ABSTRACT
El síndrome de Williams-Beuren (WBS) es un trastorno del desarrollo neurológico que incluye diferentes manifestaciones clínicas como estenosis aórtica supravalvular, lesiones cerebrovasculares, retraso en el crecimiento, rasgos faciales "élficos" y retraso mental. Es causado por una microdeleción heterocigótica de genes contiguos en la banda cromosómica 7q11.23, generando un cambio en el número de copias (CNV) de esta región crítica. Los pacientes presentan una amplia manifestación clínica y variada expresión fenotípica. La confirmación de la sospecha clínica es esencial para el seguimiento clínico del paciente y el asesoramiento genético de la familia. La técnica estándar para la detección de WBS es la hibridización fluorescente in situ. En los últimos años la metodología MLPA (Multiplex Ligation dependent Probe Amplification) ha sido incorporada a los laboratorios diagnósticos para la detección de CNV relacionados con distintas enfermedades, incluyendo WBS. El objetivo de este trabajo fue confirmar el diagnóstico clínico de WBS en un niño, utilizando la técnica de MLPA. Los ensayos por MLPA permitieron detectar la deleción de los genes CYLN2, FZD9, STX1A, ELN, LIMK1y RFC2. En regiones geográficas donde la determinación por FISH (Fluorescence In Situ Hybridization) no está disponible para esta enfermedad, la metodología MLPA ha permitido confirmar el diagnóstico clínico y detectar los genes involucrados en la alteración. Hasta nuestro conocimiento no hay otros casos publicados sobre síndrome de WB detectado por la técnica MLPA en la Argentina.
Williams-Beuren syndrome (WBS) is a rare developmental disorder characterized by distinctive facial, neurobehavioral, and cardiovascular features. WBS is caused by a heterozygous contiguous gene microdeletion of the WBS crítical region on chromosome 7q11.23. Confirmation of clinical suspicion is essential for clinical monitoring of the patient and genetic counseling of the family. Fluorescence in situ hybridization (FISH) is considered the gold standard technique for detecting WBS. Multiplex ligation-dependent probe amplification (MLPA) has been introduced into DNA diagnostic laboratories for the detection of copy number variations in several diseases including WBS. The objective of this study was to confirm, by MLPA, the clinical diagnosis of WBS in a pediatric patient. This technique allowed to detect the deletion of CYLN2, FZD9, STX1A, ELN, LIMK1 and RFC2 genes. In geographic regions were the detection by F ISH is not available for this disease, the MLPA methodology allowed to confirm the clinic diagnostic of WBS. To our knowledge this is the first report demonstrating the confirmation of WBS by MLPA in Argentina.
Subject(s)
Child, Preschool , Humans , Male , Multiplex Polymerase Chain Reaction , Williams Syndrome/diagnosis , Aortic Stenosis, Supravalvular/diagnosis , Gene Dosage , In Situ Hybridization, Fluorescence , Williams Syndrome/geneticsABSTRACT
El síndrome de Williams-Beuren (WBS) es un trastorno del desarrollo neurológico que incluye diferentes manifestaciones clínicas como estenosis aórtica supravalvular, lesiones cerebrovasculares, retraso en el crecimiento, rasgos faciales "élficos" y retraso mental. Es causado por una microdeleción heterocigótica de genes contiguos en la banda cromosómica 7q11.23, generando un cambio en el número de copias (CNV) de esta región crítica. Los pacientes presentan una amplia manifestación clínica y variada expresión fenotípica. La confirmación de la sospecha clínica es esencial para el seguimiento clínico del paciente y el asesoramiento genético de la familia. La técnica estándar para la detección de WBS es la hibridización fluorescente in situ. En los últimos años la metodología MLPA (Multiplex Ligation dependent Probe Amplification) ha sido incorporada a los laboratorios diagnósticos para la detección de CNV relacionados con distintas enfermedades, incluyendo WBS. El objetivo de este trabajo fue confirmar el diagnóstico clínico de WBS en un niño, utilizando la técnica de MLPA. Los ensayos por MLPA permitieron detectar la deleción de los genes CYLN2, FZD9, STX1A, ELN, LIMK1y RFC2. En regiones geográficas donde la determinación por FISH (Fluorescence In Situ Hybridization) no está disponible para esta enfermedad, la metodología MLPA ha permitido confirmar el diagnóstico clínico y detectar los genes involucrados en la alteración. Hasta nuestro conocimiento no hay otros casos publicados sobre síndrome de WB detectado por la técnica MLPA en la Argentina.(AU)
Williams-Beuren syndrome (WBS) is a rare developmental disorder characterized by distinctive facial, neurobehavioral, and cardiovascular features. WBS is caused by a heterozygous contiguous gene microdeletion of the WBS crítical region on chromosome 7q11.23. Confirmation of clinical suspicion is essential for clinical monitoring of the patient and genetic counseling of the family. Fluorescence in situ hybridization (FISH) is considered the gold standard technique for detecting WBS. Multiplex ligation-dependent probe amplification (MLPA) has been introduced into DNA diagnostic laboratories for the detection of copy number variations in several diseases including WBS. The objective of this study was to confirm, by MLPA, the clinical diagnosis of WBS in a pediatric patient. This technique allowed to detect the deletion of CYLN2, FZD9, STX1A, ELN, LIMK1 and RFC2 genes. In geographic regions were the detection by F ISH is not available for this disease, the MLPA methodology allowed to confirm the clinic diagnostic of WBS. To our knowledge this is the first report demonstrating the confirmation of WBS by MLPA in Argentina.(AU)
Subject(s)
Child, Preschool , Humans , Male , Multiplex Polymerase Chain Reaction , Williams Syndrome/diagnosis , Aortic Stenosis, Supravalvular/diagnosis , Gene Dosage , In Situ Hybridization, Fluorescence , Williams Syndrome/geneticsABSTRACT
Williams-Beuren syndrome (WBS) is a rare developmental disorder characterized by distinctive facial, neurobehavioral, and cardiovascular features. WBS is caused by a heterozygous contiguous gene microdeletion of the WBS crítical region on chromosome 7q11.23. Confirmation of clinical suspicion is essential for clinical monitoring of the patient and genetic counseling of the family. Fluorescence in situ hybridization (FISH) is considered the gold standard technique for detecting WBS. Multiplex ligation-dependent probe amplification (MLPA) has been introduced into DNA diagnostic laboratories for the detection of copy number variations in several diseases including WBS. The objective of this study was to confirm, by MLPA, the clinical diagnosis of WBS in a pediatric patient. This technique allowed to detect the deletion of CYLN2, FZD9, STX1A, ELN, LIMK1 and RFC2 genes. In geographic regions were the detection by FISH is not available for this disease, the MLPA methodology allowed to confirm the clinic diagnostic of WBS. To our knowledge this is the first report demonstrating the confirmation of WBS by MLPA in Argentina.
Subject(s)
Multiplex Polymerase Chain Reaction , Williams Syndrome/diagnosis , Aortic Stenosis, Supravalvular/diagnosis , Child, Preschool , Gene Dosage , Humans , In Situ Hybridization, Fluorescence , Male , Williams Syndrome/geneticsABSTRACT
Williams-Beuren syndrome (WBS) is a rare developmental disorder characterized by distinctive facial, neurobehavioral, and cardiovascular features. WBS is caused by a heterozygous contiguous gene microdeletion of the WBS crítical region on chromosome 7q11.23. Confirmation of clinical suspicion is essential for clinical monitoring of the patient and genetic counseling of the family. Fluorescence in situ hybridization (FISH) is considered the gold standard technique for detecting WBS. Multiplex ligation-dependent probe amplification (MLPA) has been introduced into DNA diagnostic laboratories for the detection of copy number variations in several diseases including WBS. The objective of this study was to confirm, by MLPA, the clinical diagnosis of WBS in a pediatric patient. This technique allowed to detect the deletion of CYLN2, FZD9, STX1A, ELN, LIMK1 and RFC2 genes. In geographic regions were the detection by FISH is not available for this disease, the MLPA methodology allowed to confirm the clinic diagnostic of WBS. To our knowledge this is the first report demonstrating the confirmation of WBS by MLPA in Argentina.
Subject(s)
Multiplex Polymerase Chain Reaction , Williams Syndrome/diagnosis , Aortic Stenosis, Supravalvular/diagnosis , Child, Preschool , Gene Dosage , Humans , In Situ Hybridization, Fluorescence , Male , Williams Syndrome/geneticsABSTRACT
Allan-Herndon-Dudley syndrome was among the first of the X-linked mental retardation syndromes to be described (in 1944) and among the first to be regionally mapped on the X chromosome (in 1990). Six large families with the syndrome have been identified, and linkage studies have placed the gene locus in Xq13.2. Mutations in the monocarboxylate transporter 8 gene (MCT8) have been found in each of the six families. One essential function of the protein encoded by this gene appears to be the transport of triiodothyronine into neurons. Abnormal transporter function is reflected in elevated free triiodothyronine and lowered free thyroxine levels in the blood. Infancy and childhood in the Allan-Herndon-Dudley syndrome are marked by hypotonia, weakness, reduced muscle mass, and delay of developmental milestones. Facial manifestations are not distinctive, but the face tends to be elongated with bifrontal narrowing, and the ears are often simply formed or cupped. Some patients have myopathic facies. Generalized weakness is manifested by excessive drooling, forward positioning of the head and neck, failure to ambulate independently, or ataxia in those who do ambulate. Speech is dysarthric or absent altogether. Hypotonia gives way in adult life to spasticity. The hands exhibit dystonic and athetoid posturing and fisting. Cognitive development is severely impaired. No major malformations occur, intrauterine growth is not impaired, and head circumference and genital development are usually normal. Behavior tends to be passive, with little evidence of aggressive or disruptive behavior. Although clinical signs of thyroid dysfunction are usually absent in affected males, the disturbances in blood levels of thyroid hormones suggest the possibility of systematic detection through screening of high-risk populations.
