND: Huntington's disease (HD) is a neurodegenerative disorder with late age of onset, caused by (CAG), expansion in the IT15 gene. We present here the results of IT15 gene study in Spanish families in order to show the usefulness of diagnosis, genetic counseling and clinical-genetic correlation in Spanish population. PATIENTS AND METHODS: We have studied the number of (CAG)n repeats in the IT15 gene by PCR analysis in 137 individuals from 79 Spanish families with HD. RESULTS: The number of (CAG)n repeats in HD chromosomes varied from 35 to 85, while the range for the normal chromosomes was from 13 to 31. In four juvenile cases the number of (CAG)n repeats was above 50. In three of these cases the transmission was paternal. The (CAG)n expansion was demonstrated in 98.3% of the cases. We established the diagnosis in 15 uncertain clinical diagnosis. We made a presymptomatic diagnosis after psychological-psychiatric evaluation in 50 HD at risk individuals. We showed an inverse correlation between the number of (CAG)n repeats and the age at onset of the disease. CONCLUSIONS: The (CAG)n repeats study in the IT15 gene in Spanish populations allows the confirmation of diagnosis of HD as well as presymptomatic testing enabling the genetic counseling. There is an inverse correlation between the age of onset of the disease and the number of (CAG)n repeats in the IT15 gene.

Adolescent↗
PubMed1997

Absence of linkage between type III protein S deficiency and the PROS1 and C4BP genes in families carrying the protein S Heerlen allele.

To elucidate the molecular basis of hereditary protein S (PS) deficiency and, in particular, type III or free PS deficiency, the allelic distribution and segregation patterns of the PS gene (PROS1) polymorphisms P626A/G and S460P (PS Heerlen) have been analyzed in a group of 45 proposita suffering from type I or type III PS deficiency. No differences between patients and controls were found in the frequency of the P626A/G alleles. By contrast, the frequency of the PS Heerlen allele in the group of patients with type III PS deficiency (9 of 46 chromosomes, P = .196) was significantly higher (P < .001) than in the control group (1 of 300 chromosomes, P = .003). The A allele of P626A/G was always associated with the P allele of S460P. However, this haplotype did not co-segregate with the type III PS-deficient phenotype in 3 of the families. Furthermore, multipoint linkage analysis excluded the whole PROS1 gene in 1 of these families, which is in agreement with the absence of mutations in the PROS1 gene, as determined by sequence analysis. Finally, linkage analysis with 4 microsatellite markers linked to the C4BPB and C4BPA loci also excluded these two genes. From these results we conclude that, at least in some families, the molecular basis of type III PS deficiency is not due to the Mendelian inheritance of a single defect in the PROS1 or in the C4BP genes.

Adult↗
PubMed1997

SSCP analysis: a blind sensitivity trial.

Studies of the sensitivity of SSCP analysis usually have been performed under conditions contrary to the rules of quality control trials and have produced widely different results. We have performed a blind trial of the sensitivity of SSCP analysis for the detection of mutations in fragments up to 500 bp in length under a fixed single set of electrophoretic conditions. The mutation detection rate was 84%. In addition, we have identified a second mutation in nine samples. All these mutations are polymorphisms, including a novel polymorphism 1248 + 52T/C first reported in the present work.

Cystic Fibrosis Transmembrane Conductance Regulato↗
PubMed1997

Geographic distribution and regional origin of 272 cystic fibrosis mutations in European populations. The Biomed CF Mutation Analysis Consortium.

The geographic distribution of 272 cystic fibrosis (CF) mutations has been studied by assessing the origin of 27,177 CF chromosomes from 29 European countries and three countries from the North of Africa. The most common mutations are delta F308 (66.8%), G542X (2.6%), N1303K (1.6%), G551D (1.5%) and W1282X (1.0%). The delta F508 mutation has the highest frequency in Denmark (87.2%) and the lowest in Algeria (26.3%). Mutation G542X is common in the Mediterranean countries, with a mean frequency of 6.1%. N1303K is found in most of the western and Mediterranean countries and has the highest frequency in Tunisia (17.2%). The wide distribution of these mutations suggests an ancient origin. G551D is common in north-west and central Europe, but is uncommon in other parts of Europe. W1282X has the highest frequency in Israel (36.2%), being also common in most Mediterranean countries and north Africa. Seventeen mutation have frequencies between 0.1 and 0.9%, 1717-1G-->A (0.83%), R553X (0.75%), R1162X (0.51%), 621 + 1G-->T (0.54%) and 2183AA-->G (0.36%), being the most common ones. Some mutations reach relatively high frequencies in some extended geographic regions, such as mutation 394delTT in northern Europe (1.1-28.8%), R117H in northwestern Europe (1.3-3.0%), R553X in central Europe (1.1-24.4%), 1717-1G-->A in Belgium and France (1.1-5.3%), and 2183AA-->G in Italy and Greece (3.2%). Other mutations are only common in small regions: T338I (Sardinia), 711 + 1G-->T (Tunisia), R1162X (Algeria and north of Italy), 1609delCA (east of Spain), 1811 + 1.6kbA-->G (southeastern Spain), R1066C (Portugal), S549R (Algeria), R334W (Crete), 621 + 1G-->T (Central Greece), 3849 + 10kbC-->T (Israel), 2789 + 5G-->A (south of Greece), 451 + 1G--A (Israel), R347P (south of Bulgaria), 1677delTA (south of Bulgaria and Turkey), G85E (south of Greece), R347H (Turkey), 3905insT (Switzerland), 1078delT (Brittany), 1898 + 1G-->A (Wales), A455E (The Netherlands), delta I507 (Brittany), 3659delC (Sweden) and R560T (northern Ireland). Most of these mutations must have an origin and diffusion in the specific European population subgroup. Overall 55 mutations are common in one or several countries or regions of Europe and 217 mutations are rare with relative frequencies of lower than 1% in any of these regions and countries. This information might facilitate mutation analysis of CF in the different regions of Europe.

Africa, Northern↗