RESUMEN
MED12 is a member of the large Mediator complex that controls cell growth, development, and differentiation. Mutations in MED12 disrupt neuronal gene expression and lead to at least three distinct X-linked intellectual disability syndromes (FG, Lujan-Fryns, and Ohdo). Here, we describe six families with missense variants in MED12 (p.(Arg815Gln), p.(Val954Gly), p.(Glu1091Lys), p.(Arg1295Cys), p.(Pro1371Ser), and p.(Arg1148His), the latter being first reported in affected females) associated with a continuum of symptoms rather than distinct syndromes. The variants expanded the genetic architecture and phenotypic spectrum of MED12-related disorders. New clinical symptoms included brachycephaly, anteverted nares, bulbous nasal tip, prognathism, deep set eyes, and single palmar crease. We showed that MED12 variants, initially implicated in X-linked recessive disorders in males, may predict a potential risk for phenotypic expression in females, with no correlation of the X chromosome inactivation pattern in blood cells. Molecular modeling (Yasara Structure) performed to model the functional effects of the variants strongly supported the pathogenic character of the variants examined. We showed that molecular modeling is a useful method for in silico testing of the potential functional effects of MED12 variants and thus can be a valuable addition to the interpretation of the clinical and genetic findings.
Asunto(s)
Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Variación Genética , Complejo Mediador/genética , Complejo Mediador/metabolismo , Fenotipo , Alelos , Sustitución de Aminoácidos , Facies , Femenino , Genes Ligados a X , Genotipo , Humanos , Masculino , Complejo Mediador/química , Modelos Moleculares , Mutación Missense , Linaje , Conformación Proteica , Relación Estructura-Actividad , Secuenciación del Exoma , Inactivación del Cromosoma XRESUMEN
In 1999, based on a single family, spondyloepimetaphyseal dysplasia (SEMD) with mental retardation (MR) was described as a novel syndrome with probably X-linked recessive inheritance and unknown molecular defect (MIM 300232). Our purpose was to search for the causative defect in the originally described family and in an independently ascertained second family. All patients had slowly progressive neurodegeneration with central and peripheral involvement and identical skeletal dysplasia. Whole exome sequencing performed in two subjects showed a single plausible candidate - the p.Asp237Gly variant in AIFM1 (chr. Xq26.1). The p.Asp237Gly segregated with disease as indicated by linkage analysis [maximum logarithm of odds score (LOD) score at theta 0 for the two families was 3.359]. This variant had not been previously reported and it was predicted to be pathogenic by Polyphen2, SIFT, MutationTaster and Mutation Assessor. AIFM1 encodes mitochondria associated apoptosis-inducing factor. The AIFM1 gene has been linked with COXPD6 encephalomyopathy (MIM 300816), Cowchock syndrome (MIM 310490) and X-linked deafness with neuropathy (DFNX5, MIM 300614), none of which are similar to SEMD-MR. Our results place SEMD as the third instance of a skeletal phenotype associated with a mitochondrial disease (the others being EVEN-PLUS syndrome caused by mutations of HSPA9 and CODAS syndrome due to LONP1 mutations).
Asunto(s)
Factor Inductor de la Apoptosis/genética , Predisposición Genética a la Enfermedad/genética , Enfermedades Mitocondriales/genética , Mutación , Enfermedades Neurodegenerativas/genética , Osteocondrodisplasias/genética , Secuencia de Aminoácidos , Secuencia de Bases , Exoma/genética , Salud de la Familia , Femenino , Enfermedades Genéticas Ligadas al Cromosoma X/diagnóstico , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Humanos , Masculino , Enfermedades Mitocondriales/diagnóstico , Enfermedades Neurodegenerativas/diagnóstico , Osteocondrodisplasias/diagnóstico , Linaje , Fenotipo , Análisis de Secuencia de ADN/métodos , Homología de Secuencia de Aminoácido , SíndromeAsunto(s)
Trastorno Autístico/genética , Deleción Cromosómica , Cromosomas Humanos Par 6/genética , Fucosiltransferasas/genética , Trastornos del Desarrollo del Lenguaje/genética , Receptores Acoplados a Proteínas G/genética , Trastorno Autístico/complicaciones , Niño , Femenino , Humanos , Trastornos del Desarrollo del Lenguaje/etiologíaRESUMEN
Recent advances in molecular cytogenetics enable identification of small chromosomal aberrations that are undetectable by routine chromosome banding in 5-20% of patients with mental retardation/developmental delay (MR/DD) and dysmorphism. The aim of this study was to compare the clinical usefulness of two molecular cytogenetic techniques, metaphase high-resolution comparative genomic hybridization (HR-CGH) and targeted array CGH, also known as Chromosomal Microarray Analysis (CMA). A total of 116 patients with unexplained mild to severe MR and other features suggestive of a chromosomal abnormality with apparently normal or balanced karyotypes were analyzed using HR-CGH (43 patients) and/or CMA (91 patients). Metaphase HR-CGH detected seven interstitial deletions (16.3%). Rare deletions of chromosomes 16 (16p11.2p12.1) and 8 (8q21.11q21.2) were identified. Targeted CMA revealed copy-number changes in 19 of 91 patients (20.8%), among which 11 (11.8%) were clinically relevant, 6 (6.5%) were interpreted as polymorphic variants and 2 (2.1%) were of uncertain significance. The changes varied in size from 0.5 to 12.9 Mb. In summary, our results show that metaphase HR-CGH and array CGH techniques have become important components in cytogenetic diagnostics, particularly for detecting cryptic constitutional chromosome imbalances in patients with MR, in whom the underlying genetic defect is unknown. Additionally, application of both methods together increased the detection rates of genomic imbalances in the tested groups.
Asunto(s)
Anomalías Múltiples/genética , Eliminación de Gen , Duplicación de Gen , Discapacidad Intelectual/genética , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Preescolar , Discapacidades del Desarrollo/genética , Femenino , Humanos , Hibridación Fluorescente in Situ , Cariotipificación , Masculino , MetafaseRESUMEN
In XY males, duplication of any part of the X chromosome except the pseudoautosomal region leads to functional disomy of the corresponding genes. We describe three unrelated male patients with mental retardation (MR), absent or delayed speech, and recurrent infections. Using high-resolution comparative genomic hybridization (HR-CGH), whole genome array comparative genomic hybridization (array CGH), fluorescent in situ hybridization (FISH), and multiplex ligation probe amplification (MLPA), we have identified and characterized two different unbalanced Xq27.3-qter translocations on the Y chromosome (approx. 9 and 12 Mb in size) and one submicroscopic interstitial duplication (approx. 0.3-1.3 Mb) involving the MECP2 gene. Despite the differences in size of the duplicated segments, the patients share a clinical phenotype that overlaps with the features described in patients with MECP2 duplication. Our data confirm previous observations that MECP2 is the most important dosage-sensitive gene responsible for neurologic development in patients with duplications on the distal part of chromosome Xq.
Asunto(s)
Infecciones Bacterianas/genética , Cromosomas Humanos X , Duplicación de Gen , Trastornos del Desarrollo del Lenguaje/genética , Discapacidad Intelectual Ligada al Cromosoma X/genética , Proteína 2 de Unión a Metil-CpG/genética , Mutismo/genética , Adolescente , Infecciones Bacterianas/patología , Niño , Análisis Citogenético , Humanos , Lactante , Trastornos del Desarrollo del Lenguaje/complicaciones , Masculino , Discapacidad Intelectual Ligada al Cromosoma X/complicaciones , Mutismo/complicaciones , RecurrenciaRESUMEN
Haploinsufficiency of SOX9, a master gene in chondrogenesis and testis development, leads to the semi-lethal skeletal malformation syndrome campomelic dysplasia (CD), with or without XY sex reversal. We report on two children with CD and a phenotypically normal father, a carrier of a somatic mosaic SOX9 deletion. This is the first report of a mosaic deletion of SOX9; few familial CD cases with germline and somatic mutation mosaicism have been described. Our findings confirm the utility of aCGH and indicate that for a more accurate estimate of the recurrence risk for a completely penetrant autosomal dominant disorder, parental somatic mosaicism should be considered in healthy parents.
Asunto(s)
Huesos/anomalías , Eliminación de Gen , Proteínas del Grupo de Alta Movilidad/genética , Mosaicismo , Factores de Transcripción/genética , Cromosomas Humanos Par 17 , Salud de la Familia , Padre , Femenino , Proteínas del Grupo de Alta Movilidad/deficiencia , Humanos , Recién Nacido , Mutación , Hibridación de Ácido Nucleico , Penetrancia , Factor de Transcripción SOX9 , Factores de Transcripción/deficienciaRESUMEN
Du Pan syndrome is a rare acromesomelic dysplasia with characteristic clinical and radiographic findings. It is inherited as an autosomal recessive trait. Almost all the patients reported have been from Muslim countries. We report on a female and her child with Du Pan syndrome from a Caucasian, Polish family. Three new heterozygous mutations clustered on one allele of the CDMP1 gene were identified in the affected individuals resulting in the first familial case with dominant Du Pan syndrome. A possible synergistic effect of the cis-acting mutations located in the active domain of the mature CDMP1 protein is likely to be responsible for the clinical expression of the disorder.
Asunto(s)
Anomalías Múltiples/genética , Proteínas Morfogenéticas Óseas/genética , Heterocigoto , Mutación , Secuencia de Bases , Cartilla de ADN , Femenino , Factor 5 de Diferenciación de Crecimiento , Humanos , Masculino , Linaje , Fenotipo , SíndromeAsunto(s)
Aberraciones Cromosómicas , Anomalías Congénitas/patología , Hibridación Fluorescente in Situ/métodos , Discapacidad Intelectual/genética , Telómero/genética , Adolescente , Preescolar , Cromosomas Humanos Par 10/genética , Cromosomas Humanos Par 13/genética , Cromosomas Humanos Par 2/genética , Cromosomas Humanos Par 4/genética , Cromosomas Humanos Par 7/genética , Salud de la Familia , Resultado Fatal , Femenino , Humanos , Discapacidad Intelectual/patología , Cariotipificación , Masculino , Linaje , Translocación GenéticaRESUMEN
Deafness is one of the most frequent congenital hearing impairments. Knowledge of its causes will result in elimination of risk factors and applying prophylactic activities. It is recognized that about 40% of hearing impairments have genetic origin and 80% of these are autosomal recessive. Introducing molecular diagnosis to medical practice makes precise identification of hearing impairment and genetic counseling possible. The authors present results of DNA examination in patients with hereditary deafness, performed at the National Research Institute of Mother and Child in Warsaw. Genetic cause of deafness was confirmed in 60% cases.
Asunto(s)
Conexinas/genética , Trastornos de la Audición/genética , Adolescente , Estudios de Casos y Controles , Niño , Preescolar , Conexina 26 , Conexinas/sangre , Femenino , Regulación de la Expresión Génica/genética , Trastornos de la Audición/sangre , Humanos , Masculino , Reacción en Cadena de la Polimerasa/métodosRESUMEN
We report an analysis of 102 unrelated Polish patients with profound prelingual deafness for mutations in the GJB2 gene (OMIM #220290). Mutations were found in 41/102 (40%) subjects. Among mutated alleles, 35delG was prevalent and present in 88%. In nine alleles, different mutations were found: M34T, Q47X, R184P, and 313del14 (found in 6 patients). The results prove mutations in the GJB2 gene are responsible for much hereditary nonsyndromic deafness in Poland, with a strong prevalence of the 35delG mutation. We have also found a high carrier frequency (1/50) for the 35delG mutation in the Polish population.
Asunto(s)
Conexinas/genética , Sordera/genética , Mutación , Adolescente , Edad de Inicio , Alelos , Sustitución de Aminoácidos , Niño , Conexina 26 , Análisis Mutacional de ADN , Sordera/epidemiología , Femenino , Frecuencia de los Genes , Genotipo , Humanos , Masculino , Mutación Missense , Polonia/epidemiología , Prevalencia , Eliminación de SecuenciaRESUMEN
We report the results of detailed molecular-cytogenetic studies of two isodicentric Y [idic(Y)] chromosomes identified in patients with complex mosaic karyotypes. We used fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) to determine the structure and genetic content of the abnormal chromosomes. In the first patient, classical cytogenetics and FISH analysis with Y chromosome-specific probes showed in peripheral blood lymphocytes a karyotype with 4 cell lines: 45,X[128]/46,X,+idic(Y)(p11.32)[65]/47,XY,+idic(Y)(p11.32)[2]/47,X,+2idic(Y)(p11.32)[1]. No Y chromosome material was found in the removed gonads. For precise characterization of the Yp breakpoint, FISH and fiberFISH analysis, using a telomeric probe and a panel of cosmid probes from the pseudoautosomal region PAR1, was performed. The results showed that the breakpoint maps approximately 1,000 Kb from Ypter. The second idic(Y) chromosome was found in a boy with mild mental retardation, craniofacial anomalies, and the karyotype in lymphocytes 47,X,+idic(Y)(q11.23),+i(Y)(p10)[77]/46,X,+i(Y)(p10)[23]. To our knowledge, such an association has not been previously described. FISH and PCR analysis indicated the presence of at least two copies of the SRY gene in all analyzed cells. Using 17 PCR primers, the Yq breakpoint was shown to map between sY123 (DYS214) and sY121 (DYS212) loci in interval 5O in AZFb region. Possible mechanisms of formation of abnormal Y chromosomes and karyotype-phenotype correlations are discussed.
Asunto(s)
Anomalías Múltiples/genética , Disgenesia Gonadal Mixta/genética , Isocromosomas , Aberraciones Cromosómicas Sexuales/genética , Cromosoma Y/genética , Línea Celular , Análisis Citogenético , ADN/análisis , Femenino , Genotipo , Humanos , Hibridación Fluorescente in Situ/métodos , Recién Nacido , Cariotipificación , Mosaicismo/genética , Fenotipo , Reacción en Cadena de la PolimerasaRESUMEN
A large number of cases with supernumerary marker chromosomes (SMCs) should be compared to achieve a better delineation of karyotype-phenotype correlations. Here we present four phenotypically abnormal patients with autosomal marker chromosomes analysed by fluorescence in situ hybridisation using centromeric, telomeric, and unique sequence probes, as well as forward and reverse painting. We also report the first case, to the best of our knowledge, of an SMC derived from chromosome 5. Furthermore, a marker chromosome 20 in a patient with sex differentiation abnormalities, a double mar(6) in a boy with psychomotor retardation, and the association of r(19) with dup(21q21.2q22.12) are described. Although the mar(6) was very small, the presence of euchromatin was shown, suggesting that the partial trisomy of pericentric region derived sequences is implicated in the aetiology of the abnormal phenotypes.
Asunto(s)
Aberraciones Cromosómicas/genética , Cromosomas Humanos Par 19 , Cromosomas Humanos Par 20 , Cromosomas Humanos Par 5 , Cromosomas Humanos Par 6 , Adolescente , Adulto , Amenorrea/genética , Preescolar , Bandeo Cromosómico , Trastornos de los Cromosomas , Discapacidades del Desarrollo/genética , Edema/genética , Facies , Femenino , Marcadores Genéticos , Genotipo , Humanos , Hibridación Fluorescente in Situ , Lactante , Discapacidad Intelectual/genética , Cariotipificación , Masculino , Fenotipo , Polimorfismo GenéticoRESUMEN
Results of cytogenetic studies, performed in a group of 201 institutionalized mentally retarded males, are presented. At least two cytogenetic methods for eliciting the Xq27.3 fragile site, recommended by the Fourth International Workshop on the Fra X Syndrome were used. A subgroup of 67 out of 201 studied males was also examined using molecular methods. In 6 (2.9%) males fra X syndrome was diagnosed. All cytogenetic positive results were confirmed by molecular analysis. Five patients had full expansion CGG repeats and one had both premutation and full mutation. Postulated frequency of fra X syndrome in Polish population being 0.2-0.4/1,000 males seems to be lower than it could be expected on the basis of previous literature data.
Asunto(s)
Síndrome del Cromosoma X Frágil/epidemiología , Discapacidad Intelectual/genética , Síndrome del Cromosoma X Frágil/genética , Humanos , Institucionalización , Masculino , Mutación , Polonia/epidemiología , Prevalencia , Repeticiones de TrinucleótidosRESUMEN
The case of a 1.5 year old girl with clinical traits of craniofacial dysmorphy, hypotonia, polydactyly and moderate mental retardation is presented. Routine cytogenetic study revealed the presence of a large additional chromosomal fragment associated with the nucleolus organizing region on one of chromosomes 13. The banding pattern suggested the additional fragment was a part of the long arm of this chromosome. The set of clinical symptoms was only partly consistent with those characteristic for trisomy 13q2 and 3. Application of the FISH technique with a chromosome 13 specific library enabled final confirmation of the origin of the extra chromosome fragment from the long arm of chromosome 13. The presented case proves the usefulness of the FISH technique for the diagnosis of chromosomal aberrations and for adequate clinical interpretation of cytogenetic results.
Asunto(s)
Anomalías Múltiples/genética , Cromosomas Humanos Par 13 , Hibridación in Situ/métodos , Trisomía/diagnóstico , Anomalías Craneofaciales/genética , Femenino , Humanos , Lactante , Discapacidad Intelectual , PolidactiliaRESUMEN
The unstable DNA sequence in the FMR1 gene was analyzed in 85 individuals from Polish families with fragile X syndrome in order to characterize mutations responsible for the disease in Poland. In all affected individuals classified on the basis of clinical features and expression of the fragile site at X(q27.3) a large expansion of the unstable sequence (full mutation) was detected. About 5% (2 of 43) of individuals with full mutation did not express the fragile site. Among normal alleles, ranging in size from 20 to 41 CGG repeats, allele with 29 repeats was the most frequent (37%). Transmission of premutated and fully mutated alleles to the offspring was always associated with size increase. No change in repeat number was found when normal alleles were transmitted.
Asunto(s)
Análisis Mutacional de ADN , Síndrome del Cromosoma X Frágil/genética , Proteínas del Tejido Nervioso/genética , Proteínas de Unión al ARN , Alelos , Femenino , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil , Humanos , Masculino , Hibridación de Ácido Nucleico , Reacción en Cadena de la PolimerasaRESUMEN
A group of 30 patients clinically described as having the Prader-Willi Syndrome (PWS) were studied using microsatellites from 15q11-13 and methylation analysis with probe PW71B (D15S63). The patients were categorized according to clinical symptoms. 80% of all patients were informative using molecular and cytogenetic methods. Among 8 patients with an atypical PWS phenotype, 2 showed uniparental disomy, and 2 had a mosaic deletion for 15q. The last 4 atypical and 2 typical patients had neither molecular defects confirmed by microsatellite analysis nor a parent-of-origin-specific methylation pattern for PWS. Our results confirm that methylation pattern analysis provides an additional and alternative microsatellite analysis to diagnose PWS.
Asunto(s)
Cromosomas Humanos Par 15 , Síndrome de Prader-Willi/genética , Adolescente , Adulto , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , PoloniaRESUMEN
One hundred and thirty-four families or individuals with auditory-pigmentary syndromes such as Waardenburg syndrome (WS) or probable neurocristopathies were screened for mutations in the PAX3 and MITF genes. PAX3 mutations were found in 20/25 families with definite Type 1 WS and 1/2 with Type 3 WS, but in none of 23 with definite Type 2 WS or 36 with other neurocristopathies. The PAX3 mutations included substitutions of conserved amino acids in the paired domain or the homeodomain, splice-site mutations, nonsense mutations and frame-shifting insertions or deletions. No phenotype-genotype correlations were noted within WS1 families. With MITF, mutations likely to affect protein function were found in seven families, five of which had definite Type 2 WS. We conclude that Type 1 and Type 3 WS are allelic and are normally caused by loss of function mutations in PAX3; that Type 2 WS is heterogeneous, with about 20% of cases caused by mutations in MITF, and that individuals with auditory, pigmentary or neural crest syndromes which do not fit stringent definitions of Waardenburg syndrome are unlikely to have mutations in either the PAX3 or MITF genes. The molecular pathology of MITF/microphthalmia mutations appears to be different in humans and mice, with gene dosage having more significant effects in humans than in the mouse.