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1.
J Med Genet ; 47(4): 236-41, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19858128

RESUMEN

Bardet-Biedl syndrome (BBS) is a ciliopathy with pleiotropic effect that manifests primarily as renal insufficiency, polydactyly, retinal dystrophy and obesity. The current phenotype-genotype correlation is insufficient to predict the likely causative mutation that makes sequencing of all 14 BBS genes an often necessary but highly complicated way to identify the underlying genetic defect in affected patients. In this study, homozygosity mapping is shown as a robust approach that is highly suited for genetically heterogeneous autosomal recessive disorders in populations in which consanguinity is prevalent. This approach allowed us to quickly identify seven novel mutations in seven families with BBS. Some of these mutations would have been missed by unguided routine sequencing, which suggests that missed mutations in known BBS genes could be more common than previously thought. This study, the largest to date on Saudi BBS families, also revealed interesting phenotypic aspects of BBS, including the first report of non-syndromic retinitis pigmentosa as a novel BBS phenotype.


Asunto(s)
Síndrome de Bardet-Biedl/genética , Consanguinidad , Análisis Mutacional de ADN/métodos , Adolescente , Adulto , Animales , Síndrome de Bardet-Biedl/diagnóstico , Secuencia de Bases , Niño , Preescolar , Mapeo Cromosómico , Femenino , Homocigoto , Humanos , Masculino , Proteínas Asociadas a Microtúbulos , Datos de Secuencia Molecular , Análisis de Secuencia por Matrices de Oligonucleótidos , Linaje , Proteínas/genética , Alineación de Secuencia
2.
Am J Med Genet A ; 149A(6): 1219-23, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19449432

RESUMEN

Peroxisomal biogenesis disorders represent a group of genetically heterogeneous conditions that have in common failure of proper peroxisomal assembly. Clinically, they are characterized by a spectrum of dysmorphia, neurological, liver, and other organ involvement. To date, mutations in 13 PEX genes encoding peroxins have been identified in patients with peroxisomal biogenesis disorders. Mutations in PEX13, which encodes peroxisomal membrane protein PEX13, are among the least common causes of peroxisomal biogenesis disorders with only three mutations reported so far. Here, we report on two infants whose clinical and biochemical profile was consistent with classical Zellweger syndrome and whose complementation analysis assigned them both to group H of peroxisomal biogenesis disorders. We show that they harbor two novel mutations in PEX13. One patient had a genomic rearrangement resulting in a 147 kb deletion that spans the whole of PEX13, while the other had an out-of-frame deletion of 14 bp. This represents the first report of a PEX13 deletion and suggests that further work is needed to examine the frequency of PEX13 mutations among Arab patients with peroxisomal biogenesis disorders.


Asunto(s)
Mutación del Sistema de Lectura , Proteínas de la Membrana/deficiencia , Eliminación de Secuencia , Síndrome de Zellweger/genética , Secuencia de Bases , Fibroblastos/metabolismo , Fibroblastos/patología , Reordenamiento Génico , Prueba de Complementación Genética , Humanos , Lactante , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Síndrome de Zellweger/metabolismo
3.
Invest Ophthalmol Vis Sci ; 41(13): 4069-73, 2000 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11095597

RESUMEN

PURPOSE: Recent reports have shown that the autosomal dominant retinitis pigmentosa (adRP) phenotype linked to the pericentric region of chromosome 8 is associated with mutations in a gene designated RP1. Screening of the whole gene in a large cohort of patients has not been undertaken to date. To assess the involvement and character of RP1 mutations in adRP, the gene was screened in a panel of 266 unrelated patients of British origin and a Pakistani family linked to this locus. METHODS: Patients exhibiting the adRP phenotype were screened for mutations in the four exons of the RP1 gene by heteroduplex analysis and direct sequencing. Linkage of the Pakistani family was achieved using microsatellite markers. Polymerase chain reaction (PCR) products were separated by nondenaturing polyacrylamide gel electrophoresis. Alleles were assigned to individuals, which allowed calculation of LOD scores. Microsatellite marker haplotyping was used to determine ancestry of patients carrying the same mutation. RESULTS: In the 266 British patients and 1 Pakistani family analyzed, 21 loss-of-function mutations and 7 amino acid substitutions were identified, some of which may also be disease-causing. The mutations, many of which were deletion or insertion events, were clustered in the 5' end of exon 4. Most mutations resulted in a premature termination codon in the mRNA. Haplotype analysis of nine patients carrying an R677X mutation suggested that these patients are not ancestrally related. CONCLUSIONS: RP1 mutations account for 8% to 10% of the mutations in our cohort of British patients. The most common disease-causing mechanism is deduced to be one involving the presence of a truncated protein. Mutations in RP1 have now been described in adRP patients of four ethnically diverse populations. The different disease haplotype seen in the nine patients carrying the same mutation suggests that this mutation has arisen independently many times, possibly due to a mutation hot spot in this part of the gene.


Asunto(s)
Proteínas del Ojo/genética , Mutación , Retinitis Pigmentosa/genética , Estudios de Cohortes , Análisis Mutacional de ADN , Cartilla de ADN/química , Ligamiento Genético , Haplotipos , Análisis Heterodúplex , Humanos , Escala de Lod , Proteínas Asociadas a Microtúbulos , Fenotipo , Reacción en Cadena de la Polimerasa
4.
Mol Biotechnol ; 15(1): 1-10, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10911617

RESUMEN

Conserved sequence amplification (CSA) has been used to obtain sequence data for two glycosidase genes from the primitive eukaryote Tritrichomonas foetus. Few genes have been cloned from this organism, and there is little information concerning protein sequence. CSA is reliant on the use of database searches to identify short sequences of 3-9 amino acids conserved within a protein across a wide range of species. PCR primers are then constructed based on this sequence data and the DNA is amplified and sequenced. In the case of the beta-galactosidase gene, N-terminal amino acid sequence data were used to construct a primer that replaced the upstream primer to ensure the amplified product was related to beta-D-galactosidase. CSA was also applied to the gene encoding the enzyme beta-N-acetyl-D-glucosaminidase from T. foetus, but in this case a segment of DNA was amplified, which, if correct, should contain a third conserved motif. The products of the CSA were sequenced, and the data obtained were compared to data in the SwissProt database. The results obtained suggest that this approach is useful for the cloning of genes to obtain novel sequence data from organisms where little genetic information is available.


Asunto(s)
Clonación Molecular/métodos , Bases de Datos Factuales , Glicósido Hidrolasas/genética , Reacción en Cadena de la Polimerasa/métodos , Tritrichomonas foetus/genética , Acetilglucosaminidasa/genética , Secuencia de Aminoácidos , Animales , Secuencia Conservada , Datos de Secuencia Molecular , Homología de Secuencia de Aminoácido , Tritrichomonas foetus/enzimología , beta-Galactosidasa/genética
5.
Ann Hum Genet ; 72(Pt 1): 26-34, 2008 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17803723

RESUMEN

Retinitis pigmentosa (RP) is a group of retinal dystrophies characterised primarily by rod photoreceptor cell degeneration. Exhibiting great clinical and genetic heterogeneity, RP be inherited as an autosomal dominant (ad) and recessive (ar), X-linked (xl) and digenic disorder. RP25, a locus for arRP, was mapped to chromosome 6p12.1-q14.1 where several retinal dystrophy loci are located. A gene expressed in the retina, FAM46A, mapped within the RP25 locus, and computational data revealed its involvement in retinal signalling pathways. Therefore, we chose to perform molecular evaluation of this gene as a good candidate in arRP families linked to the RP25 interval. A comprehensive bioinformatic and retinal tissue expression characterisation of FAM46A was performed, together with mutation screening of seven RP25 families. Herein we present 4 novel sequence variants, of which one is a novel deletion within a low complexity region close to the initiation codon of FAM46A. Furthermore, we have characterised for the first time a coding tandem variation in the Caucasian population. This study reports on bioinformatic and moleculardata for the FAM46A gene that may give a wider insight into the putative function of this gene and its pathologic relevance to RP25 and other retinal diseases mapping within the 6q chromosomal interval.


Asunto(s)
Familia , Genes Recesivos , Repeticiones de Minisatélite/genética , Retinitis Pigmentosa/genética , Alelos , Secuencia de Bases , Estudios de Casos y Controles , Mapeo Cromosómico , Cromosomas Humanos Par 6 , Biología Computacional/métodos , Análisis Mutacional de ADN , Frecuencia de los Genes , Humanos , Intrones , Linaje , Polimorfismo de Nucleótido Simple , Retinitis Pigmentosa/patología , Eliminación de Secuencia , España
6.
Ann Hum Genet ; 72(Pt 4): 463-77, 2008 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-18510646

RESUMEN

A large scale bioinformatics and molecular analysis of a 34 Mb interval on chromosome 6q12 was undertaken as part of our ongoing study to identify the gene responsible for an autosomal recessive retinitis pigmentosa (arRP) locus, RP25. Extensive bioinformatics analysis indicated in excess of 110 genes within the region and we also noted unfinished sequence on chromosome 6q in the Human Genome Database, between 58 and 61.2 Mb. Forty three genes within the RP25 interval were considered as good candidates for mutation screening. Direct sequence analysis of the selected genes in 7 Spanish families with arRP revealed a total of 244 sequence variants, of which 67 were novel but none were pathogenic. This, together with previous reports, excludes 60 genes within the interval ( approximately 55%) as disease causing for RP. To investigate if copy number variation (CNV) exists within RP25, a comparative genomic hybridization (CGH) analysis was performed on a consanguineous family. A clone from the tiling path array, chr6tp-19C7, spanning approximately 100-Kb was found to be deleted in all affected members of the family, leading to a major refinement of the interval. This will eventually have a significant impact on cloning of the RP25 gene.


Asunto(s)
Mapeo Cromosómico , Cromosomas Humanos Par 6/genética , Retinitis Pigmentosa/genética , Biología Computacional , Análisis Mutacional de ADN , Eliminación de Gen , Ligamiento Genético , Genoma Humano , Humanos , Datos de Secuencia Molecular , Mutación , Hibridación de Ácido Nucleico , Linaje
7.
Mol Cell ; 8(2): 375-81, 2001 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-11545739

RESUMEN

We report mutations in a gene (PRPF31) homologous to Saccharomyces cerevisiae pre-mRNA splicing gene PRP31 in families with autosomal dominant retinitis pigmentosa linked to chromosome 19q13.4 (RP11; MIM 600138). A positional cloning approach supported by bioinformatics identified PRPF31 comprising 14 exons and encoding a protein of 499 amino acids. The level of sequence identity to the yeast PRP31 gene indicates that PRPF31 is also likely to be involved in pre-mRNA splicing. Mutations that include missense substitutions, deletions, and insertions have been identified in four RP11-linked families and three sporadic RP cases. The identification of mutations in a pre-mRNA splicing gene implicates defects in the splicing process as a novel mechanism of photoreceptor degeneration.


Asunto(s)
Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Empalme del ARN/genética , Retinitis Pigmentosa/genética , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Alelos , Secuencia de Aminoácidos , Animales , Cromosomas Humanos Par 19 , Clonación Molecular , Biología Computacional , Proteínas Fúngicas/química , Proteínas Fúngicas/fisiología , Ligamiento Genético , Humanos , Datos de Secuencia Molecular , Mutación/genética , Linaje , Mapeo Físico de Cromosoma , Alineación de Secuencia , Empalmosomas
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