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1.
Balkan J Med Genet ; 23(2): 25-34, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33816069

RESUMEN

Carriers of apparently balanced chromosomal rearrangements (ABCRs) have a 2-3-fold higher risk of carrying an abnormal phenotype, when compared to the average population. Apparently balanced chromosomal rearrangements can be imbalanced at the submicroscopic level, and changes in the gene structure, formation of a new chimeric gene, gain or loss of function of the genes and altered imprinting pattern may also affect the phenotype. Chromosomal microarray (CMA) is an efficient tool to detect submicroscopic imbalances at the breakpoints as well as in the whole genome. We aimed to determine the effectiveness of array-comparative genomic hybridization (aCGH) application in phenotypically affected cases with ABCRs at a single center from Turkey. Thirty-four affected cases (13 prenatal, 21 postnatal) carrying ABCRs were investigated with CMA. In postnatal series, ABCRs were familial in 7 and de novo in 14 cases. Seven de novo cases were imbalanced (in postnatal series 33.3% and in de novo cases 50.0%). Out of 13 prenatal cases, five were familial and eight were de novo in origin and two de novo cases were imbalanced (in 15.4% prenatal series and in 25.0% de novo cases). No cryptic imbalance was observed in familial cases. The anomaly rates with array studies ranged between 14.3-25.0% in familial and between 20.0-57.5% in de novo cases of postnatal series in the literature. Studies focused on prenatal ABCR cases with abnormal ultrasound findings are limited and no submicroscopic imbalance was reported in the cohorts. When de novo postnatal or prenatal results were combined, the percentage of abnormalities detected by CMA was 40.9%. Taking this contribution into consideration, all ABCRs should be investigated by CMA even if the fetal ultrasound findings are normal.

2.
Genet Couns ; 27(3): 385-392, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-30204968

RESUMEN

Some of the disorders of sex development (DSD), including 46, XX testicular DSD formerly called "XX maleness" and 46, XY DSD with partial or complete gonadal dysgenesis primarily affect the gonads. Genetic alterations in ten unrelated females with complete 46, XY gonadal dysgenesis (GD) were analyzed using an Array 2.7 M platform with whole genome coverage. The analysis result suggested that the most significant region maps to chromosome 8q24.3 which were previously reported by another independent study with a similar patient cohort and this region being probable candidate related to complete 46, XY GD.


Asunto(s)
Duplicación Cromosómica/genética , Cromosomas Humanos Par 8/genética , Trastornos del Desarrollo Sexual/genética , Disgenesia Gonadal 46 XY/genética , Testículo/anomalías , Mapeo Cromosómico , Estudios de Cohortes , Hibridación Genómica Comparativa , Trastornos del Desarrollo Sexual/diagnóstico , Femenino , Estudio de Asociación del Genoma Completo , Disgenesia Gonadal 46 XY/diagnóstico , Humanos , Cariotipificación , Polimorfismo Genético/genética , Turquía
3.
BMC Med Genet ; 16: 50, 2015 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-26188928

RESUMEN

BACKGROUND: Offspring of consanguineous couples are at increased risk of congenital disorders. The risk increases as parents are more closely related. Individuals that have the same degree of relatedness according to their pedigree, show variable genomic kinship coefficients. To investigate whether we can differentiate between couples with high- and low risk for offspring with congenital disorders, we have compared the genomic kinship coefficient of consanguineous parents with a child affected with an autosomal recessive disorder with that of consanguineous parents with only healthy children, corrected for the degree of pedigree relatedness. METHODS: 151 consanguineous couples (73 cases and 78 controls) from 10 different ethnic backgrounds were genotyped on the Affymetrix platform and passed quality control checks. After pruning SNPs in linkage disequilibrium, 57,358 SNPs remained. Kinship coefficients were calculated using three different toolsets: PLINK, King and IBDelphi, yielding five different estimates (IBDelphi, PLINK (all), PLINK (by population), King robust (all) and King homo (by population)). We performed a one-sided Mann Whitney test to investigate whether the median relative difference regarding observed and expected kinship coefficients is bigger for cases than for controls. Furthermore, we fitted a mixed effects linear model to correct for a possible population effect. RESULTS: Although the estimated degrees of genomic relatedness with the different toolsets show substantial variability, correlation measures between the different estimators demonstrated moderate to strong correlations. Controls have higher point estimates for genomic kinship coefficients. The one-sided Mann Whitney test did not show any evidence for a higher median relative difference for cases compared to controls. Neither did the regression analysis exhibit a positive association between case-control status and genomic kinship coefficient. CONCLUSIONS: In this case-control setting, in which we compared consanguineous couples corrected for degree of pedigree relatedness, a higher degree of genomic relatedness was not significantly associated with a higher likelihood of having an affected child. Further translational research should focus on which parts of the genome and which pathogenic mutations couples are sharing. Looking at relatedness coefficients by determining genome-wide SNPs does not seem to be an effective measure for prospective risk assessment in consanguineous parents.


Asunto(s)
Anomalías Congénitas/genética , Consanguinidad , Genes Recesivos , Genoma Humano/genética , Secuencia de Bases , Estudios de Casos y Controles , Femenino , Genotipo , Humanos , Masculino , Linaje , Polimorfismo de Nucleótido Simple , Análisis de Secuencia de ADN , Estadísticas no Paramétricas
4.
Clin Genet ; 87(1): 34-41, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-24716670

RESUMEN

Robinow Syndrome (RS), a rare skeletal dysplasia syndrome, is characterized by dysmorphic features resembling a fetal face, mesomelic limb shortening, hypoplastic external genitalia in males, and renal and vertebral anomalies. Both autosomal dominant and autosomal recessive patterns of inheritance have been reported. Since the description of autosomal dominant Robinow Syndrome (ADRS; OMIM 180700) in 1969 by Meinhard Robinow and colleagues, the molecular etiology remained elusive until only recently. WNT5A was proposed to be the candidate gene for ADRS, as mutations were found in two affected families, one of those being the originally described index family. We report three families with RS caused by novel heterozygous WNT5A mutations, which were confirmed in the first family by whole exome sequencing, and in all by Sanger sequencing. To our knowledge, this is the largest number of published families with ADRS in whom a WNT5A mutation was identified. Families 1 and 2 are the first cases showing de novo inheritance in the affected family members and thus strengthen the evidence for WNT5A as the causative gene in ADRS. Finally, we propose WNT5A mutation specificity in ADRS, which may affect interactions with other proteins in the Wnt pathway.


Asunto(s)
Anomalías Craneofaciales/genética , Anomalías Craneofaciales/patología , Enanismo/genética , Enanismo/patología , Deformidades Congénitas de las Extremidades/genética , Deformidades Congénitas de las Extremidades/patología , Modelos Moleculares , Fenotipo , Proteínas Proto-Oncogénicas/genética , Anomalías Urogenitales/genética , Anomalías Urogenitales/patología , Proteínas Wnt/genética , Secuencia de Bases , Exoma/genética , Frecuencia de los Genes , Genotipo , Humanos , Masculino , Datos de Secuencia Molecular , Linaje , Proteínas Proto-Oncogénicas/química , Análisis de Secuencia de ADN , Proteínas Wnt/química , Proteína Wnt-5a
5.
Hum Genet ; 132(8): 885-98, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23568615

RESUMEN

Nager syndrome (MIM #154400) is the best-known preaxial acrofacial dysostosis, mainly characterized by craniofacial and preaxial limb anomalies. The craniofacial abnormalities mainly consist of downslanting palpebral fissures, malar hypoplasia, micrognathia, external ear anomalies, and cleft palate. The preaxial limb defects are characterized by radial and thumb hypoplasia or aplasia, duplication of thumbs and proximal radioulnar synostosis. Haploinsufficiency of SF3B4 (MIM *605593), which encodes SAP49, a component of the pre-mRNA spliceosomal complex, has recently been identified as the underlying cause of Nager syndrome. In our study, we performed exome sequencing in two and Sanger sequencing of SF3B4 in further ten previously unreported patients with the clinical diagnosis of Nager syndrome, including one familial case. We identified heterozygous SF3B4 mutations in seven out of twelve patients. Four of the seven mutations were shown to be de novo; in three individuals, DNA of both parents was not available. No familial mutations were discovered. Three mutations were nonsense, three were frameshift mutations and one T > C transition destroyed the translation start signal. In three of four SF3B4 negative families, EFTUD2 was analyzed, but no pathogenic variants were identified. Our results indicate that the SF3B4 gene is mutated in about half of the patients with the clinical diagnosis of Nager syndrome and further support genetic heterogeneity for this condition.


Asunto(s)
Exoma/genética , Disostosis Mandibulofacial/genética , Mutación/genética , Precursores del ARN/genética , Proteínas de Unión al ARN/genética , Empalmosomas/genética , Adolescente , Adulto , Preescolar , Femenino , Estudios de Asociación Genética , Humanos , Lactante , Masculino , Disostosis Mandibulofacial/diagnóstico , Factores de Empalme de ARN
6.
Nat Genet ; 25(4): 423-6, 2000 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-10932187

RESUMEN

Robinow syndrome is a short-limbed dwarfism characterized by abnormal morphogenesis of the face and external genitalia, and vertebral segmentation. The recessive form of Robinow syndrome (RRS; OMIM 268310), particularly frequent in Turkey, has a high incidence of abnormalities of the vertebral column such as hemivertebrae and rib fusions, which is not seen in the dominant form. Some patients have cardiac malformations or facial clefting. We have mapped a gene for RRS to 9q21-q23 in 11 families. Haplotype sharing was observed between three families from Turkey, which localized the gene to a 4. 9-cM interval. The gene ROR2, which encodes an orphan membrane-bound tyrosine kinase, maps to this region. Heterozygous (presumed gain of function) mutations in ROR2 were previously shown to cause dominant brachydactyly type B (BDB; ref. 7). In contrast, Ror2-/- mice have a short-limbed phenotype that is more reminiscent of the mesomelic shortening observed in RRS. We detected several homozygous ROR2 mutations in our cohort of RRS patients that are located upstream from those previously found in BDB. The ROR2 mutations present in RRS result in premature stop codons and predict nonfunctional proteins.


Asunto(s)
Anomalías Múltiples/genética , Receptores de Superficie Celular/genética , Anomalías Múltiples/patología , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Secuencia de Bases , Mapeo Cromosómico , Cromosomas Humanos Par 9/genética , ADN/química , ADN/genética , Análisis Mutacional de ADN , Cara/anomalías , Salud de la Familia , Femenino , Genes Recesivos , Genotipo , Humanos , Deformidades Congénitas de las Extremidades/genética , Masculino , Repeticiones de Microsatélite , Datos de Secuencia Molecular , Mutación , Linaje , Proteínas Tirosina Quinasas Receptoras/genética , Receptores Huérfanos Similares al Receptor Tirosina Quinasa , Eliminación de Secuencia , Homología de Secuencia de Aminoácido , Sindactilia , Síndrome
7.
J Med Genet ; 47(4): 262-7, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19797195

RESUMEN

BACKGROUND: Bardet-Biedl syndrome (BBS) is primarily an autosomal recessive disorder characterised by the five cardinal features retinitis pigmentosa, postaxial polydactyly, mental retardation, obesity and hypogenitalism. In addition, renal cysts and other anomalies of the kidney and urinary tract can be present. To date, mutations in 12 BBS genes as well as in MKS1 and CEP290 have been identified as causing BBS. The vast genetic heterogeneity of BBS renders molecular genetic diagnosis difficult in terms of the time and cost required to screen all 204 coding exons. METHOD: Here, the use of genome-wide homozygosity mapping as a tool to identify homozygous segments at known BBS loci, in BBS individuals from inbred and outbred background, is reported. RESULTS: In a worldwide cohort of 45 families, causative homozygous mutations in 20 families were identified via direct exon sequencing. Eleven of these mutations were novel, thereby increasing the number of known BBS mutations by 5% (11/218). CONCLUSIONS: Thus, in the presence of extreme genetic locus heterogeneity, homozygosity mapping provides a valuable approach to the molecular genetic diagnosis of BBS and will facilitate the discovery of novel pathogenic mutations.


Asunto(s)
Síndrome de Bardet-Biedl/genética , Mutación , Secuencia de Aminoácidos , Secuencia de Bases , Mapeo Cromosómico/métodos , Estudios de Cohortes , Consanguinidad , Estudios de Asociación Genética , Genoma Humano , Homocigoto , Humanos , Datos de Secuencia Molecular , Fenotipo , Proteínas/genética
8.
J Med Genet ; 47(1): 30-7, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19574259

RESUMEN

BACKGROUND: Roberts syndrome (RBS) and SC phocomelia are caused by mutations in ESCO2, which codes for an acetyltransferase involved in the regulation of sister chromatid cohesion. Of 26 mutations described to date, only one missense mutation has been reported and all others are predicted to be truncating mutations. Genotype-phenotype analysis has been hampered by limited numbers of patients with clinical information available. OBJECTIVE: To provide unpublished clinical data for 31 patients with proven ESCO2 mutations and combine this series with previously reported clinical and mutation data on 18 cases. Methods Genotype-phenotype correlations and functional effects of two novel ESCO2 mutations were analysed. In situ hybridisation on human embryos at Carnegie stages 14, 17 and 21 was performed to study ESCO2 expression during development. RESULTS AND CONCLUSIONS: Using the cohort of 49 patients, the clinical criteria for RBS were delineated to include: growth retardation; symmetric mesomelic shortening of the limbs in which the upper limbs are more commonly and severely affected than the lower limbs; characteristic facies with microcephaly. The severity of malformations of the facies correlates with the severity of limb reduction. The occurrence of corneal opacities may be associated with specific mutations. Two new mutations, both in the ESCO2 acetyltransferase domain, are described and their acetylation effects in vitro demonstrated. In situ hybridisation on human embryos showed ESCO2 expression in the brain, face, limb, kidney and gonads, which corresponds to the structures affected in RBS.


Asunto(s)
Anomalías Múltiples/genética , Acetiltransferasas/genética , Proteínas Cromosómicas no Histona/genética , Anomalías Craneofaciales/genética , Discapacidades del Desarrollo/genética , Discapacidad Intelectual/genética , Codón/genética , Femenino , Expresión Génica , Variación Genética , Humanos , Lactante , Masculino , Mutación Missense , Fenotipo , Estructura Terciaria de Proteína/genética , Eliminación de Secuencia , Síndrome
10.
J Med Genet ; 46(3): 192-7, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19066168

RESUMEN

BACKGROUND: Silver-Russell syndrome (SRS) is a clinically and genetically heterogeneous condition characterised by severe intrauterine and postnatal growth retardation. Loss of DNA methylation at the telomeric imprinting control region 1 (ICR1) on 11p15 is an important cause of SRS. METHODS: We studied the methylation pattern at the H19-IGF2 locus in 201 patients with suspected SRS. In an attempt to categorise the patients into different subgroups, we developed a simple clinical scoring system with respect to readily and unambiguously assessable clinical features. In a second step, the relationship between clinical score and epigenetic status was analysed. RESULTS AND CONCLUSIONS: The scoring system emerged as a powerful tool for identifying those patients with both a definite SRS phenotype and carrying an epimutation at 11p15. 53% of the 201 patients initially enrolled fulfilled the criteria for SRS and about 40% of them exhibited an epimutation at the H19-IGF2 locus. Methylation defects were restricted to patients who fulfilled the diagnostic criteria for SRS. Patients carrying epimutations had a more severe phenotype than either the SRS patients with mUPD7 or the idiopathic SRS patients. The majority of patients with methylation abnormalities showed hypomethylation at both the H19 and IGF2 genes. However, we also identified SRS patients where hypomethylation was restricted to either the H19 or the IGF2 gene. Interestingly, we detected epimutations in siblings of normal parents, most likely reflecting germ cell mosaicism in the fathers. In one family, we identified an epimutation in an affected father and his likewise affected daughter.


Asunto(s)
Anomalías Múltiples/genética , Epigénesis Genética , Factor II del Crecimiento Similar a la Insulina/genética , Mutación , Adolescente , Adulto , Análisis de Varianza , Niño , Preescolar , Estudios de Cohortes , Anomalías Craneofaciales/genética , Metilación de ADN , Femenino , Retardo del Crecimiento Fetal/genética , Impresión Genómica , Humanos , Lactante , Masculino , Fenotipo , Embarazo , Proyectos de Investigación , Síndrome , Disomía Uniparental
11.
J Med Genet ; 46(4): 233-41, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19088120

RESUMEN

BACKGROUND: Recessive forms of osteogenesis imperfecta (OI) may be caused by mutations in LEPRE1, encoding prolyl 3-hydroxylase-1 (P3H1) or in CRTAP, encoding cartilage associated protein. These proteins constitute together with cyclophilin B (CyPB) the prolyl 3-hydroxylation complex that hydroxylates the Pro986 residue in both the type I and type II collagen alpha1-chains. METHODS: We screened LEPRE1, CRTAP and PPIB (encoding CyPB) in a European/Middle Eastern cohort of 20 lethal/severe OI patients without a type I collagen mutation. RESULTS: Four novel homozygous and compound heterozygous mutations were identified in LEPRE1 in four probands. Two probands survived the neonatal period, including one patient who is the eldest reported patient (17 7/12 years) so far with P3H1 deficiency. At birth, clinical and radiologic features were hardly distinguishable from those in patients with autosomal dominant (AD) severe/lethal OI. Follow-up data reveal that the longer lived patients develop a severe osteochondrodysplasia that overlaps with, but has some distinctive features from, AD OI. A new splice site mutation was identified in two of the four probands, affecting only one of three LEPRE1 mRNA splice forms, detected in this study. The affected splice form encodes a 736 amino acid (AA) protein with a "KDEL" endoplasmic reticulum retention signal. While western blotting and immunocytochemical analysis of fibroblast cultures revealed absence of this P3H1 protein, mass spectrometry and SDS-urea-PAGE data showed severe reduction of alpha1(I)Pro986 3-hydroxylation and overmodification of type I (pro)collagen chains in skin fibroblasts of the patients. CONCLUSION: These findings suggest that the 3-hydroxylation function of P3H1 is restricted to the 736AA splice form.


Asunto(s)
Glicoproteínas de Membrana/genética , Mutación , Osteogénesis Imperfecta/genética , Proteoglicanos/genética , Empalme Alternativo , Western Blotting , Células Cultivadas , Estudios de Cohortes , Colágeno Tipo I/metabolismo , Ciclofilinas/genética , Ciclofilinas/metabolismo , Análisis Mutacional de ADN , Electroforesis en Gel de Poliacrilamida , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/metabolismo , Fibroblastos/citología , Fibroblastos/metabolismo , Expresión Génica , Genes Recesivos , Pruebas Genéticas , Humanos , Hidroxilación , Inmunohistoquímica , Isoenzimas/genética , Isoenzimas/metabolismo , Glicoproteínas de Membrana/metabolismo , Chaperonas Moleculares , Osteogénesis Imperfecta/diagnóstico , Prolil Hidroxilasas , Proteoglicanos/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Espectrometría de Masas en Tándem
12.
J Med Genet ; 46(8): 562-8, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19508970

RESUMEN

BACKGROUND: Schneckenbecken dysplasia (SBD) is an autosomal recessive lethal skeletal dysplasia that is classified into the severe spondylodysplastic dysplasias (SSDD) group in the international nosology for skeletal dysplasias. The radiological hallmark of SBD is the snail-like configuration of the hypoplastic iliac bone. SLC35D1 (solute carrier-35D1) is a nucleotide-sugar transporter involved in proteoglycan synthesis. Recently, based on human and mouse genetic studies, we showed that loss-of-function mutations of the SLC35D1 gene (SLC35D1) cause SBD. OBJECT: To explore further the range of SLC35D1 mutations in SBD and elucidate whether SLC35D1 mutations cause other skeletal dysplasias that belong to the SSDD group. METHODS AND RESULTS: We searched for SLC35D1 mutations in five families with SBD and 15 patients with other SSDD group diseases, including achodrogenesis type 1A, spondylometaphyseal dysplasia Sedaghatian type and fibrochondrogenesis. We identified four novel mutations, c.319C>T (p.R107X), IVS4+3A>G, a 4959-bp deletion causing the removal of exon 7 (p.R178fsX15), and c.193A>C (p. T65P), in three SBD families. Exon trapping assay showed IVS4+3A>G caused skipping of exon 4 and a frameshift (p.L109fsX18). Yeast complementation assay showed the T65P mutant protein lost the transporter activity of nucleotide sugars. Therefore, all these mutations result in loss of function. No SLC35D1 mutations were identified in all patients with other SSDD group diseases. CONCLUSION: Our findings suggest that SLC35D1 loss-of-function mutations result consistently in SBD and are exclusive to SBD.


Asunto(s)
Enfermedades del Desarrollo Óseo/genética , Enfermedades Fetales/genética , Eliminación de Gen , Proteínas de Transporte de Monosacáridos/genética , Mutación , Secuencia de Bases , Clonación Molecular , Femenino , Humanos , Masculino , Datos de Secuencia Molecular , Nucleótidos/metabolismo , Reacción en Cadena de la Polimerasa , Embarazo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Alineación de Secuencia
13.
Neuromuscul Disord ; 29(8): 601-613, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-31443951

RESUMEN

We genetically evaluated 260 dystrophinopathy patients from Turkey. Karyotyping as an initial test in female patients, followed stepwise by multiplex ligation-dependent probe amplification and by targeted next-generation sequencing of DMD revealed definitive genetic diagnoses in 214 patients (82%), with gross deletions/duplications in 153 (59%), pathogenic sequence variants in 60 (23%), and X-autosome translocation in one. Seven of the gross and 27 of the sequence variants found novel. In silico prediction, co-segregation and transcript assays supported the pathogenic nature of the novel silent (p.Lys534=) and the splice site (c.4345-12C>G) alterations. From a total of 189 singleton cases, 154 (82%) had pathogenic alterations. From 138 of those who had maternal carrier testing, 68 out of 103 (66%) showed gross and 11 out of 35 (31%) showed small pathogenic variants. This suggests that the de novo occurrences in DMD appear approximately 2.1 times more frequently in meiotic unequal crossing-over than in uncorrected replication errors. Our study also disclosed three mothers as obligate gonadal mosaic carriers. Family-based investigation of dystrophinopathy patients is crucial for the ascertainment of novel or rare variants and also for counseling and follow-up care of the families.


Asunto(s)
Distrofina/genética , Asesoramiento Genético , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/fisiopatología , Adulto , Niño , Preescolar , Estudios de Cohortes , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Lactante , Masculino , Mutación , Fenotipo , Análisis de Secuencia de ADN , Turquía , Adulto Joven
14.
J Dent Res ; 97(1): 49-59, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28813618

RESUMEN

Tooth agenesis is a common craniofacial abnormality in humans and represents failure to develop 1 or more permanent teeth. Tooth agenesis is complex, and variations in about a dozen genes have been reported as contributing to the etiology. Here, we combined whole-exome sequencing, array-based genotyping, and linkage analysis to identify putative pathogenic variants in candidate disease genes for tooth agenesis in 10 multiplex Turkish families. Novel homozygous and heterozygous variants in LRP6, DKK1, LAMA3, and COL17A1 genes, as well as known variants in WNT10A, were identified as likely pathogenic in isolated tooth agenesis. Novel variants in KREMEN1 were identified as likely pathogenic in 2 families with suspected syndromic tooth agenesis. Variants in more than 1 gene were identified segregating with tooth agenesis in 2 families, suggesting oligogenic inheritance. Structural modeling of missense variants suggests deleterious effects to the encoded proteins. Functional analysis of an indel variant (c.3607+3_6del) in LRP6 suggested that the predicted resulting mRNA is subject to nonsense-mediated decay. Our results support a major role for WNT pathways genes in the etiology of tooth agenesis while revealing new candidate genes. Moreover, oligogenic cosegregation was suggestive for complex inheritance and potentially complex gene product interactions during development, contributing to improved understanding of the genetic etiology of familial tooth agenesis.


Asunto(s)
Anodoncia/genética , Femenino , Ligamiento Genético/genética , Variación Genética/genética , Humanos , Péptidos y Proteínas de Señalización Intercelular/genética , Laminina/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Masculino , Proteínas de la Membrana/genética , Mutación Missense/genética , Linaje , Reacción en Cadena en Tiempo Real de la Polimerasa , Turquía , Secuenciación del Exoma/métodos , Proteínas Wnt/genética
15.
J Med Genet ; 43(2): e5, 2006 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-16467215

RESUMEN

BACKGROUND: Desmosomes are cellular junctions important for intercellular adhesion and anchoring the intermediate filament (IF) cytoskeleton to the cell membrane. Desmoplakin (DSP) is the most abundant desmosomal protein with 2 isoforms produced by alternative splicing. METHODS: We describe a patient with a recessively inherited arrhythmogenic dilated cardiomyopathy with left and right ventricular involvement, epidermolytic palmoplantar keratoderma, and woolly hair. The patient showed a severe heart phenotype with an early onset and rapid progression to heart failure at 4 years of age. RESULTS: A homozygous nonsense mutation, R1267X, was found in exon 23 of the desmoplakin gene, which results in an isoform specific truncation of the larger DSPI isoform. The loss of most of the DSPI specific rod domain and C-terminal area was confirmed by Western blotting and immunofluorescence. We further showed that the truncated DSPI transcript is unstable, leading to a loss of DSPI. DSPI is reported to be an obligate constituent of desmosomes and the only isoform present in cardiac tissue. To address this, we reviewed the expression of DSP isoforms in the heart. Our data suggest that DSPI is the major cardiac isoform but we also show that specific compartments of the heart have detectable DSPII expression. CONCLUSIONS: This is the first description of a phenotype caused by a mutation affecting only one DSP isoform. Our findings emphasise the importance of desmoplakin and desmosomes in epidermal and cardiac function and additionally highlight the possibility that the different isoforms of desmoplakin may have distinct functional properties within the desmosome.


Asunto(s)
Cardiomiopatías/genética , Cardiomiopatías/fisiopatología , Desmoplaquinas/deficiencia , Desmoplaquinas/genética , Edad de Inicio , Cardiomiopatías/epidemiología , Preescolar , Análisis Mutacional de ADN , Técnica del Anticuerpo Fluorescente , Regulación de la Expresión Génica , Haplotipos/genética , Humanos , Masculino , Miocardio/metabolismo , Linaje , Isoformas de Proteínas/deficiencia , Isoformas de Proteínas/genética , Piel/metabolismo , Síndrome , gamma Catenina/genética
17.
J Neurol Sci ; 246(1-2): 123-30, 2006 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-16730748

RESUMEN

Mutations in Notch3 gene are responsible for the cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). It is a late onset neurological disorder recognized by recurrent strokes and dementia. We describe here the clinical and molecular findings of three unrelated Turkish families with CADASIL syndrome. Two of the families were identified to have the same mutation, p.R110C (c.C328T), located in exon 3 of the Notch3 gene. Interestingly, the phenotypic expression of the disease in these two families was markedly different in severity and age of onset implicating additional genetic and/or non-genetic modulating factors involved in the pathogenesis. In addition, we identified the novel p.C201R (c.T601C) mutation in exon 4 of the Notch3 gene in a proband of the third family with two consecutive stroke-like episodes and typical MRI findings. Mutations described here cause an odd number of cysteines in the N-terminal of the EGF domain of Notch3 protein, which seems to have an important functional effect in the pathophysiology of CADASIL. The phenotypic variability in families carrying the same molecular defect as presented here makes the prediction of prognosis inconceivable. Although DNA analysis is effective and valuable in diagnosing approximately 90% of the CADASIL patients, lack of genotype-phenotype correlation and prognostic parameters makes the presymptomatic genetic counseling very difficult.


Asunto(s)
CADASIL/genética , CADASIL/fisiopatología , Mutación/genética , Mutación/fisiología , Receptores Notch/genética , Adulto , Edad de Inicio , Anciano , Encéfalo/patología , Cisteína/genética , Cisteína/fisiología , ADN/genética , Exones/genética , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Linaje , Fenotipo , Receptor Notch3 , Turquía
18.
J Med Genet ; 42(5): 408-15, 2005 May.
Artículo en Inglés | MEDLINE | ID: mdl-15863670

RESUMEN

BACKGROUND: Congenital fibrosis of the extraocular muscles (CFEOM) is a heterogeneous group of disorders that may be associated with other anomalies. The association of a CFEOM syndrome with ulnar hand abnormalities (CFEOM/U) has not been reported to date. OBJECTIVE: To describe a new autosomal recessive syndrome of CFEOM and ulnar hand abnormalities, and localise the disease causing gene. METHODS: Clinical evaluation of the affected members and positional mapping. RESULTS: Six affected patients with CFEOM/U (aged 2 to 29 years) from a large consanguineous Turkish family were studied. Ophthalmological involvement was characterised by non-progressive restrictive ophthalmoplegia with blepharoptosis of the right eye. The postaxial oligodactyly/oligosyndactyly of the hands was more severe on the right side. A genome-wide scan established linkage of this new autosomal recessive syndrome to a locus on chromosome 21qter. The multipoint LOD score was 4.53 at microsatellite marker D21S1259, and fine mapping defined a approximately 1.5 Mb critical region between microsatellite marker D21S1897 and the telomere of the long arm. CONCLUSIONS: CFEOM/U maps to a 1.5 Mb region at chromosome 21qter. Future identification of the disease causing gene may provide insights into the development of the extraocular muscles and brain stem alpha motor neurones, as well as anteroposterior limb development.


Asunto(s)
Cromosomas Humanos Par 21/genética , Deformidades Congénitas de la Mano/genética , Trastornos de la Motilidad Ocular/genética , Músculos Oculomotores/patología , Cúbito/anomalías , Adulto , Preescolar , Mapeo Cromosómico , Femenino , Fibrosis , Ligamiento Genético , Deformidades Congénitas de la Mano/patología , Humanos , Masculino , Trastornos de la Motilidad Ocular/patología , Linaje , Síndrome , Turquía/etnología
19.
J Med Genet ; 37(5): 371-5, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10807697

RESUMEN

We report a unique glycine substitution in type I collagen and highlight the clinical and biochemical consequences. The proband is a 9 year old Turkish boy with severely deforming osteogenesis imperfecta (OI). Biochemical analysis of (pro) collagen type I from a skin fibroblast culture showed both normal and overmodified alpha chains. Molecular analysis showed a G>T transversion in the COL1A2 gene, resulting in the substitution of glycine by tryptophan at position 277 of the alpha2(I) collagen chain. Glycine substitutions in type I collagen are the most frequent cause of the severe and lethal forms of OI. The phenotypic severity varies according to the nature and localisation of the mutation. Substitutions of glycine by tryptophan, which is the most voluminous amino acid, have not yet been identified in type I collagen or any other fibrillar collagen. The severe, though non-lethal OI phenotype associated with this mutation may appear surprising in view of the huge size of the tryptophan residue. The fact that the mutation resides within a so called "non-lethal" region of the alpha2(I) collagen chain supports a regional model in phenotypic severity for alpha2(I) collagen mutations, in which the phenotype is determined primarily by the nature of the collagen domain rather than the type of glycine substitution involved.


Asunto(s)
Sustitución de Aminoácidos , Colágeno/genética , Glicina/genética , Osteogénesis Imperfecta/genética , Triptófano/genética , Adulto , Niño , Colágeno/metabolismo , Femenino , Humanos , Masculino , Osteogénesis Imperfecta/metabolismo , Osteogénesis Imperfecta/patología , Mutación Puntual , Reacción en Cadena de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa
20.
Hum Mutat ; 15(6): 578, 2000 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10862090

RESUMEN

Homozygosity for a frameshift mutation at codon 1213 of FANCA gene was identified in a Turkish patient. Immunoprecipitation-western blot analysis showed the complete absence of the FANCA protein band. This novel mutation, a deletion of T at position 3639 in exon 37 (3639delT), is responsible for the disease and causes premature termination of translation 32 aa downstream. The deletion is (i) the T residue of 2 overlapping TGAGGC and CCTG hot spot motifs, (ii) flanked by several direct repeats, (iii) surrounded by the highly GC rich region that have frequently been identified at the site of human DNA deletions. The patient is the third living child of a first degree cousin marriage. The major abnormalities of the patient at the age of 6 months were growth retardation, microcephaly, hypoplastic right thumb, distal displacements of both thumbs and pelvic displacement of left kidney. Hematological presentation of the disease started before the age of 4 years.


Asunto(s)
Proteínas de Ciclo Celular , Proteínas de Unión al ADN , Anemia de Fanconi/genética , Mutación del Sistema de Lectura/genética , Proteínas Nucleares , Proteínas/genética , Niño , Preescolar , Codón/genética , Anemia de Fanconi/patología , Proteínas del Grupo de Complementación de la Anemia de Fanconi , Femenino , Humanos , Lactante
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