RESUMEN

INTRODUCTION: Acute lymphoblastic leukemia (ALL) is characterized by highly genetic heterogeneity, owing to recurrent fusion genes, gene mutations, intragenic deletion, and gene overexpression, which poses significant challenges in clinical detection. RNA sequencing (RNA-seq) is a powerful tool for detecting multiple genetic abnormalities, especially cryptic gene rearrangements, in a single test. METHODS: Sixty samples (B-ALL, n = 49; T-ALL, n = 9; mixed phenotype acute leukemia (MPAL), n = 2) and 20 controls were analyzed by targeted RNA-seq panel of 507 genes developed by our lab. Of these, 16 patients were simultaneously analyzed for gene mutations at the DNA level using a next-generation sequencing panel of 51 genes. Fusion genes, CRLF2 expression, and IKZF1 intragenic deletion were also detected by reverse transcription-polymerase chain reaction (RT-PCR). Karyotype analysis was performed using the R-banding and G-banding technique on bone marrow cells after 24 hours of culture. Partial fusion genes were analyzed using fluorescence in situ hybridization (FISH). RESULTS: Compared with the results of Karyotype analysis, FISH, and RT-PCR, the detection rate of fusion genes by targeted RNA-seq increased from 48.3% to 58.3%, and six unexpected fusion genes were discovered, along with one rare isoform of IKZF1 intragenic deletion (IK10). The DNA sequencing analysis of 16 ALL patients revealed that 96.2% (25/26) of gene mutations identified at the DNA level were also detectable at the RNA level, except for one mutation with a low variant allele fraction. The detection of CRLF2 overexpression exhibited complete concordance between RT-PCR and RNA-seq. CONCLUSION: The utilization of RNA-seq enables the identification of clinically significant genetic abnormalities that may go undetected through conventional detection methods. Its robust analytical performance might bring great application value for clinical diagnosis, prognosis, and therapy in ALL.

Asunto(s)

Factor de Transcripción Ikaros , Mutación , Proteínas de Fusión Oncogénica , Leucemia-Linfoma Linfoblástico de Células Precursoras , Receptores de Citocinas , Humanos , Factor de Transcripción Ikaros/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Masculino , Femenino , Receptores de Citocinas/genética , Niño , Proteínas de Fusión Oncogénica/genética , Adulto , Regulación Leucémica de la Expresión Génica , Adolescente , Preescolar , Persona de Mediana Edad , Análisis de Secuencia de ARN , Eliminación de Gen , Secuenciación de Nucleótidos de Alto Rendimiento

RESUMEN

PURPOSE: Multiple studies suggest an association between DLG2 and neurodevelopmental disorders and indicate the haploinsufficiency of this gene; however, few cases have been thoroughly described. We performed additional studies to confirm this clinical association and DLG2 haploinsufficiency. METHODS: Chromosomal microarray analysis was performed on 11,107 patients at the Cytogenetics Laboratory at the University of Alabama at Birmingham. The Database of Genomic Variants-Gold Standard Variants and the Genome Aggregation Database were selected for the association analysis. Fifty-nine patients from the literature and DECIPHER, all having DLG2 intragenic deletions, were included for comprehensive analysis of the distribution of these deletions. RESULTS: A total of 13 patients with DLG2 intragenic deletions, from 10 families in our cohort, were identified. Nine of 10 probands presented with clinical features of neurodevelopmental disorders. Congenital anomalies and dysmorphism were common in our cohort of patients. Association analysis showed that the frequency of DLG2 deletions in our cohort is significantly higher than those in the Database of Genomic Variants-Gold Standard Variants and the Genome Aggregation Database. Most of DLG2 intragenic deletions identified in 69 unrelated patients from our cohort, the literature, and DECIPHER map to the 5' region of the gene, with a hotspot centered around HPin7, exon 8, and HPin8. CONCLUSION: Our findings reinforce the link between DLG2 intragenic deletions and neurodevelopmental disorders, strongly support the haploinsufficiency of this gene, and indicate that these deletions might also have an association with congenital anomalies and dysmorphism.

Asunto(s)

Trastornos del Neurodesarrollo , Humanos , Trastornos del Neurodesarrollo/genética , Exones/genética , Haploinsuficiencia/genética , Proteínas Supresoras de Tumor/genética , Guanilato-Quinasas/genética

RESUMEN

Mucosal malignant melanoma (MMM) is a rare and aggressive tumor. Despite effective local therapies, tumor recurrence and metastasis remain frequent. The genetics of MMM remain incompletely understood. This study is aimed to identify actionable genetic alterations by next-generation sequencing. Fifteen MMM samples were analyzed by next-generation and Sanger sequencing. Gene copy number alterations were analyzed by MLPA. Mutation status was correlated with pERK, pAKT, and Ki-67 expression and follow-up data. Inactivating mutations and intragenic deletions in neurofibromatosis type-1 (NF1) were identified in 3 and 2 cases, respectively, (in total 5/15, 33%) and activating mutations in NRAS and KRAS (3/15, 20%) cases. Other mutated genes included CDKN2A, APC, ATM, MITF, FGFR1, and FGFR2. BRAF and KIT mutations were not observed. Cases with NF1 alterations tended to have worse overall survival. The mutational status was not associated with pERK, pAKT, or Ki-67 immunostaining. MMM carries frequent gene mutations activating the MAPK pathway, similar to cutaneous melanoma. In contrast, NF1 is the most frequently affected gene. Intragenic NF1 deletions have not been described before and may go undetected by sequencing studies. This finding is clinically relevant as NF1-mutated melanomas have worse survival and could benefit from therapy with immune checkpoint and MEK inhibitors.

Asunto(s)

Biomarcadores de Tumor/genética , Eliminación de Gen , Melanoma/genética , Neurofibromina 1/genética , Neoplasias de los Senos Paranasales/genética , Análisis Mutacional de ADN , Femenino , Predisposición Genética a la Enfermedad , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Masculino , Melanoma/mortalidad , Melanoma/secundario , Melanoma/terapia , Mucosa Nasal/patología , Neoplasias de los Senos Paranasales/mortalidad , Neoplasias de los Senos Paranasales/patología , Neoplasias de los Senos Paranasales/terapia , Fenotipo , Pronóstico

RESUMEN

Birt-Hogg-Dubé syndrome (BHDS, MIM #135150), caused by germline mutations of FLCN gene, is a rare autosomal dominant inherited disorder characterized by skin fibrofolliculomas, renal cancer, pulmonary cysts and spontaneous pneumothorax. The syndrome is considered to be under-diagnosed due to variable and atypical manifestations. Herein we present a BHDS family. Targeted next generation sequencing (NGS) and multiplex ligation-dependent probe amplification (MLPA) revealed a novel FLCN intragenic deletion spanning exons 10-14 in four members including the proband with pulmonary cysts and spontaneous pneumothorax, one member with suspicious skin lesions and a few pulmonary cysts, as well as two asymptomatic family members. In addition, a linkage analysis further demonstrated one member with pulmonary bullae to be a BHDS-ruled-out case, whose bullae presented more likely as an aspect of paraseptal emphysema. Furthermore, the targeted NGS and MLPA data including our previous and present findings were reviewed and analyzed to compare the advantages and disadvantages of the two methods, and a brief review of the relevant literature is included. Considering the capability of the targeted NGS method to detect large intragenic deletions as well as determining deletion junctions, and the occasional false positives of MLPA, we highly recommend targeted NGS to be used for clinical molecular diagnosis in suspected BHDS patients.

RESUMEN

PBX1 encodes the pre-B cell leukemia homeobox transcription factor, a three amino acid loop extension (TALE) homeodomain transcription factor, which forms nuclear complexes with other TALE class homeodomain proteins that ultimately regulate target genes controlling organ patterning during embryogenesis. Heterozygous de novo pathogenic variants in PBX1 resulting in haploinsufficiency are associated with congenital anomalies of the kidneys and urinary tract, most commonly renal hypoplasia, as well as anomalies involving the external ear, branchial arch, heart, and genitalia, and they cause intellectual disability and developmental delay. Affected individuals described thus far have had de novo variants. Here, we report three related individuals with an inherited pathogenic intragenic PBX1 deletion with variable clinical features typical for this syndrome.

Asunto(s)

Coloboma/genética , Predisposición Genética a la Enfermedad , Factor de Transcripción 1 de la Leucemia de Células Pre-B/genética , Insuficiencia Renal/genética , Anomalías Urogenitales/genética , Reflujo Vesicoureteral/genética , Adulto , Niño , Coloboma/diagnóstico , Coloboma/patología , Discapacidades del Desarrollo/diagnóstico , Discapacidades del Desarrollo/genética , Discapacidades del Desarrollo/patología , Femenino , Haploinsuficiencia/genética , Humanos , Lactante , Discapacidad Intelectual/diagnóstico , Discapacidad Intelectual/genética , Discapacidad Intelectual/patología , Masculino , Mutación/genética , Fenotipo , Insuficiencia Renal/diagnóstico , Insuficiencia Renal/patología , Anomalías Urogenitales/patología , Reflujo Vesicoureteral/diagnóstico , Reflujo Vesicoureteral/patología

RESUMEN

Tuberous sclerosis complex (TSC) is a rare autosomal dominant disorder characterized by non-cancerous tumors in multiple organs including the brain, kidney, lung, heart, and skin. We encountered a Japanese family consisting of two siblings (a four-year-old boy and a one-year-old girl) with multiple cardiac rhabdomyomas conveying a high risk of TSC and apparently unaffected sibling (a two-year-old girl) and parents. Whole exome sequencing and application of Integrative Genomic Viewer revealed an identical intragenic TSC1 deletion with the breakpoints on intron 15 and exon 19 in the affected siblings, but not in the apparently unaffected sibling and parents. Subsequently, PCR-based analyses were performed using primers flanking the deletion, showing that the deletion was also present in the father and that the deletion occurred between chr9:135,777,038 (bp) and chr9:135,780,540 (bp) in association with a one bp overlap. Furthermore, RT-PCR analyses were carried out using lymphoblastoid cell lines, revealing a major in-frame insertion/deletion transcript produced by aberrant splicing using a cryptic ″ag″ splice acceptor motif at intron 15 (r.1998_2438delinsTTCATTAGGTGG) and a minor frameshift transcript generated by aberrant splicing between exon 15 and exon 20 (r.1998_2502del, p.Lys666Asnfs*15) in the affected siblings. These findings imply that the intragenic deletion producing two aberrant transcripts was generated as a somatic pathogenic variant involving the germline in the father and was transmitted to the affected siblings.

Asunto(s)

Neoplasias Cardíacas/genética , Mosaicismo , Sitios de Empalme de ARN , Rabdomioma/genética , Proteína 1 del Complejo de la Esclerosis Tuberosa/genética , Línea Celular Tumoral , Preescolar , Femenino , Neoplasias Cardíacas/patología , Humanos , Mutación INDEL , Masculino , Linaje , ARN Mensajero/genética , ARN Mensajero/metabolismo , Rabdomioma/patología , Proteína 1 del Complejo de la Esclerosis Tuberosa/metabolismo

RESUMEN

We report the case of a girl with Asparagine synthetase deficiency, an autosomal recessive metabolic disorder characterized by severe microcephaly and epileptic encephalopathy secondary to pathogenic variants in the ASNS gene. Genetic explorations found a deletion of ASNS and a missense variant on the other allele detected respectively by array comparative genomic hybridization (CGH) and Sanger sequencing. Amino acid analysis provided a biochemical confirmation. Previous cases of Asparagine synthetase deficiency were diagnosed though exome Sequencing. The combination of several techniques (array CGH, sequencing, and biochemical analysis) improves the opportunity to provide accurate diagnosis.

RESUMEN

BACKGROUND: Androgen receptor variants (AR-vs), especially AR-v7 and AR-v 5, 6, and 7 exon-skipped (AR-v567es), are reportedly key players in the development of castration-resistant prostate cancer (CRPC). We previously established a mouse xenograft model (JDCaP) from a metastatic skin lesion from a Japanese patient with CRPC and that was revealed to exhibit androgen sensitivity. In the present study, we established multiple castration-resistant xenograft models from JDCaP mice to investigate the biological features of CRPC. METHODS: Tissue from JDCaP mice was transplanted into male and female nude mice, and after serial passaging, castration-resistant sublines (JDCaP-CR2M and JDCaP-CR4M in male mice, JDCaP-CR2F and JDCaP-CR4F in female mice) were established. We investigated anti-androgen and testosterone sensitivity and the messenger RNA expression pattern of full-length AR and AR-vs. In addition, we compared AR protein levels of patient specimens among primary, local-recurrent, and two skin-metastatic tumors. RESULTS: All JDCaP-CR sublines showed continuous growth following the administration of bicalutamide, although the effects of testosterone varied among sublines. Parental JDCaP and JDCaP-CR2M, JDCaP-CR4M, and JDCaP-CR4F sublines expressed AR-v7, whereas JDCaP-CR2F exhibited elevated AR-v567es expression resulting from genomic deletion, which was confirmed by DNA sequencing. Moreover, we confirmed AR-v7 expression in the tumor of the original patient after androgen-deprivation therapy. CONCLUSIONS: Each JDCaP-CR subline showed different AR-v-expression patterns, with JDCaP-CR2F expressing AR-v567es due to genomic deletion. Our results indicated that AR-vs emerged after androgen-deprivation therapy and appeared essential for acquisition of castration resistance.

Asunto(s)

Neoplasias de la Próstata Resistentes a la Castración/tratamiento farmacológico , Neoplasias de la Próstata Resistentes a la Castración/metabolismo , Neoplasias de la Próstata/tratamiento farmacológico , Neoplasias de la Próstata/metabolismo , Receptores Androgénicos/biosíntesis , Antagonistas de Andrógenos/farmacología , Anilidas/farmacología , Animales , Antineoplásicos/farmacología , Femenino , Perfilación de la Expresión Génica , Xenoinjertos , Humanos , Masculino , Ratones Endogámicos BALB C , Ratones Desnudos , Nitrilos/farmacología , Neoplasias de la Próstata/genética , Neoplasias de la Próstata Resistentes a la Castración/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores Androgénicos/genética , Testosterona/farmacología , Compuestos de Tosilo/farmacología

RESUMEN

INTRODUCTION: Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism due to ATP7B pathogenic mutations. Disease manifestations can be prevented if early diagnosis and effective treatment are given. Direct sequencing is routinely used to confirm WD diagnosis, but cannot identify gross rearrangements. METHODS: Sanger sequencing of ATP7B was performed in 142 newly recruited WD index patients. The clinical effects of identified variants were classified according to American College of Medical Genetics and Genomics (ACMG) standards and guidelines. Multiplex ligation-dependent probe amplification (MLPA) was performed in 168 WD cases with clinical WD unexplained by Sanger sequencing, selected from our total case series of 774 WD patients. After identifying gross rearrangements within ATP7B, the breakpoints were determined by long-range PCR and direct sequencing. RESULTS: In the 142 WD patients, we identified 71 sequence alterations in ATP7B, of which 15 were novel; 14 of these were classified as 'pathogenic' or 'likely pathogenic', including 2 intronic variants affecting splice sites. In 6 of 168 WD patients, MLPA identified four heterozygous gross ATP7B deletions. One was a whole gene deletion, and three were intragenic deletions which were mapped to breakpoint locations, revealing non-homologous end joining. CONCLUSION: Intragenic deletions are responsible for WD and non-homologous end joining could be the pathogenesis, therefore the detection of intragenic deletions should be included in comprehensive genetic testing for WD.

Asunto(s)

Pueblo Asiatico/genética , ATPasas Transportadoras de Cobre/genética , Degeneración Hepatolenticular/diagnóstico , Degeneración Hepatolenticular/genética , Mutación/genética , Eliminación de Secuencia/genética , Adolescente , Adulto , Niño , Femenino , Variación Genética/genética , Humanos , Masculino , Adulto Joven

RESUMEN

GAPO syndrome is a very rare disorder characterized by growth retardation, alopecia, pseudoanodontia and progressive optic atrophy. It is caused by biallelic mutations in the ANTXR1 gene. Herein, we describe the clinical and molecular findings of seven new patients with GAPO syndrome. Our patients presented with the characteristic clinical features of the syndrome except for one patient who did not display total alopecia till the age of two years. Strikingly, optic atrophy and glaucoma were observed in all patients and one patient showed keratopathy in addition. Moreover, craniosynstosis was an unusual associated finding in one patient. Mutational analysis of ANTXR1 gene identified five novel homozygous mutations including two frameshift, two splice site and a large intragenic deletion of exon 3. Our results reinforce the clinical characteristics of the syndrome, expand the mutational spectrum and provide more insights into the role of the ANTXR1 protein in the regulation of extracellular matrix.

Asunto(s)

Alopecia/genética , Anodoncia/genética , Trastornos del Crecimiento/genética , Proteínas de Microfilamentos/genética , Atrofias Ópticas Hereditarias/genética , Atrofia Óptica/genética , Receptores de Superficie Celular/genética , Eliminación de Secuencia/genética , Alopecia/patología , Anodoncia/patología , Niño , Preescolar , Femenino , Trastornos del Crecimiento/patología , Homocigoto , Humanos , Lactante , Masculino , Atrofias Ópticas Hereditarias/patología , Atrofia Óptica/patología

RESUMEN

PURPOSE: We investigated the frequencies and characteristics of intragenic copy-number variants (CNVs) in a deep sampling of disease genes associated with monogenic disorders. METHODS: Subsets of 1507 genes were tested using next-generation sequencing to simultaneously detect sequence variants and CNVs in >143,000 individuals referred for genetic testing. We analyzed CNVs in gene panels for hereditary cancer syndromes and cardiovascular, neurological, or pediatric disorders. RESULTS: Our analysis identified 2844 intragenic CNVs in 384 clinically tested genes. CNVs were observed in 1.9% of the entire cohort but in a disproportionately high fraction (9.8%) of individuals with a clinically significant result. CNVs accounted for 4.7-35% of pathogenic variants, depending on clinical specialty. Distinct patterns existed among CNVs in terms of copy number, location, exons affected, clinical classification, and genes affected. Separately, analysis of de-identified data for 599 genes unrelated to the clinical phenotype yielded 4054 CNVs. Most of these CNVs were novel rare events, present as duplications, and enriched in genes associated with recessive disorders or lacking loss-of-function mutational mechanisms. CONCLUSION: Universal intragenic CNV analysis adds substantial clinical sensitivity to genetic testing. Clinically relevant CNVs have distinct properties that distinguish them from CNVs contributing to normal variation in human disease genes.

Asunto(s)

Variaciones en el Número de Copia de ADN/genética , Estudios de Asociación Genética , Enfermedades Genéticas Congénitas/genética , Predisposición Genética a la Enfermedad , Hibridación Genómica Comparativa , Exones/genética , Enfermedades Genéticas Congénitas/patología , Pruebas Genéticas , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Fenotipo

RESUMEN

PURPOSE: TANGO2-related disorders were first described in 2016 and prior to this publication, only 15 individuals with TANGO2-related disorder were described in the literature. Primary features include metabolic crisis with rhabdomyolysis, encephalopathy, intellectual disability, seizures, and cardiac arrhythmias. We assess whether genotype and phenotype of TANGO2-related disorder has expanded since the initial discovery and determine the efficacy of exome sequencing (ES) as a diagnostic tool for detecting variants. METHODS: We present a series of 14 individuals from 11 unrelated families with complex medical and developmental histories, in whom ES or microarray identified compound heterozygous or homozygous variants in TANGO2. RESULTS: The initial presentation of patients with TANGO2-related disorders can be variable, including primarily neurological presentations. We expand the phenotype and genotype for TANGO2, highlighting the variability of the disorder. CONCLUSION: TANGO2-related disorders can have a more diverse clinical presentation than previously anticipated. We illustrate the utility of routine ES data reanalysis whereby discovery of novel disease genes can lead to a diagnosis in previously unsolved cases and the need for additional copy-number variation analysis when ES is performed.

Asunto(s)

Translocador Nuclear del Receptor de Aril Hidrocarburo/genética , Adolescente , Translocador Nuclear del Receptor de Aril Hidrocarburo/fisiología , Encefalopatías/genética , Niño , Preescolar , Variaciones en el Número de Copia de ADN/genética , Discapacidades del Desarrollo/genética , Exoma , Familia , Femenino , Genotipo , Humanos , Discapacidad Intelectual/genética , Masculino , Linaje , Fenotipo , Convulsiones/genética , Secuenciación del Exoma/métodos

RESUMEN

Members of the neurexin gene family, neurexin 1 (NRXN1), neurexin 2 (NRXN2), and neurexin 3 (NRXN3) encode important components of synaptic function implicated in autism and other neurodevelopmental/neuropsychiatric disorders. Loss of function variants have been reported predominantly in NRXN1, with fewer such variants detected in NRXN2 and NRXN3. Evidence for segregating NRNX3 variants has particularly been lacking. Here, we report identification by chromosomal microarray analysis of a rare exonic deletion affecting the NRXN3 alpha isoform in a three-generation Chinese family. The proband, a 7-year-old boy, presented with motor and language delay and met the clinical diagnostic criteria for autism. He also presented with moderate intellectual disability, attention-deficit hyperactivity disorder and facial dysmorphic features. The mother and maternal grandfather, both deletion carriers, presented with variable degrees of language and communication difficulties, as well as neuropsychiatric problems such as schizophrenia and temper tantrums. A compilation of sporadic cases with deletions involving part or all of NRXN3 revealed that 9 of 23 individuals (39%) displayed features of autism. The evidence for cosegregation in our family further supports a role for NRXN3 in autism and neurodevelopmental/neuropsychiatric disorders but demonstrates intrafamily variable expressivity due to this NRXN3 deletion, with schizophrenia and facial dysmorphism being potential novel features of NRXN3 haploinsufficiency.

Asunto(s)

Trastorno del Espectro Autista/genética , Proteínas del Tejido Nervioso/genética , Adulto , Pueblo Asiatico/genética , Trastorno Autístico/genética , Niño , China , Exones , Familia , Femenino , Eliminación de Gen , Heterocigoto , Humanos , Discapacidad Intelectual/genética , Trastornos del Desarrollo del Lenguaje/genética , Masculino , Proteínas del Tejido Nervioso/metabolismo , Trastornos del Neurodesarrollo/genética , Pruebas Neuropsicológicas , Linaje , Isoformas de Proteínas , Eliminación de Secuencia , Secuenciación del Exoma/métodos

RESUMEN

Congenital malformations affecting the neural tube can present as isolated malformations or occur in association with other developmental abnormalities and syndromes. Using high-resolution copy number screening in 66 fetuses with neural tube defects, we identified six fetuses with likely pathogenic mutations, three aneuploidies (one trisomy 13 and two trisomy 18) and three deletions previously reported in NTDs (one 22q11.2 deletion and two 1p36 deletions) corresponding to 9% of the cohort. In addition, we identified five rare deletions and two duplications of uncertain significance including a rare intragenic heterozygous in-frame WDR63 deletion in a fetus with occipital encephalocele. Whole genome sequencing verified the deletion and excluded known pathogenic variants. The deletion spans exons 14-17 resulting in the expression of a protein missing the third and fourth WD-repeat domains. These findings were supported by CRISPR/Cas9-mediated somatic deletions in zebrafish. Injection of two different sgRNA-pairs targeting relevant intronic regions resulted in a deletion mimicking the human deletion and a concomitant increase of abnormal embryos with body and brain malformations (41%, n = 161 and 62%, n = 224, respectively), including a sac-like brain protrusion (7% and 9%, P < 0.01). Similar results were seen with overexpression of RNA encoding the deleted variant in zebrafish (total abnormal; 46%, n = 255, P < 0.001) compared with the overexpression of an equivalent amount of wild-type RNA (total abnormal; 3%, n = 177). We predict the in-frame WDR63 deletion to result in a dominant negative or gain-of-function form of WDR63. These are the first findings supporting a role for WDR63 in encephalocele formation.

Asunto(s)

Encefalocele/genética , Exones/genética , Eliminación de Gen , Péptidos y Proteínas de Señalización Intracelular/fisiología , Animales , Proteína 9 Asociada a CRISPR , Repeticiones Palindrómicas Cortas Agrupadas y Regularmente Espaciadas , Estudios de Cohortes , Variaciones en el Número de Copia de ADN , Dineínas , Femenino , Feto , Marcación de Gen , Pruebas Genéticas , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Intrones/genética , Masculino , Pez Cebra/genética

RESUMEN

Angelman syndrome (AS) is characterised by developmental delay, lack of speech, seizures, a characteristic behavioural profile with a happy demeanour, microcephaly, and ataxia. More than two-thirds of cases are due to an approximately 5-Mb interstitial deletion of the imprinted region 15q11.2q13, which is usually de novo. The rest are associated with point mutations in the UBE3A gene, imprinting defects, and paternal uniparental disomy. Small intragenic UBE3A deletions have rarely been described. They are usually maternally inherited, increasing the recurrence risk to 50%, and may be missed by conventional testing (methylation studies and UBE3A gene sequencing). We describe a boy with AS due to an 11.7-kb intragenic deletion. The deletion was identified by array-CGH and was subsequently detected in his affected first cousin and unaffected maternal grandfather, mother, and aunt, confirming the silencing of the paternal allele. The patient had developmental delay, speech impairment, a happy demeanour, microcephaly, and an abnormal EEG, but no seizures by the age of 4 years. Delineation of the underlying genetic mechanism is of utmost importance for reasons of genetic counselling, as well as appropriate management and prognosis. Alternative techniques, such as array-CGH and MLPA, are necessary when conventional testing for AS has failed to identify the underlying genetic mechanism.

Asunto(s)

Síndrome de Angelman/genética , Exones/genética , Herencia Materna/genética , Eliminación de Secuencia , Ubiquitina-Proteína Ligasas/genética , Alelos , Síndrome de Angelman/fisiopatología , Braquidactilia/diagnóstico , Braquidactilia/genética , Braquidactilia/fisiopatología , Preescolar , Aberraciones Cromosómicas , Cromosomas Humanos Par 15/genética , Dedos/anomalías , Humanos , Hipertelorismo/diagnóstico , Hipertelorismo/genética , Hipertelorismo/fisiopatología , Discapacidad Intelectual/genética , Masculino , Fenotipo , Estrabismo/diagnóstico , Estrabismo/genética , Estrabismo/fisiopatología

RESUMEN

Relatively little is known about the neurobiological basis of speech disorders although genetic determinants are increasingly recognized. The first gene for primary speech disorder was FOXP2, identified in a large, informative family with verbal and oral dyspraxia. Subsequently, many de novo and familial cases with a severe speech disorder associated with FOXP2 mutations have been reported. These mutations include sequencing alterations, translocations, uniparental disomy, and genomic copy number variants. We studied eight probands with speech disorder and their families. Family members were phenotyped using a comprehensive assessment of speech, oral motor function, language, literacy skills, and cognition. Coding regions of FOXP2 were screened to identify novel variants. Segregation of the variant was determined in the probands' families. Variants were identified in two probands. One child with severe motor speech disorder had a small de novo intragenic FOXP2 deletion. His phenotype included features of childhood apraxia of speech and dysarthria, oral motor dyspraxia, receptive and expressive language disorder, and literacy difficulties. The other variant was found in a family in two of three family members with stuttering, and also in the mother with oral motor impairment. This variant was considered a benign polymorphism as it was predicted to be non-pathogenic with in silico tools and found in database controls. This is the first report of a small intragenic deletion of FOXP2 that is likely to be the cause of severe motor speech disorder associated with language and literacy problems.

Asunto(s)

Apraxias/genética , Disartria/genética , Factores de Transcripción Forkhead/genética , Eliminación de Secuencia , Adolescente , Adulto , Secuencia de Bases , Niño , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Destreza Motora , Linaje , Habla , Adulto Joven

RESUMEN

LWD is associated to SHOX haploinsufficiency, in most cases, due to gene deletion. Generally FISH and microsatellite analysis are used to identify SHOX deletion. MLPA is a new method of detecting gene copy variation, allowing simultaneous analysis of several regions. Here we describe the presence of a SHOX intragenic deletion in a family with LWD, analyzed through different methodologies. Genomic DNA of 11 subjects from one family were studied by microsatellite analysis, direct sequencing and MLPA. FISH was performed in two affected individuals. Microsatellite analysis showed that all affected members shared the same haplotype suggesting the involvement of SHOX. MLPA detected an intragenic deletion involving exons IV-VIa, which was not detected by FISH and microsatellite analysis. In conclusion, the MLPA technique was proved to be the best solution on detecting this small deletion, it has the advantage of being less laborious also allowing the analysis of several regions simultaneously.

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Discondrosteose de Léri-Weill (DLW) está associada à haploinsuficiência do gene SHOX resultante, principalmente, de deleções. Geralmente, o FISH e a análise de microssatélites são os métodos utilizados para a identificação destas deleções. MLPA é um novo método para detectar variações do número de cópias gênicas, permitindo uma análise simultânea de várias regiões. Aqui, descrevemos uma pequena deleção intragênica no SHOX em uma família com DLW analisada por diferentes metodologias. DNA genômico de 11 membros de uma família foram estudados por microssatélites, seqüenciamento direto e MLPA. FISH foi realizado em dois indivíduos afetados. Os microssatélites demonstraram que todos os membros afetados apresentavam o mesmo haplotipo, sugerindo o envolvimento do SHOX. MLPA identificou uma deleção intragênica envolvendo os éxons IV-VIa, que não foi detectada pelo FISH e pelos microssatélites. Conclui-se que o MLPA demonstrou melhor resolução para detectar esta pequena deleção, com a vantagem de ser menos trabalhoso e permitir a análise de várias regiões simultaneamente.

Asunto(s)

Niño , Femenino , Humanos , Masculino , Sondas de ADN/genética , Eliminación de Gen , Proteínas de Homeodominio/genética , Técnicas de Amplificación de Ácido Nucleico/métodos , Osteocondrodisplasias/genética , Estudios de Casos y Controles , Repeticiones de Microsatélite , Linaje , Análisis de Secuencia de ADN/métodos