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Biomedical subjects

C Ayuso

Publications and source records attributed to C Ayuso.

At least 73 records · Page 4Linked to original sources
PubMed1999

Identification of 9 novel FBN1 mutations in German patients with Marfan syndrome.

We report 9 new mutations in German patients presenting with classical Marfan syndrome. All mutations occur in exons with calcium-binding (cb) epidermal growth factor-like (EGF) domains. Five mutations are missense involving exons 12, 27, 30, 44, and 52 with the resultant substitution of cysteine by phenylalanine (C504F), cysteine by tyrosine (C1129Y), tyrosine by cysteine (Y1261C), cysteine by serine (C1833S), and cysteine by tyrosine (C2142Y), respectively. The other four mutations are single base deletions in exons 39, 43, 48, and 58, at nucleotide A4826, C5311, T6018, and A7291, respectively, each resulting in frameshift with premature termination. Four mutations were detected in sporadic cases and are likely to be de novo.

Adult↗
PubMed1999

Identification of three novel mutations in the MYO7A gene.

Three new mutations in the myosin VIIA gene involved in the pathogenesis of Usher syndrome type Ib are reported. These mutations are K1080X in exon 25, E1170K in exon 28, and Y1719C in exon 37. It is presumed that these mutations are involved in the Usher syndrome Ib phenotype.

Base Sequence↗
PubMed1999

Genomic cloning, structure, expression pattern, and chromosomal location of the human SIX3 gene.

The Drosophila gene sine oculis (so) is a nuclear homeoprotein that is required for eye development. Homologous genes to so, denoted SIX genes, have been found in vertebrates. Among the SIX genes, SIX3 is considered to be the functional homologue of so. To provide insight into the potential implications of SIX3 in human ocular malformations, we have cloned and characterized the human SIX3 gene. In human eye, SIX3 produces a 3-kb transcript that codes for a 332-amino-acid polypeptide that is virtually identical to its mouse and chick homologues. Expression of SIX3 was detected in human embryos as early as 5-7 weeks of gestation and found to be maintained in the eye throughout the entire period of fetal development. At 20 weeks of gestation, expression of SIX3 in the human retina was detected in the ganglion cells and in cells of the inner nuclear layer. The human SIX3 gene spans 4.4 kb of genomic DNA and is split in two exons separated by a 1659-bp intron. SIX3 was mapped to human chromosome 2p16-p21, between the genetic markers D2S119 and D2S288. Interestingly, the map position of human SIX3 overlaps the locations of two dominant disorders with ocular phenotypes that have been assigned to this chromosomal region, holoprosencephaly type 2 and Malattia Leventinese.

Amino Acid Sequence↗
PubMed1999

Segregation of digital number with partial monosomy or trisomy of 13q in familial 5;13 translocation.

It has been postulated that the deletion of band 13q22 may be associated with digital malformations, especially thumb and big toe anomalies. We report a family where the mother is carrying a balanced translocation between chromosomes 5p15 and 13q22. The offspring have a specific and well-defined phenotype depending on which is the unbalanced chromosome in the karyotype. When a partial trisomy of 13q22-->qter is present, the fetuses have polydactyly in the four limbs, and when the fetus is carrying a partial monosomy of this portion, an oligodactyly in all members can be observed.

Chromosome Segregation↗
PubMed1999

Prenatal diagnosis on fetal cells obtained from maternal peripheral blood: report of 66 cases.

The potential use of fetal cells circulating in maternal blood for a non-invasive prenatal diagnosis has been widely described. Several authors have developed different methods for the enrichment of fetal cells from maternal peripheral blood. The aim of this study was to make a practical valuation of this new prenatal diagnosis technique, using those methods described as efficient and easy to carry out in a prenatal diagnosis unit. These methods consist of the double-density gradient and the positive selection by magnetic activated cell sorting (MACS) of the fetal erythroblasts, and the posterior study of the cells applying the FISH interphasic technique. Once the technique was ready, we obtained results from the study of 66 venous blood samples from women coming for prenatal diagnosis. Using a specific staining for fetal haemoglobin, fetal cells were identified in 63 cases. Fetal sex was well determined in 56 cases, 23 females and 33 males; in 7 cases the sex determination failed. All the aneuploidies found in a previous prenatal diagnosis were confirmed.

Blood Cells↗
PubMed1999

Atypical retroperitoneal fibrosis: MRI findings.

A case of retroperitoneal fibrosis with an unusual perirenal involvement diagnosed at MR imaging is reported. Other conditions, such as metastatic disease or lymphoma, may be considered especially when the initial presentation is not typical. Imaging modalities in this condition are discussed.

Diagnosis, Differential↗
PubMed1999

Mutation analysis of the RPGR gene reveals novel mutations in south European patients with X-linked retinitis pigmentosa.

The RPGR (retinitis pigmentosa GTPase regulator) gene has been shown to be mutated in 10-20% of patients with X-linked retinitis pigmentosa (XLRP), a severe form of inherited progressive retinal degeneration. A total of 29 different RPGR mutations have been identified in northern European and United States patients. We have performed mutation analysis of the RPGR gene in a cohort of 49 southern European males affected with XLRP. By multiplex SSCA and automatic direct sequencing of all 19 RPGR exons, seven different and novel mutations were identified in eight of the 49 families; these include three splice site mutations, two microdeletions, and two missense mutations. RNA analysis showed that the three splice site defects resulted in the generation of aberrant RPGR transcripts. Six of these mutations were detected in the conserved amino-terminal region of RPGR protein, containing tandem repeats homologous to the RCC1 protein, a guanine nucleotide-exchange factor for Ran-GTPase. Several exonic and intronic sequence variations were also detected. None of the RPGR mutations reported in other populations were identified in our series. Our results are consistent with the notions of heterogeneity and minority causation of XLRP by mutations in RPGR in Caucasian populations.

Base Sequence↗
PubMed1999

Characterization of a germline mosaicism in families with Lowe syndrome, and identification of seven novel mutations in the OCRL1 gene.

The oculocerebrorenal syndrome of Lowe (OCRL) is an X-linked disorder characterized by major abnormalities of eyes, nervous system, and kidneys. Mutations in the OCRL1 gene have been associated with the disease. OCRL1 encodes a phosphatidylinositol 4, 5-biphosphate (PtdIns[4,5]P2) 5-phosphatase. We have examined the OCRL1 gene in eight unrelated patients with OCRL and have found seven new mutations and one recurrent in-frame deletion. Among the new mutations, two nonsense mutations (R317X and E558X) and three other frameshift mutations caused premature termination of the protein. A missense mutation, R483G, was located in the highly conserved PtdIns(4,5)P2 5-phosphatase domain. Finally, one frameshift mutation, 2799delC, modifies the C-terminal part of OCRL1, with an extension of six amino acids. Altogether, 70% of missense mutations are located in exon 15, and 52% of all mutations cluster in exons 11-15. We also identified two new microsatellite markers for the OCRL1 locus, and we detected a germline mosaicism in one family. This observation has direct implications for genetic counseling of Lowe syndrome families.

Amino Acid Sequence↗
PubMed1998

[Usefulness of ultrasonography and computerized tomography in predicting resectability of pancreatic carcinoma].

BACKGROUND: Surgical resection is the only curative treatment of pancreatic carcinoma (PC). An accurate assessment of the extension of PC is mandatory to select appropriate patients to this therapeutic option. This study was aimed at assessing the usefulness of abdominal ultrasonography (US) and computed tomography (CT) to establish tumoral staging and to predict tumor resectability. PATIENTS AND METHODS: Between January 1990 and December 1995, 84 PC patients were submitted to surgical procedures (potentially curative resection in 30%, biliodigestive anastomosis in 51% and exploratory laparotomy in 13%). Preoperative staging was carried out by means of abdominal US and/or CT. Definitive staging was established according to surgical findings, using the TNM classification. RESULTS: Accuracy of preoperative evaluation with regard to tumoral staging was 65%, being underestimated in 29 (35%) patients. This underestimation was mainly due to lesions in stage I. In addition, preoperative staging predicted tumor unresectability with a 50% sensitivity and a 83% specificity. CONCLUSIONS: US and CT have a good specificity in the staging and unresectability prediction of pancreatic cancer. However, their usefulness is limited by their low sensitivity.

Aged↗
PubMed1998

Mutation of a gene encoding a protein with extracellular matrix motifs in Usher syndrome type IIa.

Usher syndrome type IIa (OMIM 276901), an autosomal recessive disorder characterized by moderate to severe sensorineural hearing loss and progressive retinitis pigmentosa, maps to the long arm of human chromosome 1q41 between markers AFM268ZD1 and AFM144XF2. Three biologically important mutations in Usher syndrome type IIa patients were identified in a gene (USH2A) isolated from this critical region. The USH2A gene encodes a protein with a predicted size of 171.5 kilodaltons that has laminin epidermal growth factor and fibronectin type III motifs; these motifs are most commonly observed in proteins comprising components of the basal lamina and extracellular matrixes and in cell adhesion molecules.

Amino Acid Sequence↗
PubMed1998

[The Pro347Leu mutation of the rhodopsin gene in a Spanish family with autosomal dominant pigmentary retinosis].

We present a Spanish family affected with autosomal dominant pigmentary retinosis in which we have identified the mutation responsible for the disease (Pro347Leu) within the rhodopsin (RHO) gene. Complete ophthalmological and electrophysiological studies were performed in 14 members of this family. The molecular study, performed by SSCP analysis of the 5 exon and the promotor region of the rhodopsin gene, direct sequentiation and restriction analysis with the enzyme Mspl, showed a C-->T change in the second base of 347 codon of RHO gene. This mutation predicts a change of proline by leucine at this position. Every patient with the mutation showed a phenotype of diffuse, early onset and severe pigmentary retinosis with a little intrafamiliar variation. The Pro347Leu mutation, that has been very frequently described among all the populations, has been identified as a cause of RP in an Spanish family.

Adolescent↗
PubMed1998

Residual splenic function after laparoscopic splenectomy: a clinical concern.

OBJECTIVE: To document the existence of residual splenic function after laparoscopic splenectomy in a series of 48 patients. DESIGN: A noncomparative descriptive case series. SETTING: A tertiary care center. PATIENTS: A series of 9 patients without clinical improvement after laparoscopic splenectomy of 48 consecutive patients undergoing laparoscopic splenectomy for several hematologic disorders after a mean follow-up of 16 months (range, 1-40 months). INTERVENTIONS: A computed tomographic scan and technetium Tc 99m sodium pertechnetate heat-damaged red blood cell scintigraphy were performed for patients with partial (platelet count <100x10(9)/L) or total (platelet count <50x10(9)/L) failure of improvement. MAIN OUTCOME MEASURE: Evidence of residual splenic tissue by image diagnosis. RESULTS: The condition of 9 of the 48 patients failed to improve after laparoscopic splenectomy. Six patients experienced a total failure of improvement and 3 experienced a partial failure of improvement (1 patient had human immunodeficiency virus-related thrombocytopenia and 8 had idiopathic thrombocytopenic purpura). Three patients had residual splenic function, which was revealed by scintigraphy. The results of a computed tomographic scan showed an accessory spleen in one patient and splenic implants in splenic fossa in another patient. CONCLUSION: Laparoscopic splenectomy has a promising role in the management of hematologic diseases requiring splenectomy, but it requires exquisite care to avoid parenchymal rupture and cell spillage and to avoid leaving accessory spleens, which can lead to the failure of surgical treatment.

Adolescent↗
PubMed1998

Novel mutations in the TIGR gene in early and late onset open angle glaucoma.

A gene for juvenile onset, open angle glaucoma (JOAG) has been localized to chromosome 1q21-31 in several families. Mutations in the trabecular meshwork-induced glucocorticoid response protein (TIGR) gene, which maps to this region, recently have been found in families segregating both JOAG and a later onset form of primary open angle glaucoma (POAG). We have analysed the TIGR gene in two families; one Spanish family segregating autosomal dominant JOAG and an Irish family with a later onset form of autosomal dominant POAG. We have found a G-T transversion in the first base of codon 426 in all affected members of the Spanish family, which results in a valine to phenylalanine amino acid substitution. We have also found a G-A transition at the first base of codon 367 that segregates through all but one branch of the Irish family and results in a glycine to arginine amino acid substitution. Members of this family that carry the Gly367Arg change also share a common haplotype that is neither present in any of the unaffected members of the family, nor in the branch that does not segregate the mutation. Identification of further mutations in the TIGR gene increases its importance in the etiology of open angle glaucoma.

Adult↗
PubMed1998

Novel germline p16(INK4) allele (Asp145Cys) in a family with multiple pancreatic carcinomas. Mutations in brief no. 148. Online.

As part of a search for causative genes of familial pancreatic carcinoma, the p16 genes were sequenced in members of 21 families with a phenotype of familial pancreatic carcinoma (2 or more first degree relatives affected). One family was found in which members carried a novel p16 allele with a G to T transversion at position 451, creating a missense amino acid change at codon 145 (Asp to Cys) and possibly disrupting the donor splice site of the exon 2/3 boundary. This coding change is not a known polymorphism, and occurs at a codon position in which another missese/splicing change has been shown to be linked to familial melanoma/pancreas cancer.

Alleles↗
PubMed1998

Spectrum of mutations and sequence variants in the FALDH gene in patients with Sjögren-Larsson syndrome.

The gene encoding the human fatty aldehyde dehydrogenase (FALDH) is located on 17p11.2, causing Sjögren-Larsson syndrome (SLS) when mutated. SLS is an autosomal recessive disorder characterized by a combination of mental retardation, congenital ichthyosis, and spastic di- or tetraplegia. We report here on studies of 16 SLS families from Europe and the Middle East, which resulted in identification of 11 different mutations. The spectrum of mutations characterized in the present study are five nucleotide substitutions resulting in amino acid changes, five frameshift mutations introducing a stop codon, and one in-frame deletion with insertion at the same position. We also observed silent sequence variants in the FALDH gene and a base pair substitution in exon 5 that alters aspartic acid to asparagine, all of which are considered polymorphisms.

Aldehyde Oxidoreductases↗
PubMed1998

Detection of a novel Cys628STOP mutation of the myosin VIIA gene in Usher syndrome type Ib.

A Spanish family with three Usher I syndrome-affected members was linked to markers located on chromosome 11q. A search for mutations on the myosin VIIA gene revealed a novel mutation (Cys628STOP) on exon 16 segregating with the disorder in a homozygous state. This nonsense mutation could be responsible for the disease since it leads to a truncated protein that presumably has no function.

Codon, Terminator↗