RESUMEN
Genomic imprinting, the monoallelic and parent-of-origin-dependent expression of a subset of genes, is required for normal development, and its disruption leads to human disease. Imprinting defects can involve isolated or multilocus epigenetic changes that may have no evident genetic cause, or imprinting disruption can be traced back to alterations of cis-acting elements or trans-acting factors that control the establishment, maintenance and erasure of germline epigenetic imprints. Recent insights into the dynamics of the epigenome, including the effect of environmental factors, suggest that the developmental outcomes and heritability of imprinting disorders are influenced by interactions between the genome, the epigenome and the environment in germ cells and early embryos.
Asunto(s)
Metilación de ADN , Enfermedades Genéticas Congénitas/genética , Genoma Humano , Impresión Genómica , Animales , HumanosRESUMEN
PLAGL1 is one of a group of imprinted genes, whose altered expression causes imprinting disorders impacting growth, development, metabolism, and behavior. PLAGL1 over-expression causes transient neonatal diabetes mellitus (TNDM type 1) and, based on murine models, under-expression would be expected to cause growth restriction. However, only some reported individuals with upd(6)mat have growth restriction, giving rise to uncertainty about the role of PLAGL1 in human growth. Here we report three individuals investigated for growth restriction, two with upd(6)mat and one with a mosaic deletion of the paternally-inherited allele of PLAGL1. These cases add to evidence of its involvement in pre- and early post-natal human growth.
Asunto(s)
Impresión Genómica , Disomía Uniparental , Recién Nacido , Humanos , Animales , Ratones , Impresión Genómica/genética , Factores de Transcripción/genética , Proteínas de Ciclo Celular/genética , Proteínas Supresoras de Tumor/genéticaRESUMEN
BACKGROUND: Silver-Russell syndrome (SRS) is an imprinting disorder characterised by prenatal and postnatal growth restriction, but its clinical features are non-specific and its differential diagnosis is broad. Known molecular causes of SRS include imprinting disturbance, single nucleotide variant (SNV), CNV or UPD affecting several genes; however, up to 40% of individuals with a clinical diagnosis of SRS currently receive no positive molecular diagnosis. METHODS: To determine whether whole-genome sequencing (WGS) could uncover pathogenic variants missed by current molecular testing, we analysed data of 72 participants recruited to the 100,000 Genomes Project within the clinical category of SRS. RESULTS: In 20 participants (27% of the cohort) we identified genetic variants plausibly accounting for SRS. Coding SNVs were identified in genes including CDKN1C, IGF2, IGF1R and ORC1. Maternal-effect variants were found in mothers of five participants, including two participants with imprinting disturbance and one with multilocus imprinting disorder. Two regions of homozygosity were suggestive of UPD involving imprinted regions implicated in SRS and Temple syndrome, and three plausibly pathogenic CNVs were found, including a paternal deletion of PLAGL1. In 48 participants with no plausible pathogenic variant, unbiased analysis of SNVs detected a potential association with STX4. CONCLUSION: WGS analysis can detect UPD, CNV and SNV and is potentially a valuable addition to diagnosis of SRS and related growth-restricting disorders.
Asunto(s)
Anomalías Múltiples , Síndrome de Silver-Russell , Anomalías Múltiples/genética , Metilación de ADN , Femenino , Impresión Genómica/genética , Humanos , Herencia Materna , Embarazo , Síndrome de Silver-Russell/diagnóstico , Síndrome de Silver-Russell/genética , Disomía UniparentalRESUMEN
Germline mutations in fundamental epigenetic regulatory molecules including DNA methyltransferase 3 alpha (DNMT3A) are commonly associated with growth disorders, whereas somatic mutations are often associated with malignancy. We profiled genome-wide DNA methylation patterns in DNMT3A c.2312G > A; p.(Arg771Gln) carriers in a large Amish sibship with Tatton-Brown-Rahman syndrome (TBRS), their mosaic father, and 15 TBRS patients with distinct pathogenic de novo DNMT3A variants. This defined widespread DNA hypomethylation at specific genomic sites enriched at locations annotated as genes involved in morphogenesis, development, differentiation, and malignancy predisposition pathways. TBRS patients also displayed highly accelerated DNA methylation aging. These findings were most marked in a carrier of the AML-associated driver mutation p.Arg882Cys. Our studies additionally defined phenotype-related accelerated and decelerated epigenetic aging in two histone methyltransferase disorders: NSD1 Sotos syndrome overgrowth disorder and KMT2D Kabuki syndrome growth impairment. Together, our findings provide fundamental new insights into aberrant epigenetic mechanisms, the role of epigenetic machinery maintenance, and determinants of biological aging in these growth disorders.
Asunto(s)
Envejecimiento/genética , ADN (Citosina-5-)-Metiltransferasas/genética , Epigénesis Genética , Trastornos del Crecimiento/genética , Mutación , Anomalías Múltiples/genética , Adolescente , Adulto , Amish/genética , Niño , Metilación de ADN , ADN Metiltransferasa 3A , Cara/anomalías , Enfermedades Hematológicas/genética , Humanos , Discapacidad Intelectual/genética , Leucemia Mieloide Aguda/genética , Masculino , Metiltransferasas , Morfogénesis/genética , Síndrome , Enfermedades Vestibulares/genética , Adulto JovenRESUMEN
OBJECTIVE: Silver-Russell syndrome (SRS) causes short stature. Growth hormone (GH) treatment aims to increase adult height. However, data are limited on the long-term outcomes of GH in patients with molecularly confirmed SRS. This study evaluated height, body mass index (BMI) and GH treatment in molecularly confirmed SRS. DESIGN: An observational study with retrospective data collection. PATIENTS: Individuals with molecularly confirmed SRS aged ≥13 years. MEASUREMENTS: Data were collected on height, height gain (change in height standard deviation score [SDS] from childhood to final or near-final height), BMI and gain in BMI (from childhood to adulthood) and previous GH treatment. RESULTS: Seventy-one individuals (40 female) were included. The median age was 22.0 years (range 13.2-69.7). The molecular diagnoses: H19/IGF2:IG-DMR LOM in 80.3% (57/71); upd(7)mat in 16.9% (12/71) and IGF2 mutation in 2.8% (2/71). GH treatment occurred in 77.5% (55/71). Total height gain was greater in GH-treated individuals (median 1.53 SDS vs. 0.53 SDS, p = .007), who were shorter at treatment initiation (-3.46 SDS vs. -2.91 SDS, p = .04) but reached comparable heights to GH-untreated individuals (-2.22 SDS vs. -2.74 SDS, p = .7). In GH-treated individuals, BMI SDS was lower at the most recent assessment (median -1.10 vs. 1.66, p = .002) with lower BMI gain (2.01 vs. 3.58, p = .006) despite similar early BMI SDS to GH-untreated individuals (median -2.65 vs. -2.78, p = .3). CONCLUSIONS: These results support the use of GH in SRS for increasing height SDS. GH treatment was associated with lower adult BMI which may reflect improved metabolic health even following discontinuation of therapy.
Asunto(s)
Estatura , Índice de Masa Corporal , Hormona de Crecimiento Humana , Síndrome de Silver-Russell , Adolescente , Adulto , Anciano , Femenino , Hormona de Crecimiento Humana/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Síndrome de Silver-Russell/tratamiento farmacológico , Adulto JovenRESUMEN
Beckwith-Wiedemann syndrome (BWS) and Temple syndrome (TS) are classical imprinting disorders (IDs) with nonconfluent clinical features. We report here on a patient with clinical features of both syndromes, in whom epimutations were found at the BWS and TS imprinted regions, consistent with multilocus imprinting disturbance (MLID). This is the first case report of a patient with clinical features of both conditions who was found to have loss of methylation (LOM) of KCNQ1OT1: TSS-DMR (ICR2) in the 11p15 imprinted region associated with BWS and LOM of MEG3: TSS-DMR in the 14q32 imprinted region associated with TS. The report draws attention to the importance of testing for MLID as a cause of atypical clinical presentations of patients with IDs.
Asunto(s)
Síndrome de Beckwith-Wiedemann , Síndrome de Silver-Russell , Síndrome de Beckwith-Wiedemann/diagnóstico , Síndrome de Beckwith-Wiedemann/genética , Metilación de ADN , Impresión Genómica/genética , Humanos , Síndrome de Silver-Russell/diagnóstico , Síndrome de Silver-Russell/genética , Disomía Uniparental/genéticaRESUMEN
BACKGROUND: Silver-Russell syndrome is an imprinting disorder that restricts growth, resulting in short adult stature that may be ameliorated by treatment. Approximately 50% of patients have loss of methylation of the imprinting control region (H19/IGF2:IG-DMR) on 11p15.5 and 5%-10% have maternal uniparental disomy of chromosome 7. Most published research focuses on the childhood phenotype. Our aim was to describe the phenotypic characteristics of older patients with SRS. METHODS: A retrospective cohort of 33 individuals with a confirmed molecular diagnosis of SRS aged 13 years or above were carefully phenotyped. RESULTS: The median age of the cohort was 29.6 years; 60.6% had a height SD score (SDS) ≤-2 SDS despite 70% having received growth hormone treatment. Relative macrocephaly, feeding difficulties and a facial appearance typical of children with SRS were no longer discriminatory diagnostic features. In those aged ≥18 years, impaired glucose tolerance in 25%, hypertension in 33% and hypercholesterolaemia in 52% were noted. While 9/33 accessed special education support, university degrees were completed in 40.0% (>21 years). There was no significant correlation between quality of life and height SDS. 9/25 were parents and none of the 17 offsprings had SRS. CONCLUSION: Historical treatment regimens for SRS were not sufficient for normal adult growth and further research to optimise treatment is justified. Clinical childhood diagnostic scoring systems are not applicable to patients presenting in adulthood and SRS diagnosis requires molecular confirmation. Metabolic ill-health warrants further investigation but SRS is compatible with a normal quality of life including normal fertility in many cases.
Asunto(s)
Factor II del Crecimiento Similar a la Insulina/genética , ARN Largo no Codificante/genética , Síndrome de Silver-Russell/genética , Disomía Uniparental/genética , Adolescente , Adulto , Anciano , Metilación de ADN/genética , Epigénesis Genética , Femenino , Impresión Genómica/genética , Humanos , Masculino , Persona de Mediana Edad , Fenotipo , Calidad de Vida , Síndrome de Silver-Russell/patología , Disomía Uniparental/patología , Adulto JovenRESUMEN
During reproductive age, approximately one in seven couples are confronted with fertility problems. While the aetiology is diverse, including infections, metabolic diseases, hormonal imbalances and iatrogenic effects, it is becoming increasingly clear that genetic factors have a significant contribution. Due to the complex nature of infertility that often hints at a multifactorial cause, the search for potentially causal gene mutations in idiopathic infertile couples has remained difficult. Idiopathic infertility patients with a suspicion of an underlying genetic cause can be expected to have mutations in genes that do not readily affect general health but are only essential in certain processes connected to fertility. In this review, we specifically focus on genes involved in meiosis and maternal-effect processes, which are of critical importance for reproduction and initial embryonic development. We give an overview of genes that have already been linked to infertility in human, as well as good candidates which have been described in other organisms. Finally, we propose a phenotypic range in which we expect an optimal diagnostic yield of a meiotic/maternal-effect gene panel.
Asunto(s)
Predisposición Genética a la Enfermedad , Pruebas Genéticas , Infertilidad/diagnóstico , Infertilidad/genética , Animales , Regulación de la Expresión Génica , Asesoramiento Genético , Marcadores Genéticos , Pruebas Genéticas/métodos , Variación Genética , Humanos , Herencia Materna , Meiosis/genética , Fenotipo , Selección GenéticaRESUMEN
Beckwith-Wiedemann syndrome (BWS) and Silver-Russell syndrome (SRS) are two imprinting disorders associated with opposite molecular alterations in the 11p15.5 imprinting centres. Their clinical diagnosis is confirmed by molecular testing in 50-70% of patients. The authors from different reference centres for BWS and SRS have identified single patients with unexpected and even contradictory molecular findings in respect to the clinical diagnosis. These patients clinically do not fit the characteristic phenotypes of SRS or BWS, but illustrate their clinical heterogeneity. Thus, comprehensive molecular testing is essential for accurate diagnosis and appropriate management, to avoid premature clinical diagnosis and anxiety for the families.
Asunto(s)
Síndrome de Beckwith-Wiedemann/genética , Síndrome de Silver-Russell/genética , Síndrome de Beckwith-Wiedemann/diagnóstico , Cromosomas Humanos Par 11/genética , Metilación de ADN , Predisposición Genética a la Enfermedad/genética , Pruebas Genéticas , Humanos , Fenotipo , Síndrome de Silver-Russell/diagnósticoRESUMEN
BACKGROUND: Genomic imprinting results from the resistance of germline epigenetic marks to reprogramming in the early embryo for a small number of mammalian genes. Genetic, epigenetic or environmental insults that prevent imprints from evading reprogramming may result in imprinting disorders, which impact growth, development, behaviour and metabolism. We aimed to identify genetic defects causing imprinting disorders by whole-exome sequencing in families with one or more members affected by multilocus imprinting disturbance. METHODS: Whole-exome sequencing was performed in 38 pedigrees where probands had multilocus imprinting disturbance, in five of whom maternal variants in NLRP5 have previously been found. RESULTS: We now report 15 further pedigrees in which offspring had disturbance of imprinting, while their mothers had rare, predicted-deleterious variants in maternal effect genes, including NLRP2, NLRP7 and PADI6. As well as clinical features of well-recognised imprinting disorders, some offspring had additional features including developmental delay, behavioural problems and discordant monozygotic twinning, while some mothers had reproductive problems including pregnancy loss. CONCLUSION: The identification of 20 putative maternal effect variants in 38 families affected by multilocus imprinting disorders adds to the evidence that maternal genetic factors affect oocyte fitness and thus offspring development. Testing for maternal-effect genetic variants should be considered in families affected by atypical imprinting disorders.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/genética , Síndrome de Beckwith-Wiedemann/genética , Desiminasas de la Arginina Proteica/genética , Síndrome de Silver-Russell/genética , Proteínas Reguladoras de la Apoptosis , Síndrome de Beckwith-Wiedemann/patología , Cromosomas Humanos Par 11/genética , Metilación de ADN/genética , Femenino , Impresión Genómica/genética , Mutación de Línea Germinal/genética , Humanos , Recién Nacido , Enfermedades del Recién Nacido/genética , Enfermedades del Recién Nacido/fisiopatología , Herencia Materna , Linaje , Embarazo , Arginina Deiminasa Proteína-Tipo 6 , Síndrome de Silver-Russell/fisiopatologíaRESUMEN
The medieval English romance The King of Tars gives an account of a birth of a lump of flesh. This has been considered as fantastic and monstrous in past literature, the horrific union of a Christian and Saracen. However, while the text certainly speaks to miscegenation, we propose that this lump of flesh is actually a hydatidiform mole. We trace the hydatidiform mole from antiquity, surrounding it with contextual medieval examples, from theology, history and medicine, that also describe abnormal births as 'lumps of flesh'. By discussing medieval ideas of monsters as a warning sign, we interpret the lump of flesh in terms of abnormal births, seed transmission, parental contribution and sin. Ideas of warning, blame and intervention present themselves as a response to moles both in medieval texts as well as in modern reactions to hydatidiform moles. We explore the epigenetics of hydatidiform moles and relate them to the medieval text. In The King of Tars, the fault for the lump of flesh could reside with either parent; we find that this is also the case in the genetic formation of the hydatidiform mole; we also argue that the epigenetics supports medieval theories of seed transmission.
Asunto(s)
Mola Hidatiforme/historia , Literatura Medieval , Femenino , Historia Medieval , Humanos , Mola Hidatiforme/genética , EmbarazoRESUMEN
BACKGROUND: Traditional genetic testing focusses on analysis of one or a few genes according to clinical features; this approach is changing as improved sequencing methods enable simultaneous analysis of several genes. Neonatal diabetes is the presenting feature of many discrete clinical phenotypes defined by different genetic causes. Genetic subtype defines treatment, with improved glycaemic control on sulfonylurea treatment for most patients with potassium channel mutations. We investigated the effect of early, comprehensive testing of all known genetic causes of neonatal diabetes. METHODS: In this large, international, cohort study, we studied patients with neonatal diabetes diagnosed with diabetes before 6 months of age who were referred from 79 countries. We identified mutations by comprehensive genetic testing including Sanger sequencing, 6q24 methylation analysis, and targeted next-generation sequencing of all known neonatal diabetes genes. FINDINGS: Between January, 2000, and August, 2013, genetic testing was done in 1020 patients (571 boys, 449 girls). Mutations in the potassium channel genes were the most common cause (n=390) of neonatal diabetes, but were identified less frequently in consanguineous families (12% in consanguineous families vs 46% in non-consanguineous families; p<0·0001). Median duration of diabetes at the time of genetic testing decreased from more than 4 years before 2005 to less than 3 months after 2012. Earlier referral for genetic testing affected the clinical phenotype. In patients with genetically diagnosed Wolcott-Rallison syndrome, 23 (88%) of 26 patients tested within 3 months from diagnosis had isolated diabetes, compared with three (17%) of 18 patients referred later (>4 years; p<0·0001), in whom skeletal and liver involvement was common. Similarly, for patients with genetically diagnosed transient neonatal diabetes, the diabetes had remitted in only ten (10%) of 101 patients tested early (<3 months) compared with 60 (100%) of the 60 later referrals (p<0·0001). INTERPRETATION: Patients are now referred for genetic testing closer to their presentation with neonatal diabetes. Comprehensive testing of all causes identified causal mutations in more than 80% of cases. The genetic result predicts the best diabetes treatment and development of related features. This model represents a new framework for clinical care with genetic diagnosis preceding development of clinical features and guiding clinical management. FUNDING: Wellcome Trust and Diabetes UK.
Asunto(s)
Diabetes Mellitus/genética , Pruebas Genéticas/métodos , Enfermedades del Recién Nacido/genética , Mutación/genética , Diabetes Mellitus/clasificación , Femenino , Humanos , Lactante , Recién Nacido , MasculinoRESUMEN
PURPOSE: Maternal uniparental disomy of chromosome 20 (UPD(20)mat) has been reported in only four patients, three of whom also had mosaicism for complete or partial trisomy of chromosome 20. We sought to evaluate the clinical significance of isolated UPD(20)mat in eight individuals. METHODS: We evaluated phenotypic and genomic findings of a series of eight new patients with UPD(20)mat. RESULTS: All eight individuals with UPD(20)mat had intrauterine growth restriction, short stature, and prominent feeding difficulties with failure to thrive. As a common feature, they often required gastric tube feeds. Genomic data in most patients are indicative of UPD as a result of trisomy rescue after meiosis II nondisjunction. CONCLUSION: We describe the first natural history of the disorder and the results of therapeutic interventions, including the frequent requirement of direct gastric feedings only during the first few years of life, and propose that growth hormone supplementation is probably safe and effective for this condition. We suggest that UPD(20)mat can be regarded as a new imprinting disorder and its identification requires specialized molecular testing, which should be performed in patients with early-onset idiopathic isolated growth failure.Genet Med 18 4, 309-315.
Asunto(s)
Cromosomas Humanos Par 20 , Trastornos del Crecimiento/diagnóstico , Trastornos del Crecimiento/genética , Disomía Uniparental/diagnóstico , Disomía Uniparental/genética , Niño , Preescolar , Facies , Femenino , Impresión Genómica , Genotipo , Trastornos del Crecimiento/tratamiento farmacológico , Hormona de Crecimiento Humana/deficiencia , Hormona de Crecimiento Humana/uso terapéutico , Humanos , Lactante , Masculino , Repeticiones de Microsatélite , Mosaicismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Fenotipo , Polimorfismo de Nucleótido SimpleRESUMEN
We present a Caucasian female, who was diagnosed at 13 years of age with Temple syndrome (formerly referred to as "maternal UPD 14 phenotype") due to an epigenetic loss of methylation at IG-DMR/MEG3-DMR at the chromosome 14q32 imprinted locus. Clinical features were typical and included intra-uterine growth retardation (IUGR), low birth weight, hypotonia, and poor feeding in the neonatal period; and failure to thrive and developmental delay--particularly in relation to speech--in early childhood. Premature puberty, with short stature and truncal obesity, but normal intelligence, were the key features in teenage years. To date only eight patients with Temple syndrome due to an epigenetic error have been described and the etiology of the methylation defect is currently undetermined. In view of a tendency towards central obesity, patients are at potential risk of early-onset type 2 diabetes mellitus, as well as cardiovascular disease and they, therefore, require appropriate monitoring.
Asunto(s)
Cromosomas Humanos Par 14/genética , Metilación de ADN/genética , Impresión Genómica/genética , Péptidos y Proteínas de Señalización Intercelular/genética , Proteínas de la Membrana/genética , ARN Largo no Codificante/genética , Disomía Uniparental/genética , Anomalías Múltiples/genética , Adolescente , Proteínas de Unión al Calcio , Discapacidades del Desarrollo/genética , Femenino , Humanos , Fenotipo , Disomía Uniparental/patologíaRESUMEN
Chromosome 14 harbours an imprinted locus at 14q32. Maternal uniparental disomy of chromosome 14, paternal deletions and loss of methylation at the intergenic differentially methylated region (IG-DMR) result in a human phenotype of low birth weight, hypotonia, early puberty and markedly short adult stature. The analysis of the world literature of 51 cases identifies the key features that will enhance diagnosis and potentially improve treatment. We found a median birth weight SD score (SDS) of -1.88 and median adult final height of -2.04 SDS. Hypotonia and motor delay were reported in 93% and 83% of cases, respectively. Early puberty was reported in 86% of cases with the mean age of menarche at 10â years and 2â months of age. Small hands and feet were reported frequently (87% and 96%, respectively). Premature birth was common (30%) and feeding difficulties frequently reported (n = 22). There was evidence of mildly reduced intellectual ability (measured IQ 75-95). Obesity was reported in 49% of cases, and three patients developed type 2 diabetes mellitus. Two patients were reported to have recurrent hypoglycaemia, and one of these patients was subsequently demonstrated to be growth hormone deficient and started replacement therapy. We propose the use of the name 'Temple syndrome' for this condition and suggest that improved diagnosis and long-term monitoring, especially of growth and cardiovascular risk factors, is required.
Asunto(s)
Trastornos de los Cromosomas , Cromosomas Humanos Par 14/genética , Adolescente , Adulto , Peso al Nacer , Estatura , Índice de Masa Corporal , Peso Corporal , Niño , Preescolar , Trastornos de los Cromosomas/epidemiología , Trastornos de los Cromosomas/genética , Trastornos de los Cromosomas/patología , Estudios de Cohortes , Femenino , Mano/patología , Humanos , Lactante , Masculino , SíndromeRESUMEN
BACKGROUND: Genomic imprinting is allelic restriction of gene expression potential depending on parent of origin, maintained by epigenetic mechanisms including parent of origin-specific DNA methylation. Among approximately 70 known imprinted genes are some causing disorders affecting growth, metabolism and cancer predisposition. Some imprinting disorder patients have hypomethylation of several imprinted loci (HIL) throughout the genome and may have atypically severe clinical features. Here we used array analysis in HIL patients to define patterns of aberrant methylation throughout the genome. DESIGN: We developed a novel informatic pipeline capable of small sample number analysis, and profiled 10 HIL patients with two clinical presentations (Beckwith-Wiedemann syndrome and neonatal diabetes) using the Illumina Infinium Human Methylation450 BeadChip array to identify candidate imprinted regions. We used robust statistical criteria to quantify DNA methylation. RESULTS: We detected hypomethylation at known imprinted loci, and 25 further candidate imprinted regions (nine shared between patient groups) including one in the Down syndrome critical region (WRB) and another previously associated with bipolar disorder (PPIEL). Targeted analysis of three candidate regions (NHP2L1, WRB and PPIEL) showed allelic expression, methylation patterns consistent with allelic maternal methylation and frequent hypomethylation among an additional cohort of HIL patients, including six with Silver-Russell syndrome presentations and one with pseudohypoparathyroidism 1B. CONCLUSIONS: This study identified novel candidate imprinted genes, revealed remarkable epigenetic convergence among clinically divergent patients, and highlights the potential of epigenomic profiling to expand our understanding of the normal methylome and its disruption in human disease.
Asunto(s)
Metilación de ADN/genética , Estudios de Asociación Genética , Genoma Humano/genética , Impresión Genómica/genética , Alelos , Síndrome de Beckwith-Wiedemann/genética , Islas de CpG/genética , Diabetes Mellitus/genética , Regulación de la Expresión Génica , Sitios Genéticos/genética , Humanos , Recién Nacido , Enfermedades del Recién Nacido/genética , Análisis de Secuencia por Matrices de Oligonucleótidos , Reproducibilidad de los Resultados , Ribonucleoproteínas Nucleares Pequeñas/genética , Ribonucleoproteínas Nucleares Pequeñas/metabolismoRESUMEN
BACKGROUND: In a subset of imprinting disorders caused by epimutations, multiple imprinted loci are affected. Familial occurrence of multilocus imprinting disorders is rare. PURPOSE/OBJECTIVE: We have investigated the clinical and molecular features of a familial DNA-methylation disorder. METHODS: Tissues of affected individuals and blood samples of family members were investigated by conventional and molecular karyotyping. Sanger sequencing and RT-PCR of imprinting-associated genes (NLRP2, NLRP7, ZFP57, KHDC3L, DNMT1o), exome sequencing and locus-specific, array-based and genome-wide technologies to determine DNA-methylation were performed. RESULTS: In three offspring of a healthy couple, we observed prenatal onset of severe growth retardation and dysmorphism associated with altered DNA-methylation at paternally and maternally imprinted loci. Array-based analyses in various tissues of the offspring identified the DNA-methylation of 2.1% of the genes in the genome to be recurrently altered. Despite significant enrichment of imprinted genes (OR 9.49), altered DNA-methylation predominately (90.2%) affected genes not known to be imprinted. Sequencing of genes known to cause comparable conditions and exome sequencing in affected individuals and their ancestors did not unambiguously point to a causative gene. CONCLUSIONS: The family presented herein suggests the existence of a familial disorder of DNA-methylation affecting imprinted but also not imprinted gene loci potentially caused by a maternal effect mutation in a hitherto not identified gene.
Asunto(s)
Metilación de ADN/genética , Enfermedades Genéticas Congénitas/genética , Alelos , Análisis Mutacional de ADN , Epigenómica , Femenino , Humanos , Recién Nacido , Masculino , LinajeRESUMEN
BACKGROUND: Transient Neonatal Diabetes Mellitus is the commonest cause of diabetes presenting in the first week of life. Majority of infants recover by 3 months of age but are predisposed to developing type 2 diabetes later on in life. This condition is usually due to genetic aberrations at the 6q24 gene locus, and can be sporadic or inherited. This disorder has three phases: neonatal diabetes, apparent remission, relapse of diabetes. CASE PRESENTATION: Our case, a neonate presented with low birth weight and growth retardation along with the metabolic profile consistent with transient diabetes mellitus at birth. We report a novel clinical observation of recurrent asymptomatic hypoglycaemia detected on pre-feed blood glucose level monitoring in our case with transient neonatal diabetes mellitus at 6 weeks of age, 4 weeks after the remission of diabetes mellitus. CONCLUSION: This case demonstrates that neonates in remission following transient diabetes mellitus can present with recurrent asymptomatic hypoglycaemia without any other obvious congenital malformations seen. This asymptomatic hypoglycaemia may persist for weeks and may be missed if pre-feed blood glucose level monitoring is not done in these infants. Also, these infants may require an aggressive enteral feeding regimen with high glucose delivery rate to maintain normoglycemia.
Asunto(s)
Glucemia/metabolismo , Diabetes Mellitus Tipo 1/sangre , Hipoglucemia/sangre , Recién Nacido de Bajo Peso , Enfermedades del Recién Nacido/sangre , Humanos , Recién Nacido , Insulina/sangre , MasculinoRESUMEN
BACKGROUND: Deregulation of the activity of the ubiquitin ligase E6AP (UBE3A) is well recognised to contribute to the development of Angelman syndrome (AS). The ubiquitin ligase HERC2, encoded by the HERC2 gene is thought to be a key regulator of E6AP. METHODS AND RESULTS: Using a combination of autozygosity mapping and linkage analysis, we studied an autosomal-recessive neurodevelopmental disorder with some phenotypic similarities to AS, found among the Old Order Amish. Our molecular investigation identified a mutation in HERC2 associated with the disease phenotype. We establish that the encoded mutant HERC2 protein has a reduced half-life compared with its wild-type counterpart, which is associated with a significant reduction in HERC2 levels in affected individuals. CONCLUSIONS: Our data implicate a model in which disruption of HERC2 function relates to a reduction in E6AP activity resulting in neurodevelopmental delay, suggesting a previously unrecognised role of HERC2 in the pathogenesis of AS.
Asunto(s)
Amish/genética , Síndrome de Angelman/genética , Factores de Intercambio de Guanina Nucleótido/genética , Mutación , Adolescente , Adulto , Proteínas de Ciclo Celular/química , Línea Celular , Niño , Preescolar , ADN/análisis , ADN/genética , Análisis Mutacional de ADN , Femenino , Fibroblastos/química , Fibroblastos/metabolismo , Estudio de Asociación del Genoma Completo , Factores de Intercambio de Guanina Nucleótido/sangre , Factores de Intercambio de Guanina Nucleótido/química , Factores de Intercambio de Guanina Nucleótido/metabolismo , Células HEK293 , Humanos , Lactante , Masculino , Modelos Moleculares , Proteínas Nucleares/química , Linaje , Ubiquitina-Proteína LigasasRESUMEN
CONTEXT: Low birth weight, as seen in Silver-Russell syndrome (SRS), is associated with later cardiometabolic disease. Data on long-term outcomes and adult body composition in SRS are limited. OBJECTIVE: To evaluate body composition and metabolic health in adults with SRS. METHODS: This was an observational study of 25 individuals with molecularly confirmed SRS, aged ≥â¯18â years, from research facilities across the UK. Body composition and metabolic health were assessed at a single appointment. Individuals with SRS were compared with unaffected men and women (from the Southampton Women's Survey [SWS]). Fat mass, lean mass, bone mineral density (BMD), blood pressure, lipids, and blood glucose were measured. RESULTS: Twenty-five adults with SRS were included (52% female). The median age was 32.9â years (range, 22.0 to 69.7). Fat percentage was greater in the SRS group than the SWS cohort (44.1% vs 30.3%, P < .001). Fat mass index was similar (9.6 vs 7.8, P = .3). Lean mass percentage (51.8% vs 66.2%, P < .001) and lean mass index (13.5â kg/m2 vs 17.3â kg/m2, P < .001) were lower in the SRS group than the SWS cohort. BMD was lower in the SRS group than the SWS cohort (1.08 vs 1.24, P < .001; all median values). Total cholesterol was ≥â¯5â mmol/L in 52.0%. Triglyceride levels were ≥â¯1.7â mmol/L in 20.8%. Fasting blood glucose levels were ≥â¯6.1â mmol/L in 25.0%. Hypertension was present in 33.3%. CONCLUSION: Adults with SRS have an unfavorable body composition and predisposition to cardiometabolic disease. These results support the need for a health surveillance strategy to mitigate adverse outcomes.