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KBG syndrome (KBGS) is characterized by distinctive facial gestalt, short stature and variable clinical findings. With ageing, some features become more recognizable, allowing a differential diagnosis. We aimed to better characterize natural history of KBGS. In the context of a European collaborative study, we collected the largest cohort of KBGS patients (49). A combined array- based Comparative Genomic Hybridization and next generation sequencing (NGS) approach investigated both genomic Copy Number Variants and SNVs. Intellectual disability (ID) (82%) ranged from mild to moderate with severe ID identified in two patients. Epilepsy was present in 26.5%. Short stature was consistent over time, while occipitofrontal circumference (median value: -0.88 SD at birth) normalized over years. Cerebral anomalies, were identified in 56% of patients and thus represented the second most relevant clinical feature reinforcing clinical suspicion in the paediatric age when short stature and vertebral/dental anomalies are vague. Macrodontia, oligodontia and dental agenesis (53%) were almost as frequent as skeletal anomalies, such as brachydactyly, short fifth finger, fifth finger clinodactyly, pectus excavatum/carinatum, delayed bone age. In 28.5% of individuals, prenatal ultrasound anomalies were reported. Except for three splicing variants, leading to a premature termination, variants were almost all frameshift. Our results, broadening the spectrum of KBGS phenotype progression, provide useful tools to facilitate differential diagnosis and improve clinical management. We suggest to consider a wider range of dental anomalies before excluding diagnosis and to perform a careful odontoiatric/ear-nose-throat (ENT) evaluation in order to look for even submucosal palate cleft given the high percentage of palate abnormalities. NGS approaches, following evidence of antenatal ultrasound anomalies, should include ANKRD11.
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Anomalías Múltiples , Enfermedades del Desarrollo Óseo , Enanismo , Discapacidad Intelectual , Anomalías Dentarias , Embarazo , Femenino , Humanos , Facies , Anomalías Dentarias/genética , Enfermedades del Desarrollo Óseo/genética , Anomalías Múltiples/genética , Anomalías Múltiples/diagnóstico , Discapacidad Intelectual/genética , Discapacidad Intelectual/diagnóstico , Hibridación Genómica Comparativa , Proteínas Represoras/genética , Fenotipo , Enanismo/genética , Pueblo EuropeoRESUMEN
PURPOSE: KBG syndrome (KBGS) is a rare neurodevelopmental syndrome caused by haploinsufficiency of ANKRD11. The childhood phenotype is extensively reported but limited for adults. Thus, we aimed to delineate the clinical features of KBGS. METHODS: We collected physician-reported data of adults with molecularly confirmed KBGS through an international collaboration. Moreover, we undertook a systematic literature review to determine the scope of previously reported data. RESULTS: The international collaboration identified 36 adults from 31 unrelated families with KBGS. Symptoms included mild/borderline intellectual disability (n = 22); gross and/or fine motor difficulties (n = 15); psychiatric and behavioral comorbidities including aggression, anxiety, reduced attention span, and autistic features (n = 26); nonverbal (n = 3), seizures with various seizure types and treatment responses (n = 10); ophthalmological comorbidities (n = 20). Cognitive regression during adulthood was reported once. Infrequent features included dilatation of the ascending aorta (n = 2) and autoimmune conditions (n = 4). Education, work, and residence varied, and the diversity of professional and personal roles highlighted the range of abilities seen. The literature review identified 154 adults reported across the literature, and we have summarized the features across both data sets. CONCLUSION: Our study sheds light on the long-term neurodevelopmental outcomes, seizures, behavioral and psychiatric features, and education, work, and living arrangements for adults with KBGS.
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Discapacidad Intelectual , Fenotipo , Humanos , Adulto , Discapacidad Intelectual/genética , Discapacidad Intelectual/epidemiología , Masculino , Femenino , Persona de Mediana Edad , Adulto Joven , Haploinsuficiencia/genética , Convulsiones/genética , Convulsiones/epidemiología , Médicos , Adolescente , Facies , Anomalías Múltiples , Enfermedades del Desarrollo Óseo , Anomalías DentariasRESUMEN
PURPOSE: Pathogenic LZTR1 variants cause schwannomatosis and dominant/recessive Noonan syndrome (NS). We aim to establish an association between heterozygous loss-of-function (LoF) LZTR1 alleles and isolated multiple café-au-lait macules (CaLMs). METHODS: 849 unrelated participants with multiple CaLMs, lacking pathogenic/likely pathogenic NF1 and SPRED1 variants, underwent RASopathy gene panel sequencing. Data on 125 individuals with heterozygous LZTR1 variants were collected for characterizing their clinical features and the associated molecular spectrum. In vitro functional assessment was performed on a representative panel of missense variants and small in-frame deletions. RESULTS: Analysis revealed heterozygous LZTR1 variants in 6.0% (51/849) of participants, exceeding the general population prevalence. LZTR1-related CaLMs varied in number, displayed sharp or irregular borders, and were generally isolated, but occasionally associated with features recurring in RASopathies. In two families, CaLMs and schwannomas co-occurred. The molecular spectrum mainly consisted of truncating variants, indicating LoF. These variants substantially overlapped with those occurring in schwannomatosis and recessive NS. Functional characterization showed accelerated protein degradation or mislocalization, and failure to downregulate MAPK signaling. CONCLUSION: Our findings expand the phenotypic variability associated with LZTR1 variants, which, in addition to conferring susceptibility to schwannomatosis and causing dominant and recessive NS, occur in individuals with isolated multiple CaLMs.
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We delineate a KMT2E-related neurodevelopmental disorder on the basis of 38 individuals in 36 families. This study includes 31 distinct heterozygous variants in KMT2E (28 ascertained from Matchmaker Exchange and three previously reported), and four individuals with chromosome 7q22.2-22.23 microdeletions encompassing KMT2E (one previously reported). Almost all variants occurred de novo, and most were truncating. Most affected individuals with protein-truncating variants presented with mild intellectual disability. One-quarter of individuals met criteria for autism. Additional common features include macrocephaly, hypotonia, functional gastrointestinal abnormalities, and a subtle facial gestalt. Epilepsy was present in about one-fifth of individuals with truncating variants and was responsive to treatment with anti-epileptic medications in almost all. More than 70% of the individuals were male, and expressivity was variable by sex; epilepsy was more common in females and autism more common in males. The four individuals with microdeletions encompassing KMT2E generally presented similarly to those with truncating variants, but the degree of developmental delay was greater. The group of four individuals with missense variants in KMT2E presented with the most severe developmental delays. Epilepsy was present in all individuals with missense variants, often manifesting as treatment-resistant infantile epileptic encephalopathy. Microcephaly was also common in this group. Haploinsufficiency versus gain-of-function or dominant-negative effects specific to these missense variants in KMT2E might explain this divergence in phenotype, but requires independent validation. Disruptive variants in KMT2E are an under-recognized cause of neurodevelopmental abnormalities.
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Proteínas de Unión al ADN/genética , Epilepsia/etiología , Variación Genética , Heterocigoto , Trastornos del Neurodesarrollo/etiología , Adolescente , Adulto , Niño , Preescolar , Epilepsia/patología , Femenino , Haploinsuficiencia , Humanos , Lactante , Masculino , Trastornos del Neurodesarrollo/patología , Linaje , Fenotipo , Adulto JovenRESUMEN
IQSEC2 mutations are associated with IQSEC2-related intellectual disability (ID). Phenotypic spectrum has been better defined in the last few years by the increasing number of reported cases although the genotype-phenotype relationship for IQSEC2 remains overall complex. As for IQSEC2-related ID a wide phenotypic diversity has been described in Rett syndrome (RTT). Several patients harboring IQSEC2 mutations present with clinical symptoms similar to RTT and some cases meet most of the criteria for classic RTT. With the aim of establishing a genotype-phenotype correlation, we collected data of 16 patients harboring IQSEC2 point mutations (15 of them previously unreported) and of five novel patients carrying CNVs encompassing IQSEC2. Most of our patients surprisingly shared a moderate-to-mild phenotype. The similarities in the clinical course between our mild cases and patients with milder forms of atypical RTT reinforce the hypothesis that also IQSEC2 mutated patients may lay under the wide clinical spectrum of RTT and thus IQSEC2 should be considered in the differential diagnosis. Our data confirm that position, type of variant and gender are crucial for IQSEC2-associated phenotype delineation.
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Factores de Intercambio de Guanina Nucleótido/genética , Discapacidad Intelectual/genética , Síndrome de Rett/genética , Adolescente , Adulto , Niño , Preescolar , Diagnóstico Diferencial , Femenino , Estudios de Asociación Genética , Humanos , Masculino , Persona de Mediana Edad , Mutación Puntual , Síndrome de Rett/diagnóstico , Secuenciación del Exoma , Adulto JovenRESUMEN
OBJECTIVES: Somatic mosaicism of PIK3CA gene is currently recognized as the molecular driver of Klippel-Trenaunay syndrome. However, given the limitation of the current technologies, PIK3CA somatic mutations are detected only in a limited proportion of Klippel-Trenaunay syndrome cases and tissue biopsy remains an invasive high risky, sometimes life-threatening, diagnostic procedure. Next generation sequencing liquid biopsy using cell-free DNA has emerged as an innovative non-invasive approach for early detection and monitoring of cancer. This approach, overcoming the space-time profile constraint of tissue biopsies, opens a new scenario also for others diseases caused by somatic mutations. METHODS: In the present study, we performed a comprehensive analysis of seven patients (four females and three males) with Klippel-Trenaunay syndrome. Blood samples from both peripheral and efferent vein from malformation were collected and cell-free DNA was extracted from plasma. Tissue biopsies from vascular lesions were also collected when available. Cell-free DNA libraries were performed using Oncomine™ Pan-Cancer Cell-Free Assay. Ion Proton for sequencing and Ion Reporter Software for analysis were used (Life Technologies, Carlsbad, CA, USA). RESULTS: Cell-free circulating DNA analysis revealed pathogenic mutations in PIK3CA gene in all patients. The mutational load was higher in plasma obtained from the efferent vein at lesional site (0.81%) than in the peripheral vein (0.64%) leading to conclude for a causative role of the identified variants. Tissue analysis, available for one amputated patient, confirmed the presence of the mutation at the malformation site at a high molecular frequency (14-25%), confirming its causative role. CONCLUSIONS: Our data prove for the first time that the cell-free DNA-next generation sequencing-liquid biopsy, which is currently used exclusively in an oncologic setting, is indeed the most effective tool for Klippel-Trenaunay syndrome diagnosis and tailored personalized treatment.
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Ácidos Nucleicos Libres de Células/genética , Fosfatidilinositol 3-Quinasa Clase I/genética , ADN/genética , Secuenciación de Nucleótidos de Alto Rendimiento , Síndrome de Klippel-Trenaunay-Weber/diagnóstico , Mosaicismo , Mutación , Análisis de Secuencia de ADN , Adulto , Ácidos Nucleicos Libres de Células/sangre , Toma de Decisiones Clínicas , ADN/sangre , Femenino , Marcadores Genéticos , Humanos , Síndrome de Klippel-Trenaunay-Weber/sangre , Síndrome de Klippel-Trenaunay-Weber/genética , Síndrome de Klippel-Trenaunay-Weber/terapia , Biopsia Líquida , Masculino , Persona de Mediana Edad , Fenotipo , Proyectos Piloto , Valor Predictivo de las Pruebas , PronósticoRESUMEN
Retinoblastoma (RB), which represents the most common childhood eye cancer, is caused by biallelic inactivation of RB1 gene. Promoter hypermethylation is quite frequent in RB tissues but conclusive evidence of soma-wide predisposing epimutations is currently scant. Here, 50 patients who tested negative for RB1 germline sequence alterations were screened for aberrant promoter methylation using methylation-specific MLPA. The assay, performed on blood, identified a sporadic patient with methylation of CpG106, absent in parents' DNA. Bisulfite pyrosequencing accurately quantified CpG methylation in blood DNA (mean â¼49%) and also confirmed the aberration in DNA isolated from oral mucosa although at lower levels (mean â¼34%). Using a tag-SNP, methylation was demonstrated to affect the maternal allele. Real-time qPCR demonstrated RB1 transcriptional silencing. In conclusion, we documented that promoter methylation can act as the first "hit" in Knudson's model. This mosaic epimutation mimics the effect of an inactivating mutation and phenocopies RB onset.
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Metilación de ADN/genética , Predisposición Genética a la Enfermedad , Proteínas de Unión a Retinoblastoma/genética , Retinoblastoma/genética , Ubiquitina-Proteína Ligasas/genética , Alelos , Epigénesis Genética , Femenino , Silenciador del Gen , Humanos , Lactante , Masculino , Mutación/genética , Polimorfismo de Nucleótido Simple/genética , Regiones Promotoras Genéticas , Retinoblastoma/patologíaRESUMEN
PURPOSE: To assess the contribution of rare variants in the genetic background toward variability of neurodevelopmental phenotypes in individuals with rare copy-number variants (CNVs) and gene-disruptive variants. METHODS: We analyzed quantitative clinical information, exome sequencing, and microarray data from 757 probands and 233 parents and siblings who carry disease-associated variants. RESULTS: The number of rare likely deleterious variants in functionally intolerant genes ("other hits") correlated with expression of neurodevelopmental phenotypes in probands with 16p12.1 deletion (n=23, p=0.004) and in autism probands carrying gene-disruptive variants (n=184, p=0.03) compared with their carrier family members. Probands with 16p12.1 deletion and a strong family history presented more severe clinical features (p=0.04) and higher burden of other hits compared with those with mild/no family history (p=0.001). The number of other hits also correlated with severity of cognitive impairment in probands carrying pathogenic CNVs (n=53) or de novo pathogenic variants in disease genes (n=290), and negatively correlated with head size among 80 probands with 16p11.2 deletion. These co-occurring hits involved known disease-associated genes such as SETD5, AUTS2, and NRXN1, and were enriched for cellular and developmental processes. CONCLUSION: Accurate genetic diagnosis of complex disorders will require complete evaluation of the genetic background even after a candidate disease-associated variant is identified.
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Trastorno Autístico/genética , Moléculas de Adhesión Celular Neuronal/genética , Tamización de Portadores Genéticos , Metiltransferasas/genética , Proteínas del Tejido Nervioso/genética , Proteínas/genética , Trastorno Autístico/fisiopatología , Proteínas de Unión al Calcio , Cromosomas Humanos Par 16/genética , Cognición/fisiología , Proteínas del Citoesqueleto , Variaciones en el Número de Copia de ADN/genética , Femenino , Regulación de la Expresión Génica/genética , Antecedentes Genéticos , Humanos , Masculino , Moléculas de Adhesión de Célula Nerviosa , Padres , Linaje , Fenotipo , Eliminación de Secuencia/genética , Hermanos , Factores de TranscripciónRESUMEN
Genetic conditions comprise a wide spectrum of different phenotypes, rapidly expanding due to new diagnostic methodologies. Patients' facial features and clinical history represent the key elements leading clinicians to the right diagnosis. CDKL5-early onset epilepsy and Pitt-Hopkins syndrome are two well-known genetic conditions, with a defined phenotype sharing some common characteristics like early-onset epilepsy and hyperventilation episodes. Whilst facial features represent a diagnostic handle in patients with Pitt-Hopkins syndrome, clinical history is crucial in patients carrying a mutation in CDKL5. Here we present the clinical case of a girl evaluated for the first time when she was 24-years old, with a clinical phenotype mimicking Pitt-Hopkins syndrome. Her facial features have become coarser while she was growing up, leading geneticists to raise different clinical hypotheses and to perform several molecular tests before getting the diagnosis of CDKL5-early-epileptic encephalopathy. This finding highlights that although typical facial gestalt has not so far extensively been described in CDKL5 mutated adult patients, peculiar facial features could be present later in life and may let CDKL5-related disorder mimic Pitt Hopkins. Thus, considering atypical Rett syndrome in the differential diagnosis of Pitt Hopkins syndrome could be important to solve complex clinical cases.
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Epilepsia/genética , Hiperventilación/diagnóstico , Discapacidad Intelectual/diagnóstico , Mutación , Fenotipo , Proteínas Serina-Treonina Quinasas/genética , Adulto , Diagnóstico Diferencial , Epilepsia/patología , Facies , Femenino , Humanos , Hiperventilación/genética , Discapacidad Intelectual/genéticaRESUMEN
OBJECTIVE: Germline mutations of either the endothelial cell-specific tyrosine kinase receptor TIE2 or the glomulin (GLMN) gene are responsible for rare inherited venous malformations. Both genes affect the hepatocyte growth factor receptor c-Met, inducing vascular smooth muscle cell migration. Germline mutations of hepatocyte growth factor are responsible for lymphatic malformations, leading to lymphedema. The molecular alteration leading to the abnormal mixed vascular anomaly defined as lymphovenous malformation has remained unknown. METHODS: A group of 4 patients with lymphovenous malformations were selected. Plasma was obtained from both peripheral and efferent vein samples at the vascular malformation site for cell-free DNA extraction. When possible, we analyzed tissue biopsy samples from the vascular lesion. RESULTS: We have demonstrated that in all four patients, an activating MET mutation was present. In three of the four patients, the same pathogenic activating mutation, T1010I, was identified. The mutation was found at the tissue level for the patient with tissue samples available, confirming its causative role in the lymphovenous malformations. CONCLUSIONS: In the present study, we have demonstrated that cell-free DNA next generation sequencing liquid biopsy is able to identify the MET mutations in affected tissues. Although a wider cohort of patients is necessary to confirm its causative role in lymphovenous malformations, these data suggest that lymphovenous malformations could result from postzygotic somatic mutations in genes that are key regulators of lymphatic development. The noninvasiveness of the method avoids any risk of bleeding and can be easily performed in children. We are confident that the present pioneering results have provided a viable alternative in the future for lymphovenous malformation diagnosis, allowing for subsequent therapy tailored to the genetic defect.
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Ácidos Nucleicos Libres de Células/genética , Análisis Mutacional de ADN , Secuenciación de Nucleótidos de Alto Rendimiento , Anomalías Linfáticas/genética , Mutación , Proteínas Proto-Oncogénicas c-met/genética , Malformaciones Vasculares/genética , Adulto , Ácidos Nucleicos Libres de Células/sangre , Femenino , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Humanos , Italia , Biopsia Líquida , Anomalías Linfáticas/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Fenotipo , Valor Predictivo de las Pruebas , Estudios Prospectivos , Proteínas Proto-Oncogénicas c-met/sangre , Medición de Riesgo , Factores de Riesgo , Malformaciones Vasculares/diagnóstico por imagenRESUMEN
[This corrects the article DOI: 10.3389/fonc.2021.649435.].
RESUMEN
Myeloid ecotropic insertion site 2 (MEIS2) gene, encoding a homeodomain-containing transcription factor, has been recently related to syndromic intellectual disability with cleft palate and cardiac defects. Here, we present a male patient, aged 10, with cardiac defects, intellectual disability, facial dysmorphisms and gastroesophageal reflux. Whole exome sequencing revealed a novel de novo nonsense mutation in the MEIS2 gene. This patient represents another reported case with a de novo MEIS2 point mutation and helps to characterize a distinct facial phenotype consisting in low anterior hairline, thin eyebrows, anteverted nares, hypoplastic alae nasi, and M-shape upper lip. Furthermore, these data confirm the role of this gene in cardiac, nervous system development and gastrointestinal function.
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Cardiopatías/genética , Defectos del Tabique Interventricular/genética , Proteínas de Homeodominio/genética , Discapacidad Intelectual/genética , Factores de Transcripción/genética , Niño , Discapacidades del Desarrollo/genética , Discapacidades del Desarrollo/patología , Exoma/genética , Cara/patología , Cardiopatías/patología , Defectos del Tabique Interventricular/patología , Humanos , Discapacidad Intelectual/patología , Masculino , Mutagénesis Insercional/genética , Mutación/genética , Fenotipo , Secuenciación del ExomaRESUMEN
OBJECTIVE: Somatic mosaicism of KRAS gene is currently recognized as the only established molecular basis of arteriovenous malformations (AVM). However, given the limitations of the current technologies, KRAS somatic mutations are detected only in a limited proportion of AVMs and tissue biopsy remains an invasive high risky, sometimes life-threatening, diagnostic procedure. Next-generation sequencing liquid biopsy using cell-free DNA (cfDNA) has emerged as an innovative noninvasive approach for early detection and monitoring of cancer. This approach overcomes the space-time profile constraint of tissue biopsies opens a new scenario for vascular malformations owing to somatic mosaicism. Here, we propose a new approach as a fast noninvasive reliable tool in order to investigate the cfDNA coming from the AVMs. METHODS: A group of five patients suffering from AVM were selected. Blood samples from peripheral vein and efferent vein from vascular malformation were collected and cfDNA was extracted. The cfDNA libraries were performed using Oncomine Pan-Cancer Cell-Free Assay. We used Ion Proton for sequencing and Ion Reporter Software for analysis (Life Technologies, Carlsbad, Calif). RESULTS: In all cases, either G12D or G12V mutations in KRAS were identified. The mutational load was higher in the efferent vein than in peripheral blood, confirming the causative role of the identified mutation at a somatic level. CONCLUSIONS: We demonstrate that cfDNA next-generation sequencing liquid biopsy is able to identify the KRAS mutation detected in affected tissues. Moreover, we have shown that blood sample withdrawal at the lesion site increases variant allele frequency with an order of magnitude above the limit of detection (usually 0.05%), decreasing the risk of a false negative. Finally, the noninvasiveness of the method avoids any risk of bleeding, being easily performed also in children. We propose this technique as the method of choice to better investigate AVMs and consequently to identify the therapy tailored to the genetic defect. CLINICAL RELEVANCE: This article highlights the importance of using liquid biopsy as a new method to investigate the molecular profile of AVMs. In view of the frequent inaccessibility of vascular tissues owing to the invasiveness of solid biopsy and the relative high incidence of biopsies with low diagnostic power, here we evaluated the efficacy of detecting cfDNA fragments released into the bloodstream from the affected tissue cells. Through a simple blood draw from the efferent vein at the vascular malformation site, the liquid biopsy allowed us to identify KRAS pathogenic mutations piloting a personalized therapeutic approach and opening a new scenario for new therapeutic strategies.