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![Identification of KMT2D and KDM6A nonsense mutations responsive to gentamicin treatment. A and B: Comparison between basal and gentamicin-induced readthrough level. Readthrough efficiency for 14 nonsense mutations in the KMT2D gene and for two elsewhere published [Miyake et al., 2013b] nonsense mutations in the KDM6A gene was assessed in HEK293 cells exposed or not to 600–800–1,200 μg/ml of gentamicin for 48 hr. A pCRFL reporter vector harboring the 319d Duchenne muscular dystrophy mutation was used as positive control (CNT). Each value corresponds to the mean of four to six independent experiments. Scale bars represent standard errors. C and D: Gentamicin restored the expression of HOXC6 and S100A4 in patient cultured cells with different efficiency. qPCR analysis was performed to evaluated HOXC6 and S100A4 expression level in two patients LCLs, KB41 (C) and KB45 (D), and two control cell lines treated or not with 800 μg/ml of gentamicin for 48 hr. The results are the mean from at least two experiments performed in duplicate. *P < 0.01.](profile/Giuseppe-Merla/publication/260842615/figure/fig2/AS:267576563466303@1440806632742/Identification-of-KMT2D-and-KDM6A-nonsense-mutations-responsive-to-gentamicin-treatment.png)
Identification of KMT2D and KDM6A nonsense mutations responsive to gentamicin treatment. A and B: Comparison between basal and gentamicin-induced readthrough level. Readthrough efficiency for 14 nonsense mutations in the KMT2D gene and for two elsewhere published [Miyake et al., 2013b] nonsense mutations in the KDM6A gene was assessed in HEK293 cells exposed or not to 600–800–1,200 μg/ml of gentamicin for 48 hr. A pCRFL reporter vector harboring the 319d Duchenne muscular dystrophy mutation was used as positive control (CNT). Each value corresponds to the mean of four to six independent experiments. Scale bars represent standard errors. C and D: Gentamicin restored the expression of HOXC6 and S100A4 in patient cultured cells with different efficiency. qPCR analysis was performed to evaluated HOXC6 and S100A4 expression level in two patients LCLs, KB41 (C) and KB45 (D), and two control cell lines treated or not with 800 μg/ml of gentamicin for 48 hr. The results are the mean from at least two experiments performed in duplicate. *P < 0.01.
Source publication
Kabuki syndrome is a multiple congenital anomalies syndrome characterized by characteristic facial features and varying degrees of mental retardation, caused by mutations in KMT2D/MLL2 and KDM6A/UTX genes. In this study we performed a mutational screening on 303 Kabuki patients by direct sequencing, MLPA, and qPCR identifying 133 KMT2D, 62 never de...
Citations
... A mutation of the histone-demethylase gene, which is crucial to its normal expression, causes an inappropriate methylation of the gene histones which interacts with its correct functioning. 19 While the KDM6A gene seems to be involved in epigenetic modifications during pancreatic differentiation and in insulin secretion, 20,21 the exact mechanism responsible for the insulin hypersecretion in KS is still not known. 22 In the context of HI, a glycemic control will mostly be achieved with diazoxide, a molecule that opens the K + / ATP channels in the beta-cells of the pancreatic islets, leading to hyperpolarization of beta cell and consequently and inhibition of insulin secretion. ...
Key Clinical Message
Kabuki syndrome is a congenital condition characterized by a set of facial dysmorphic features that often help the clinician to suspect the diagnosis. However, more insidious symptoms can rarely occur, such as manifestations of hypoglycemia in newborns with congenital hyperinsulinism hypoglycemia, especially when a variant of the KDM6A gene is found. In those cases, a treatment with diazoxide can be started and can be replaced with lanreotide if a satisfying glycemic control is not achieved. We report the case of a female patient born at 37 weeks of gestational age, without any obvious facial dysmorphic features, after a non‐complicated pregnancy, that presented with feeding difficulties, drowsiness, and irritability revealing a hyperinsulinemic hypoglycemia. Further testing at 6 months old found a KDM6A mutation. The patient was initially treated by diazoxide alone, but its dosage had to be lowered because of the occurrence of treatment side effects, and lanreotide had been added to maintain acceptable blood sugar levels. A congenital hyperinsulinemia hypoglycemia revealed heterozygous truncating variant in the KDM6A gene, also known as X‐linked Kabuki syndrome in a newborn. In cases of neonatal hypoglycemia, the first‐line therapy is diazoxide. Our report shows that analogues of somatostatin such as lanreotide should be considered if the diazoxide regimen is not tolerated.
... Histone methylation can cause either transcriptional activation or suppression depending on which residue is methylated (4). Disruptive variants in lysine methyl transferases (KMTs) and lysine demethylases (KDMs) lead to various neurodevelopmental syndromes that share similar phenotypes including developmental delay (DD), intellectual disability (ID), and craniofacial anomalies (4,(8)(9)(10)(11). Computational analysis (12) and large-scale sequencing studies have highlighted the importance of the lysine methyltransferase gene, KMT5B, in the pathogenesis of neurodevelopmental disorders (11,(13)(14)(15)(16). KMT5B (OMIM: 610881), also denominated suppressor of variegation 4-20 (SUV420H1), is located on chromosome 11q13.2 ...
Pathogenic variants in KMT5B, a lysine methyltransferase, are associated with global developmental delay, macrocephaly, autism, and congenital anomalies (OMIM# 617788). Given the relatively recent discovery of this disorder, it has not been fully characterized. Deep phenotyping of the largest (n = 43) patient cohort to date identified that hypotonia and congenital heart defects are prominent features that were previously not associated with this syndrome. Both missense variants and putative loss-of-function variants resulted in slow growth in patient-derived cell lines. KMT5B homozygous knockout mice were smaller in size than their wild-type littermates but did not have significantly smaller brains, suggesting relative macrocephaly, also noted as a prominent clinical feature. RNA sequencing of patient lymphoblasts and Kmt5b haploinsufficient mouse brains identified differentially expressed pathways associated with nervous system development and function including axon guidance signaling. Overall, we identified additional pathogenic variants and clinical features in KMT5B-related neurodevelopmental disorder and provide insights into the molecular mechanisms of the disorder using multiple model systems.
... Haploinsufficiency of KMT2D and KDM6A is the underlying mechanism associated with KS pathology. Seventy or more percentage of pathogenic variants in KMT2D are either nonsense or frameshift that result in protein truncation and subsequent nonsense-mediated decay (Banka et al., 2015;Makrythanasis et al., 2013;Micale et al., 2014). ...
We aim to assess if genotype-phenotype correlations are present within ocular manifestations of Kabuki syndrome (KS) among a large multicenter cohort. We conducted a retrospective, medical record review including clinical history and comprehensive ophthalmological examinations of a total of 47 individuals with molecularly confirmed KS and ocular manifestations at Boston Children's Hospital and Cincinnati Children's Hospital Medical Center. We assessed information regarding ocular structural, functional, and adnexal elements as well as pertinent associated phenotypic features associated with KS. For both type 1 KS (KS1) and type 2 KS (KS2), we observed more severe eye pathology in nonsense variants towards the C-terminus of each gene, KMT2D and KDM6A, respectively. Furthermore, frameshift variants appeared to be not associated with structural ocular elements. Between both types of KS, ocular structural elements were more frequently identified in KS1 compared with KS2, which only involved the optic disc in our cohort. These results reinforce the need for a comprehensive ophthalmologic exam upon diagnosis of KS and regular follow-up exams. The specific genotype may allow risk stratification of the severity of the ophthalmologic manifestation. However, additional studies involving larger cohorts are needed to replicate our observations and conduct powered analyses to more formally risk-stratify based on genotype, highlighting the importance of multicenter collaborations in rare disease research.
... with X-linked dominant inheritance affecting 5%-8% of the patients [1,3,7]. Both genes have an interconnected epigenetic regulatory function in histone methylation, involving chromatin remodeling, and are essential regulators of muscle-specific genes during embryogenesis [3,8]. ...
... Dental-oral anomalies are common in KS patients, affecting 60% to 86% of them (Table 1) [5,6,13,[16][17][18][19][20]. The maxillary lateral and mandibular central incisors are the most commonly missing teeth in KS patients and probably more common in KS patients with a heterozygous pathogenic variant of the KMT2D gene [5,6,8,17,19,20]. Oligodontia, hypodontia, screwdriver-shaped incisors, ectopic permanent first molars, cleft palate, and lip pits are considered supportive features in the clinical diagnosis of KS [5]. ...
Kabuki syndrome (KS) is an epigenetic machinery multisystem disorder with peculiar facial gestalt and dental-oral anomalies. This report describes the case of a KS patient with congenital hyperinsulinism, growth hormone deficiency and novel heterogenous missense mutations in exon 25 of the KDM6A (c.3715T>G, p.Trp1239Gly) and exon 1 of the ABCC8 (c.94A>G, p.Asn32Asp) genes. She presented with solitary median maxillary central incisor (SMMCI) and mandibular incisor hypodontia, which could be a unique dental manifestation in KS 2. Keywords Hypodontia; Kabuki syndrome 2; KDM6A; Solitary central incisor
... To investigate the pathogenesis of KS, mouse models have been generated and their cells have been used as convenient materials for analyzing cellular phenotypes in KS [8-11, 16, 17]. Lymphoblastoid and skin fibroblast cell lines from patients with KS have also been used to identify important dysregulated genes that could explain some of the human phenotypes [13,18]. Histone code analysis is essential to reveal the pathogenesis of KS, but some analyses, including acetylation/ methylation and topologically associating domains, are difficult especially with patient material. ...
Background:
Kabuki syndrome (KS) is a congenital malformation syndrome caused by mutations in the KMT2D and KDM6A genes that encode histone modification enzymes. Although KS is considered a single gene disorder, its symptoms vary widely. Recently, disease-specific DNA methylation patterns, or episignatures, have been recognized and used as a diagnostic tool for KS. Because of various crosstalk mechanisms between histone modifications and DNA methylation, DNA methylation analysis may have high potential for investigations into the pathogenesis of KS.
Results:
In this study, we investigated altered CpG-methylation sites that were specific to KS to find important genes associated with the various phenotypes or pathogenesis of KS. Whole genome bisulfite sequencing (WGBS) was performed to select target CpG islands, and enzymatic conversion technology was applied after hybridization capture to confirm KS-specific episignatures of 130 selected differently methylated target regions (DMTRs) in DNA samples from the 65 participants, 31 patients with KS and 34 unaffected individuals, in this study. We identified 26 candidate genes in 22 DMTRs that may be associated with KS. Our results indicate that disease-specific methylation sites can be identified from a small number of WGBS samples, and hybridization capture followed by enzymatic methylation sequencing can simultaneously test the sites.
Conclusions:
Although DNA methylation can be tissue-specific, our results suggest that methylation profiling of DNA extracted from peripheral blood may be a powerful approach to study the pathogenesis of diseases.
... Each replicate signal was normalized to its own input samples. (29), so this idea needs to be further explored in future studies. ...
Kabuki syndrome (KS) is frequently caused by loss-of-function mutations in one allele of the H3K4 methyltransferase KMT2D and is associated with problems in neurological, immunological, and skeletal system development. We generated heterozygous KMT2D knock-out and Kabuki-patient derived cell models to investigate the role of KMT2D reduced dosage in stem cells. We discovered chromosomal locus-specific alterations in gene expression, specifically a 110Kb region containing SYT3, CLEC11A, C19ORF81, and SHANK1, suggesting locus-specific targeting of KMT2D. Using whole genome histone methylation mapping, we confirmed locus-specific changes in H3K4 methylation patterning co-incident with regional decreases in gene expression in Kabuki cell models. Significantly reduced H3K4 peaks aligned with regions of stem cell maps of H3K27 and H3K4 methylation, suggesting KMT2D haploinsufficiency impacts bivalent enhancers in stem cells. Preparing the genome for subsequent differentiation cues may be of significant importance for Kabuki-related genes. This work provides new insight into the mechanism of action of an important gene in bone and brain development and may increase our understanding of a specific function of a human disease-relevant H3K4 methyltransferase family member.
... The majority of KS cases are caused by pathogenic mutations in either KMT2D or KDM6A, 2 genes that encode proteins used for chromatin transcription. Pathogenic mutations in these genes impair normal histone methylation resulting in abnormalities across multiple organ systems, likely due to alterations in gene expression regulated by imprinting control regions such as the 11p15 locus associated with Beckwith-Wiedemann syndrome and adjacent to KATP genes [2,7]. Mutations in the KMT2D gene are autosomal dominant and are responsible for more than 75% of KS. ...
Kabuki syndrome (KS) is a multisystem disorder estimated to occur in 1:32,000 newborns. Pathogenic mutations cause the majority but not all cases of KS in either KMT2D or KDM6A . KS can be suspected by phenotypic features, including infantile hypotonia, developmental delay, dysmorphic features, congenital heart defects, and others. Still, many of these features are not readily apparent in a newborn. Although neonatal hypoglycemia has been reported in eight to ten percent of patients with KS, the incidence and severity of hyperinsulinemic hypoglycemia (HH) is not well-studied.
We present a full-term female infant with HH who was responsive to low-dose Diazoxide. At three months of age, she was admitted for septic shock, worsening respiratory status and severe pulmonary hypertension, requiring extracorporeal membrane oxygenation (ECMO) support. Her neonatal history was notable for hypotonia, dysphagia with aspiration requiring gastrostomy tube placement, and a cardiac defect - hypoplastic aortic arch requiring aortic arch repair. She has characteristic facial features, including prominent eyelashes, long palpebral fissures, and a short nasal columella. Next-Generation Sequencing (NGS) for HH revealed a de novo likely pathogenic missense variant in KDM6A gene: c.3479G>T, p.Gly1160Val that was absent from population databases.
Genetic testing for causes of HH should include testing of the KS genes KMT2D and KDM6A. Early detection of the underlying genetic defect will help guide management as all reported HH cases associated with KS have been responsive to Diazoxide. Affected infants with underlying cardiac conditions may be at higher risk of serious respiratory complications such as pulmonary hypertension.
... Raw C t values were obtained using SDS 2.3 (Applied Biosystem, Vilnius, Lithuania). Calculations were carried out by the comparative C t method as reported in Micale et al. (2014). Significance was determined by an unpaired, two-sample t tests. ...
Cooks syndrome (CS) is an ultrarare limb malformation due to in tandem microduplications involving KCNJ2 and extending to the 5′ regulatory element of SOX9. To date, six CS families were resolved at the molecular level. Subsequent studies explored the evolutionary and pathological complexities of the SOX9-KCNJ2/Sox9-Kcnj2 locus, and suggested a key role for the formation of novel topologically associating domain (TAD) by inter-TAD duplications in causing CS. Here, we report a unique case of CS associated with a de novo 1;17 translocation affecting the KCNJ2 locus. On chromosome 17, the breakpoint mapped between KCNJ16 and KCNJ2, and combined with a ~ 5 kb deletion in the 5′ of KCNJ2. Based on available capture Hi-C data, the breakpoint on chromosome 17 separated KCNJ2 from a putative enhancer. Gene expression analysis demonstrated downregulation of KCNJ2 in both patient’s blood cells and cultured skin fibroblasts. Our findings suggest that a complex rearrangement falling in the 5′ of KCNJ2 may mimic the developmental consequences of in tandem duplications affecting the SOX9-KCNJ2/Sox9-Kcnj2 locus. This finding adds weight to the notion of an intricate role of gene regulatory regions and, presumably, the related three-dimensional chromatin structure in normal and abnormal human morphology.
... Изза иммунодефицита пациенты склонны к частым инфекционным заболеваниям (особенно часто встречаются инфекции верхних дыхательных путей, пневмонии). Возможно развитие идиопатической тромбоцитопенической пурпуры, аутоиммунной гемолитической анемии (9 %), полицитемии (4 %), гипогаммаглобулинемии А, неонатальной гипербилирубинемии (20 %) и муковисцидоза (2 %) [16]. ...
Kabuki syndrome (KS) is a rare genetic disorder that has facial phenotypic descriptors, retarded growth, various malformations and different degrees of intellectual disability.Objective: to study the characteristic features of KS comorbid with West syndrome according to literature review and data collection together with KS described clinically, and treatment success rates by the clinical case study research.There was conducting literature review on the topic in the databases OMIM, PubMed, Scopus, and e-library. The articles describing cases of epilepsy in patients with KS were analyzed. We conducted our own observation of KS in the male patient with epilepsy and West syndrome in a patient with KS was analyzed by the clinical case study research.Kabuki syndrome comorbid with West syndrome increases neurological deficits and leads to the formation of a marked delay in mental and speech development and psychomotor development retardation. Peculiarities of the treatment of KS comorbid with West syndrome are the lack of efficacy of antiepileptic drugs, and the very visible effectiveness of the ketogenic diet, together with an atypical response to hormone replacement therapy in the form of distinct positive dynamics – a clinically meaningful reduction in seizure frequency along with elevated liver enzymes.
... Urogenital abnormalities are reported in 30-40% of KS patients [24] and include hydronephrosis, abnormal kidney position, renal hypoplasia or dysplasia, and fusion defects [16]. These anomalies showed a high frequency (60%) in our patients. ...
... More than 50% of KS patients reported in the literature are overweight or obese, during childhood or adolescence [16,Fig. 3 Facial fetaures in some of KS patients reported in this paper; the code is the same reported in Tables S1-S2. ...
... Regarding genotype-phenotype correlation, it has been reported that patients with KMT2D variants show a significantly higher frequency of short stature, typical facial features, persistent fetal finger pads, renal abnormalities, and feeding problems compared with patients with KDM6A variants [7,10,16,[67][68][69][70]; conversely, KDM6A variants are associated with variable phenotypes, ranging from typical KS to milder clinical presentations [11][12][13][14][15]. Patients with KDM6A variants seem to have hypotonia and feeding difficulties during infancy, poor postnatal growth, and short stature. ...
Kabuki syndrome (KS) is a well-recognized disorder characterized by postnatal growth deficiency, dysmorphic facial features, skeletal anomalies, and intellectual disability. The syndrome is caused by KMT2D gene mutations or less frequently KDM6A gene mutations or deletions. We report a systematic evaluation of KS patients from Campania region of Italy; data were also compared with literature ones. We collected data of 15 subjects (8 males and 7 females with age range 10–26 years; mean age 16.9 years) with confirmed diagnosis of KS, representing the entire cohort of patients from Campania Region. Each patient performed biochemical testing and instrumental investigation. Neuro-intellectual development, cranio-facial dysmorphisms, and multisystem involvement data were collected retrospectively. For each category, type of defects and frequency of the anomalies were analyzed. Our observation shows that KS patients from Campania region have some particular and previously underscored, neurological and immunological findings. We found high prevalence of EEG’s abnormalities (43%) and MRI brain abnormalities (60%). Microcephaly resulted more common in our series (33%), if compared with major cohorts described in literature. Biochemical features of immunodeficiency and autoimmune diseases including thyroid autoimmunity, polyserositis, and vitiligo were observed with high prevalence (54.5%). Low immunoglobulins levels were a frequent finding. Lymphocyte class investigation showed significantly reduced CD8 levels in one patient.
Conclusions : These data confirm great heterogeneity of clinical manifestations in KS and suggest to introduce further clinical diagnostic criteria in order to perform a correct and precocious diagnosis. What is Known • Kabuki syndrome is characterized by growth deficiency, dysmorphic facial features, skeletal anomalies, and intellectual disability • Immune dysfunction is a common finding but autoimmune diseases are rarely seen • Neurological features are common
What is New • Some particular facial features could help gestalt diagnosis (hypertelorism, broad nasal bridge, micrognathia, tooth agenesis, cutaneous haemangiomas and strabismus) • Higher prevalence of autoimmune disorders than previously reported • Particular neurological features are present in this cohort (EEG and MRI brain abnormalities)
