RESUMO
The genetic relevance of small supernumerary marker chromosomes (sSMCs) depends on their content of euchromatin. In case of mosaicism, the phenotype of the carrier furthermore is influenced by the distribution of the marker in the body. In the majority of reported cases no correlation of the degree of mosaicism in the tissue(s) analyzed and the phenotype could be detected. In particular, non-acrocentric derived sSMCs show a strong tendency to appear in mosaic state irrespective of the clinical picture. We present a patient with cognitive disability and mild craniofacial dysmorphisms with mosaicism of three different autosomal marker chromosomes. The extra chromosomes were analyzed by a combination of SNP array and a variety of fluorescence in situ hybridization (FISH) probes. All three markers were identified as ring chromosomes containing different amounts of euchromatic material derived from chromosome 1 (1p12 â q21), 12 (12p13.1 â q13.11) and 18 (18p11.21 â q11.2). The size and the frequency of the sSMCs were strikingly different, besides, we observed an unequal combination of the three derivates.
Assuntos
Aberrações Cromossômicas , Transtornos Cromossômicos/diagnóstico , Transtornos Cromossômicos/genética , Cromossomos Humanos Par 12 , Cromossomos Humanos Par 18 , Cromossomos Humanos Par 1 , Eucromatina , Pré-Escolar , Fácies , Feminino , Marcadores Genéticos , Humanos , Hibridização in Situ Fluorescente , Cariotipagem , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Marinesco-Sjögren syndrome is a rare autosomal recessive multisystem disorder featuring cerebellar ataxia, early-onset cataracts, chronic myopathy, variable intellectual disability and delayed motor development. More recently, mutations in the SIL1 gene, which encodes an endoplasmic reticulum resident co-chaperone, were identified as the main cause of Marinesco-Sjögren syndrome. Here we describe the results of SIL1 mutation analysis in 62 patients presenting with early-onset ataxia, cataracts and myopathy or combinations of at least two of these. We obtained a mutation detection rate of 60% (15/25) among patients with the characteristic Marinesco-Sjögren syndrome triad (ataxia, cataracts, myopathy) whereas the detection rate in the group of patients with more variable phenotypic presentation was below 3% (1/37). We report 16 unrelated families with a total of 19 different SIL1 mutations. Among these mutations are 15 previously unreported changes, including single- and multi-exon deletions. Based on data from our screening cohort and data compiled from the literature we found that SIL1 mutations are invariably associated with the combination of a cerebellar syndrome and chronic myopathy. Cataracts were observed in all patients beyond the age of 7 years, but might be missing in infants. Six patients with SIL1 mutations had no intellectual disability, extending the known wide range of cognitive capabilities in Marinesco-Sjögren syndrome to include normal intelligence. Modestly constant features were somatic growth retardation, skeletal abnormalities and pyramidal tract signs. Examination of mutant SIL1 expression in cultured patient lymphoblasts suggested that SIL1 mutations result in severely reduced SIL1 protein levels irrespective of the type and position of mutations. Our data broaden the SIL1 mutation spectrum and confirm that SIL1 is the major Marinesco-Sjögren syndrome gene. SIL1 patients usually present with the characteristic triad but cataracts might be missing in young children. As cognitive impairment is not obligatory, patients without intellectual disability but a Marinesco-Sjögren syndrome-compatible phenotype should receive SIL1 mutation analysis. Despite allelic heterogeneity and many families with private mutations, the phenotype related to SIL1 mutations is relatively homogenous. Based on SIL1 expression studies we speculate that this may arise from a uniform effect of different mutations on protein expression.
Assuntos
Fatores de Troca do Nucleotídeo Guanina/genética , Mutação/genética , Degenerações Espinocerebelares/genética , Adolescente , Linfócitos B , Encéfalo/patologia , Encéfalo/ultraestrutura , Células Cultivadas , Análise Mutacional de DNA , Saúde da Família , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Músculo Esquelético/patologia , Músculo Esquelético/ultraestrutura , Estudos Retrospectivos , Degenerações Espinocerebelares/patologia , Degenerações Espinocerebelares/fisiopatologiaRESUMO
Xanthinuria Type I is caused by mutations in the xanthine dehydrogenase gene (XDH). We report on a patient suffering from xanthinuria. Genomic DNA was screened for point mutations and imbalances in the XDH gene by sequencing and microarray typing. We could identify homozygosity of a multiexon deletion in the XDH gene; large genomic imbalances have not yet been reported in this disease. As our case and other studies on genetic alterations in kidney diseases show, large deletions (and duplications) significantly contribute to the etiology of these entities, specific assays to discover these imbalances should therefore be included in genetic testing approaches.
Assuntos
Sequência de Bases , DNA/genética , Erros Inatos do Metabolismo/genética , Mutação Puntual , Deleção de Sequência , Xantina Desidrogenase/genética , Xantina/urina , Adolescente , Éxons , Humanos , Masculino , Erros Inatos do Metabolismo/urina , Xantina Desidrogenase/deficiência , Xantina Desidrogenase/urinaRESUMO
Among the clusters of imprinted genes in humans, one of the most relevant regions involved in human growth is localised in 11p15. Opposite epigenetic and genomic disturbances in this chromosomal region contribute to two distinct imprinting disorders associated with disturbed growth, Silver-Russell and Beckwith-Wiedemann syndromes. Due to the complexity of the 11p15 imprinting regions and their interactions, the interpretation of the copy number variations in that region is complicated. The clinical outcome in case of microduplications or microdeletions is therefore influenced by the size, the breakpoint positions and the parental inheritance of the imbalance as well as by the imprinting status of the affected genes. Based on their own new cases and those from the literature, the authors give an overview on the genotype-phenotype correlation in chromosomal rearrangements in 11p15 as the basis for a directed genetic counselling. The detailed characterisation of patients and families helps to further delineate risk figures for syndromes associated with 11p15 disturbances. Furthermore, these cases provide us with profound insights in the complex regulation of the (imprinted) factors localised in 11p15.
Assuntos
Cromossomos Humanos Par 11/genética , Variações do Número de Cópias de DNA/genética , Impressão Genômica/genética , Adulto , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Linhagem , Adulto JovemRESUMO
OBJECTIVE: To determine the contribution of submicroscopic chromosomal imbalances to the etiology of Silver-Russell syndrome (SRS) and SRS-like phenotypes. STUDY DESIGN: We performed molecular karyotyping in 41 patients with SRS or SRS-like features without known chromosome 7 and 11 defects using the Affymetrix SNP Array 6.0 system (Affymetrix, High Wycombe, United Kingdom). RESULTS: In 8 patients, pathogenic copy number variations with sizes ranging from 672 kb to 9.158 Mb were identified. The deletions in 1q21, 15q26, 17p13, and 22q11 were associated with known microdeletion syndromes with overlapping features with SRS. The duplications in 22q13 and Xq25q27 represent unique novel copy number variations but have an obvious influence on the phenotype. In 5 additional patients, the pathogenetic relevance of the detected variants remained unclear. CONCLUSION: Pathogenic submicroscopic imbalances were detectable in a significant proportion of patients with short stature and features reminiscent of SRS. Therefore, molecular karyotyping should be implemented in routine diagnostics for growth-retarded patients with even slight dysmorphisms suggestive for SRS.
Assuntos
Transtornos do Crescimento/diagnóstico , Cariotipagem/métodos , Síndrome de Silver-Russell/diagnóstico , Síndrome de Silver-Russell/genética , Criança , Pré-Escolar , Aberrações Cromossômicas , Deleção Cromossômica , Cromossomos Humanos Par 11/genética , Cromossomos Humanos Par 7/genética , Feminino , Marcadores Genéticos/genética , Transtornos do Crescimento/genética , Humanos , Lactente , Masculino , Mutação , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Aberrant methylation at different imprinted loci has been reported for several congenital imprinting disorders, that is, Silver-Russell syndrome (SRS), but the coincidental occurrence of aberrant methylation and uniparental disomy (UPD) has not yet been described. We report on a patient initially diagnosed with SRS carrying a segmental maternal UPD of chromosome 7 [upd(7q)mat]. By further screening the patient's DNA for methylation defects on other chromosomes we identified a hypomethylation of the paternally methylated DLK1/GTL2 locus in 14q32, an epigenotype typically associated with the upd(14)mat phenotype. Detailed clinical analysis confirmed the molecular finding in the patient indicating that the 14q32 epimutation was clinically preponderant. The parallel occurrence of upd(7q)mat and a DLK1/GTL2 hypomethylation in the same patient is a unique finding. Indeed, both disturbances might have occurred coincidentally, but it can also be hypothesized that the upd(7q)mat as the initial genomic mutation represents a trans-acting mutation causing an aberrant methylation in 14q32.
Assuntos
Metilação de DNA/genética , Síndrome de Silver-Russell/genética , Síndrome de Silver-Russell/patologia , Dissomia Uniparental/diagnóstico , Dissomia Uniparental/genética , Proteínas de Ligação ao Cálcio , Pré-Escolar , Cromossomos Humanos Par 14 , Cromossomos Humanos Par 7 , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas/genética , Proteínas/metabolismo , RNA Longo não Codificante , Síndrome de Silver-Russell/diagnósticoRESUMO
Chromosomal duplications and deletions in 7p12.2 have been described in patients with growth disturbance phenotypes, that is, Silver-Russell and Beckwith-Wiedemann syndrome (SRS, BWS). The region harbors the imprinted GRB10/Grb10 gene which has been postulated to belong to a major fetal growth pathway. Based on its genomic localization, its physiological function and its imprinting status, GRB10/Grb10 was considered as a candidate for growth disturbance disorders. However, based on case reports with imbalances of the GRB10 locus it has been suggested that the altered GRB10 copy number should be responsible for the aberrant growth phenotype rather than an altered imprinting status of the gene. We now report on a patient with an increased height and weight in his first years of life carrying a de-novo duplication (5.1 Mb) of paternal 7p12.2 material. The increased growth in this patient again contradicts the hypothesis that a gain of GRB10 copies leads to growth restriction. Indeed, it is necessary to compare the regions of imbalances in 7p12 and the affected genes in the different patients as other genes than GRB10 in 7p12 might cause these aberrant growth phenotypes.
Assuntos
Cromossomos Humanos Par 7 , Proteína Adaptadora GRB10/genética , Impressão Genômica , Transtornos do Crescimento/genética , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/genética , Hibridização Genômica Comparativa , Fácies , Duplicação Gênica , Transtornos do Crescimento/diagnóstico , Humanos , Lactente , Masculino , FenótipoRESUMO
Several duplications of chromosome 21q helped to narrow down the Down syndrome (DS) critical region (DSCR) to chromosomal band 21q22 with an approximate length of 5.4 Mb. Recently, it has been suggested that the facial gestalt of DS has been linked to the distal part of the DSCR whereas the proximal region harboring DSCR1/RCAN and DSCAM should be associated with the cardiac abnormalities. Here, we report on a patient with Silver-Russell syndrome (SRS) and a paternally inherited 0.46 Mb duplication in 21q22 affecting the KCNE1 and DSCR1/RCAN genes. The identification of an involvement of KCNE1 was interesting because it encodes the beta-subunit of the KvLQT1 channel as the slow component of the cardiac delayed rectifier K(+) current. Since duplication of the KCNQ1 gene encoding the alpha-subunit of the same channel was reported recently in another SRS patient, we screened both genes for mutations in a cohort of SRS patients without detecting pathologic variants. We presume that the duplication of the two functionally linked genes in different patients with the same disorder is a coincidental finding. However, the lack of DS typical clinical features in our case allows us to further narrow down the DSCR in 21q22. We conclude that DSCR1/RCAN is not sufficient for generating phenotypic features associated with DS but our observation does not contradict a possible role for DSCR1/RCAN in mediating DYRK1A-based effects.
Assuntos
Cromossomos Humanos Par 21 , Síndrome de Down/genética , Duplicação Gênica , Mutação , Síndrome de Silver-Russell/genética , Adulto , Bandeamento Cromossômico , Estudos de Coortes , Proteínas de Ligação a DNA , Genótipo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Canal de Potássio KCNQ1/genética , Masculino , Proteínas Musculares/genética , Polimorfismo de Nucleotídeo Único , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genéticaRESUMO
The role of 11p15 disturbances in the aetiology of Silver-Russell syndrome (SRS) is well established: in addition to hypomethylation of the H19/IGF2 differentially methylated regions, five patients with a duplication of maternal 11p15 material have been described. We report on a boy with SRS carrying a maternally inherited duplication of chromosome 11p15. The patient showed the typical clinical picture of SRS including severe intrauterine and postnatal growth restriction, relative macrocephaly, a prominent forehead, a triangular face, down-turned corners of the mouth and fifth digit clinodactyly. Body asymmetry was not observed. By molecular genetic analyses, MLPA and microsatellite typing detected a duplication of chromosome 11p15 and cytogenetic analysis showed an unbalanced translocation t(11;15)(p15.5:p12). The size of the duplicated region is approximately 8.8 Mb as determined by SNP-array analysis. The healthy mother carried a balanced reciprocal chromosome translocation t(11;15). Thus, there is an increased risk for further children with SRS due to 11p15 duplication. Additionally, the family is at risk for offspring with an 11p15 deletion and Beckwith-Wiedemann syndrome whereby the phenotype will be influenced by haploinsufficiency of additional genes at 11p15 due to the deletion. The balanced aberrant karyotype was identified in several other family members, but interestingly there was no history of recurrent miscarriages, intrauterine fetal death, or multiple congenital anomaly syndromes in the family.
Assuntos
Cromossomos Humanos Par 11/genética , Síndrome de Silver-Russell/genética , Translocação Genética , Adulto , Pré-Escolar , Feminino , Humanos , Masculino , Mães , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Silver-Russell syndrome (SRS) is a genetically and clinically heterogeneous disease which is mainly characterized by pre- and postnatal growth restriction. The typical SRS phenotype furthermore includes a relative macrocephaly, a triangular shaped face, body asymmetry, clinodactyly of the fifth finger and other less constant features. In about ~50% of patients (epi)genetic alterations involving chromosomes 7 and 11 can be detected. The major finding (~44%) is a hypomethylation of the imprinting control region 1 (ICR1) in 11p15.5 affecting the expression of H19 and IGF2. 4-10% of the patients carry a maternal UPD of chromosome 7 (UPD(7)mat). In a few cases chromosomal rearrangements have been reported. The diagnostic workup should therefore include 11p15 testing, UPD(7)mat analysis and molecular karyotyping. The recurrence risk is generally low in SRS but it can strongly increase in case of familial epimutations or chromosomal rearrangements. Interestingly, in ~7% of 11p15 hypomethylation carriers, hypomethylation of additional imprinted loci can be detected. Clinically, patients with hypomethylation at multiple loci do not differ from those with isolated ICR1 hypomethylation whereas the UPD(7)mat patients generally show a milder phenotype. Nevertheless, an unambiguous (epi)genotype-phenotype correlation can not be delineated. Furthermore, the pathophysiological mechanisms resulting in the SRS phenotype still remain unknown despite the recent progress in deciphering molecular defects in the disease.
Assuntos
Cromossomos Humanos Par 11 , Cromossomos Humanos Par 7 , Epigênese Genética/genética , Aconselhamento Genético , Síndrome de Silver-Russell/genética , Criança , HumanosRESUMO
Silver-Russell syndrome (SRS) is a heterogeneous disease associated with intrauterine and postnatal growth retardation (IUGR/PNGR), asymmetry and craniofacial dysmorphisms. In 7-10% of patients with SRS, maternal uniparental disomy of chromosome 7 can be detected; more than 38% carry hypomethylation of the imprinting region 1 in 11p15. These chromosomes harbor the imprinted genes IGF2, H19, LIT1 and MEST. In mice, interaction of these genes with the prenatally rexpressed Plagl1/Zac1 has been reported. The aim of this study was to identify mutations in the maternally imprinted LOT1(ZAC1/PLAGL1) gene in 6q24 in patients with SRS. We screened 30 patients with SRS and 14 patients with isolated IUGR/PNGR by SSCP and/or direct sequencing. Mutation analysis revealed nine genomic variants. Seven were novel but classified as apathogenic. Interestingly, two of these variants, g.10212T/A and g.10214C/A, showed strict association. However, our results do not indicate a relevant role of mutations in LOT1(ZAC1/PLAGL1) in the etiology of SRS.
Assuntos
Proteínas de Ciclo Celular/genética , Anormalidades Craniofaciais/genética , Retardo do Crescimento Fetal/genética , Fatores de Transcrição/genética , Proteínas Supressoras de Tumor/genética , Animais , Sequência de Bases , Cromossomos Humanos Par 11 , Cromossomos Humanos Par 7 , Metilação de DNA , Análise Mutacional de DNA , Impressão Genômica , Humanos , Recém-Nascido , Camundongos , Dados de Sequência Molecular , Mutação , Polimorfismo de Nucleotídeo Único , Polimorfismo Conformacional de Fita Simples , Síndrome , Dissomia UniparentalAssuntos
Anormalidades Múltiplas/genética , Impressão Genômica , Adolescente , Criança , Pré-Escolar , Mapeamento Cromossômico , Metilação de DNA , Epigênese Genética , Feminino , Estudos de Associação Genética , Heterozigoto , Humanos , Lactente , Masculino , Fenótipo , Síndrome , Dissomia Uniparental/genéticaRESUMO
Uniparental disomy (UPD) of single chromosomes is a well-known molecular aberration in a group of congenital diseases commonly known as imprinting disorders (IDs). Whereas maternal and/or paternal UPD of chromosomes 6, 7, 11, 14 and 15 are associated with specific IDs (Transient neonatal diabetes mellitus, Silver-Russell syndrome, Beckwith-Wiedemann syndrome (BWS), upd(14)-syndromes, Prader-Willi syndrome, Angelman Syndrome), the other autosomes are not. UPD of the whole genome is not consistent with life, in case of non-mosaic genome-wide paternal UPD (patUPD) it leads to hydatidiform mole. In contrast, mosaic genome-wide patUPD might be compatible with life. Here we present a 19-year-old woman with BWS features and initially diagnosed to be carrier of a mosaic patUPD of chromosome 11p15. However, the patient presented further clinical findings not typically associated with BWS, including nesidioblastosis, fibroadenoma, hamartoma of the liver, hypoglycaemia and ovarian steroid cell tumour. Additional molecular investigations revealed a mosaic genome-wide patUPD. So far, only nine cases with mosaic genome-wide patUPD and similar clinical findings have been reported, but these patients were nearly almost diagnosed in early childhood. Summarising the data from the literature and those from our patient, it can be concluded that the mosaic genome-wide patUPD (also known as androgenic/biparental mosaicism) might explain unusual BWS phenotypes. Thus, these findings emphasise the need for multilocus testing in IDs to efficiently detect cases with disturbances affecting more than one chromosome.
Assuntos
Síndrome de Beckwith-Wiedemann/genética , Metilação de DNA/genética , Mosaicismo , Dissomia Uniparental/genética , Síndrome de Beckwith-Wiedemann/patologia , Pré-Escolar , Aberrações Cromossômicas , Feminino , Impressão Genômica , Humanos , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Fenótipo , Síndrome de Prader-Willi/genética , Gravidez , Dissomia Uniparental/patologiaRESUMO
The insulin-like growth factor 1 receptor (IGF1R) is a key factor in intrauterine and postnatal growth by mediating the biological function of IGF-I. Mutations of IGF1R gene are usually associated with growth retardation, but the clinical picture of IGF1R mutation carriers is heterogeneous. Indeed, these patients show clinical signs compatible with Silver-Russell syndrome (SRS), and some IGF1R mutation carriers have been identified in SRS cohorts. We therefore investigated deoxyribonucleic acid samples of 19 growth-retarded patients with SRS features. Apart from 8 non-pathogenic variants, we detected heterozygosity for the unknown duplication, c.1056_1057dup, leading to a premature termination in one patient and his growth retarded sister. Due to its nature, we assumed that this variant is probably pathogenic. However, the patient and his sister exhibited spontaneous catch-up growth in later life. We therefore hypothesize that the c.1056_1057dup does not result in a significant disruption to the GH-IGFI axis. Thus, this IGF1R mutation without obvious clinical consequence might challenge the actual concept of IGF1R haploinsufficiency as a general cause for disturbed growth in IGF1R mutation carriers. In the future, mutation analysis of IGF1R should be considered in growth-retarded patients with microcephaly and minor SRS features, but not in probands with the characteristic SRS phenotype including macrocephaly.
RESUMO
Silver-Russell syndrome (SRS) is a congenital imprinting disorder characterized by intrauterine and postnatal growth restriction and further characteristic features. SRS is genetically heterogenous: 7-10% of patients carry a maternal uniparental disomy of chromosome 7; >38% show a hypomethylation in imprinting control region 1 in 11p15; and a further class of mutations are copy number variations affecting different chromosomes, but mainly 11p15 and 7. The diagnostic work-up should thus aim to detect these three molecular subtypes. Numerous techniques are currently applied in genetic SRS testing, but none of them covers all known (epi)mutations, and they should therefore be used synergistically. However, future next-generation sequencing approaches will allow a comprehensive analysis of all types of alterations in SRS.
Assuntos
Aberrações Cromossômicas , Cromossomos Humanos Par 11/genética , Cromossomos Humanos Par 7/genética , Metilação de DNA , Síndrome de Silver-Russell/diagnóstico , Síndrome de Silver-Russell/genética , Testes Genéticos , Genótipo , Transtornos do Crescimento/genética , Humanos , Técnicas de Diagnóstico Molecular , Fenótipo , Dissomia UniparentalRESUMO
The significant role of the SLC3A1 gene in the aetiology of cystinuria is meanwhile well established and more than 130 point mutations have been reported. With the reports on genomic deletions including at least both SLC3A1 and the neighboured PREPL gene the spectrum of cystinuria mutations and of clinical symptoms could recently be enlarged: patients homozygous for these deletions suffer from a general neonatal hypotonia and growth retardation in addition to cystinuria. The hypotonia in these hypotonia-cystinuria (HCS) patients has been attributed to the total loss of the PREPL protein. Here we report on the clinical course and molecular findings in a HCS patient compound heterozygote for a new deletion in 2p21 and a previously reported deletion, both identified by molecular karyotyping. The diagnostic workup in this patient illustrates the need for a careful clinical examination in context with powerful molecular genetic tools in patients with unusual phenotypes. The identification of unique genomic alterations and their interpretation serves as a prerequisite for the individual counselling of patients and their families. In diagnostic strategies to identify the molecular basis of both cystinuria and hypotonia 2p21 deletions should be considered as the molecular basis of the phenotype.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 2/genética , Anormalidades Craniofaciais/genética , Cistinúria/genética , Deficiência Intelectual/genética , Doenças Mitocondriais/genética , Hipotonia Muscular/genética , Sistemas de Transporte de Aminoácidos Básicos/genética , Sistemas de Transporte de Aminoácidos Neutros/genética , Cromossomos Humanos Par 21/genética , Anormalidades Craniofaciais/diagnóstico , Cistinúria/diagnóstico , Heterozigoto , Humanos , Lactente , Deficiência Intelectual/diagnóstico , Cariotipagem , Masculino , Doenças Mitocondriais/diagnóstico , Hipotonia Muscular/diagnósticoRESUMO
A number of diseases have been found to be linked to aberrant methylation of specific genes. However, most of the routine diagnostic techniques to detect epigenetic disturbances are restricted to single loci. Additionally, a precise quantification of the methylation status is often hampered. A considerable fraction of patients with Silver-Russell syndrome, Beckwith-Wiedemann syndrome and transient neonatal diabetes mellitus exhibit loss of methylation at further imprinted loci in addition to the disease specific ones (multilocus methylation defects, MLMD). As the currently available tests are mainly focused on single imprinted loci on different chromosomes and thereby make the detection of multilocus methylation defects time-consuming and expensive, we established methylation-specific single nucleotide primer extension (MS-SNuPE) assays for a simultaneous quantification of methylation at multiple methylated loci. We chose loci generally affected in patients with MLMD. The method was validated by screening 66 individuals with known (epi)genetic disturbances. In comparison to other methylation-specific techniques, multilocus methylation-specific single nucleotide primer extension allows the quantitative analysis of numerous CpG islands of different loci in one assay and is, therefore, suitable for the simultaneous diagnostic testing for different congenital imprinting disorders in parallel, as well as for MLMD.
Assuntos
Metilação de DNA , Doenças Genéticas Inatas/diagnóstico , Loci Gênicos , Impressão Genômica , Tipagem de Sequências Multilocus/métodos , Nucleotídeos/metabolismo , Síndrome de Beckwith-Wiedemann/diagnóstico , Síndrome de Beckwith-Wiedemann/genética , Estudos de Casos e Controles , Cromossomos Humanos/genética , Ilhas de CpG , Primers do DNA/genética , Epigênese Genética , Doenças Genéticas Inatas/genética , Genoma Humano , Humanos , Mutação , Nucleotídeos/genética , Reprodutibilidade dos Testes , Síndrome de Silver-Russell/diagnóstico , Síndrome de Silver-Russell/genética , Dissomia Uniparental/diagnóstico , Dissomia Uniparental/genéticaRESUMO
In 2006, we reported the first case with a pure duplication of proximal 3q. In these rare aberrations, detailed clinical and developmental investigations at different ages are required to provide sufficient phenotypic documentation. Clinical and psychological differences were therefore regularly documented in our case. Supplemental genetic investigations comprised conventional karyotyping, fluorescence in-situ hybridization, single nucleotide polymorphism array analysis, and microsatellite typing. Thus, the exact position and extension of the duplication (3q13.11q23), the size (35.6 Mb), and the paternal origin could be determined. The development of our patient was followed up in detail over a period of 7.5 yr and thus enabled specific characterization of the phenotype of the patient.
RESUMO
Here we describe a patient with a new malformation syndrome which shows similarities with Yunis-Varon syndrome (YVS). Prenatal presentation included polyhydramnios, increased nuchal translucency, and bilateral hydrothoraces requiring pigtail insertion. Postnatal presentation revealed primary pulmonary hypertension (PPH), persistent hydrothoraces, one atrial and two ventricular septal defects, hypoplasia of the corpus callosum and cerebellar vermis, dilated interhemispheric ventricles, severe developmental delay with general muscular hypotonia, retinal anomalies, sparse scalp hair, sparse eyebrows and eyelashes, hypo- and aplastic nails, low-set dysplastic ears, loose nuchal skin, hypo- and aplastic distal phalanges of the toes as well as postnatal failure to thrive. High resolution molecular karyotyping in the patient did not reveal any causative chromosomal aberration. Since one patient with YVS and PPH has been previously reported, we assume a similar pathogenic pathway. However, molecular confirmation of the clinical diagnosis is not yet possible. It remains uncertain if the presented syndrome can be classified as YVS with PPH or if it constitutes a new YVS like entity.
Assuntos
Displasia Cleidocraniana/diagnóstico , Displasia Cleidocraniana/patologia , Displasia Ectodérmica/diagnóstico , Displasia Ectodérmica/patologia , Hipertensão Pulmonar/patologia , Deformidades Congênitas dos Membros/diagnóstico , Deformidades Congênitas dos Membros/patologia , Micrognatismo/diagnóstico , Micrognatismo/patologia , Doenças do Sistema Nervoso Central/complicações , Doenças do Sistema Nervoso Central/diagnóstico , Doenças do Sistema Nervoso Central/patologia , Displasia Cleidocraniana/complicações , Ecoencefalografia , Displasia Ectodérmica/complicações , Feminino , Idade Gestacional , Cardiopatias Congênitas/complicações , Cardiopatias Congênitas/diagnóstico , Cardiopatias Congênitas/patologia , Humanos , Hipertensão Pulmonar/complicações , Hipertensão Pulmonar/diagnóstico , Recém-Nascido , Cariótipo , Deformidades Congênitas dos Membros/complicações , Micrognatismo/complicações , Dedos do Pé/anormalidades , Dedos do Pé/diagnóstico por imagem , Dedos do Pé/patologiaRESUMO
Silver-Russell syndrome (SRS) is a congenital imprinting disorder mainly characterized by growth restriction, a triangular shaped face, a relative macrocephaly, and asymmetry of the body and the limbs. In 7%-10% of the patients a maternal uniparental disomy of chromosome 7 (upd(7)mat) can be observed; a hypomethylation of the imprinting control region 1 (ICR1) in 11p15 is present in >38% of patients. Methylation-specific multiplex ligation-dependent probe amplification is a well-established method for the detection of (epi)mutations in 11p15. In routine diagnostics, DNA samples derived from leukocytes are used for this testing approach. We now analyzed buccal smear DNA taken from both cheek sides of 8 carriers of an ICR1 hypomethylation and 25 SRS patients without 11p15 epimutaton or upd(7)mat to check whether (i) the epimutation can be detected in other tissues and (ii) the detection rate can be increased. Indeed, the ICR1 hypomethylation diagnosed in blood cells could be confirmed in the buccal swab DNA of all 11p15 epimutation carriers, but we could not discover any further carriers among the patients without 11p15 epimutation and upd(7)mat in lymphocytes. Thus, the overall detection rate for the 11p15 epimutation could not be increased by including further tissues originating from different germ layers. We rather assume that other-so far unknown-(genetic) factors are contributing to the etiology of SRS that escape the current diagnostic procedures.