Insights into the genotype-phenotype relationship of ocular manifestations in Kabuki syndrome

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.

From Genotype to Phenotype-A Review of Kabuki Syndrome

Kabuki syndrome (KS) is a rare neuro-developmental disorder caused by variants in genes of histone modification, including KMT2D and KDM6A. This review assesses our current understanding of KS, which was originally named Niikawa-Kuroki syndrome, and aims to guide surveillance and medical care of affected individuals as well as identify gaps in knowledge and unmet patient needs. Ovid MEDLINE and EMBASE databases were searched from 1981 to 2021 to identify reports related to genotype and systems-based phenotype characterization of KS. A total of 2418 articles were retrieved, and 152 were included in this review, representing a total of 1369 individuals with KS. Genotype, phenotype, and the developmental and behavioral profile of KS are reviewed. There is a continuous clinical phenotype spectrum associated with KS with notable variability between affected individuals and an emerging genotype-phenotype correlation. The observed clinical variability may be attributable to differences in genotypes and/or unknown genetic and epigenetic factors. Clinical management is symptom oriented, fragmented, and lacks established clinical care standards. Additional research should focus on enhancing understanding of the burden of illness, the impact on quality of life, the adult phenotype, life expectancy and development of standard-of-care guidelines.

Mechanism for DPY30 and ASH2L intrinsically disordered regions to modulate the MLL/SET1 activity on chromatin

Recent cryo-EM structures show the highly dynamic nature of the MLL1-NCP (nucleosome core particle) interaction. Functional implication and regulation of such dynamics remain unclear. Here we show that DPY30 and the intrinsically disordered regions (IDRs) of ASH2L work together in restricting the rotational dynamics of the MLL1 complex on the NCP. We show that DPY30 binding to ASH2L leads to stabilization and integration of ASH2L IDRs into the MLL1 complex and establishes new ASH2L-NCP contacts. The significance of ASH2L-DPY30 interactions is demonstrated by requirement of both ASH2L IDRs and DPY30 for dramatic increase of processivity and activity of the MLL1 complex. This DPY30 and ASH2L-IDR dependent regulation is NCP-specific and applies to all members of the MLL/SET1 family of enzymes. We further show that DPY30 is causal for de novo establishment of H3K4me3 in ESCs. Our study provides a paradigm of how H3K4me3 is regulated on chromatin and how H3K4me3 heterogeneity can be modulated by ASH2L IDR interacting proteins.

Regulation of the MLL family of histone H3K4 methyltransferases on the nucleosome core particle (NCP) remains largely unknown. Here the authors show that intrinsically disordered regions of ASH2L and DPY30 restrict the rotational dynamics of MLL1 on the NCP, allowing more efficient enzyme-substrate engagement and higher H3K4 trimethylation activity.

Ophthalmic manifestations in Kabuki (make-up) syndrome: A single-center pediatric cohort and systematic review of the literature

Kabuki syndrome (KS) is a genetic disorder caused by pathogenic variants in KMT2D or KDM6A, and manifesting with multi-systemic involvement, including recognizable facial features, developmental delay and multiple congenital anomalies. Ophthalmological involvement has been described in varying rates in several studies. We aimed to evaluate the prevalence and nature of ophthalmological findings in a cohort of KS patients in Israel. Medical records of all patients diagnosed with KS in our tertiary center between 2004 and 2020 were retrospectively reviewed. Data collected included physical examination findings, molecular analysis as well as comprehensive ophthalmic characteristics including visual acuity, ocular alignment and motility, ocular adnexa, anterior segments and dilated fundus exams. Finally, an updated systematic review of the literature was performed. Thirteen unrelated patients were included in the study, diagnosed at an age raging from the first months of life to 20 years. Of these, three (23%) showed significant ophthalmological abnormalities, beyond the characteristic structural findings of long palpebral fissures and lower eyelid eversion. These included bilateral posterior colobomata in the first patient; bilateral ptosis, hypermetropia, esotropia, blue sclera and anisocoria in the second; and bilateral congenital cataracts in the third. To conclude, our findings underscore the importance of a comprehensive ophthalmological evaluation as part of the routine multidisciplinary assessment of children suspected/diagnosed with KS.

Using Xenopus to analyze neurocristopathies like Kabuki syndrome

Neurocristopathies are human congenital syndromes that arise from defects in neural crest (NC) development and are typically associated with malformations of the craniofacial skeleton. Genetic analyses have been very successful in identifying pathogenic mutations, however, model organisms are required to characterize how these mutations affect embryonic development thereby leading to complex clinical conditions. The African clawed frog Xenopus laevis provides a broad range of in vivo and in vitro tools allowing for a detailed characterization of NC development. Due to the conserved nature of craniofacial morphogenesis in vertebrates, Xenopus is an efficient and versatile system to dissect the morphological and cellular phenotypes as well as the signaling events leading to NC defects. Here, we review a set of techniques and resources how Xenopus can be used as a disease model to investigate the pathogenesis of Kabuki syndrome and neurocristopathies in a wider sense.

Ocular manifestations in kabuki syndrome: A report of 10 cases and literature review

Background: We investigated the ocular manifestations in patients with Kabuki syndrome(KS).Methods: A retrospective chart review was performed in 10 patients with KS were referred to the Department of Ophthalmology for evaluation of ocular manifestations. Data were collected from patient interviews, clinical examinations, and laboratory investigations. Ophthalmologic examinations included best-corrected visual acuity, intraocular pressure, anterior segment, adnexal examination, and dilated fundus examination.Results: Mutations in the KMT2D gene were identified in all of the 10 patients with KS. No deletion or point mutation was found in the KDM6A gene. In our patients, 20% had ptosis, 60% had strabismus, 90% had lid changes and 10% had amblyopia. Five patients did not undergo the visual acuity test due to intellectual disability.Conclusions: Ophthalmic abnormalities are frequently associated with KS. The importance of ophthalmological examination in all patients with KS for early detection of ocular anomalies to prevent visual impairment cannot be underemphasized.Abbreviations: KS: Kabuki syndrome.

Congenital Refractory Glaucoma: A New Ophthalmic Association of Kabuki Syndrome and its Management With Glaucoma Drainage Devices

INTRODUCTION

Kabuki syndrome (KS) is a rare congenital and polymalformative condition, traditionally associated with mental retardation, unusual facial features, and skeletal abnormalities. We hereby describe a case of bilateral congenital glaucoma associated with MLL2-mutation KS. To the best of our knowledge, this is the first association of KS with congenital glaucoma.

CASE REPORT

The patient was a 3-year-old male of North African ethnicity diagnosed with KS and bilateral congenital glaucoma at the age of 3 months and the first child of a nonconsanguineous healthy couple, with no known genetic conditions within the family. The patient was referred to our tertiary glaucoma center with uncontrollable intraocular pressures between 50 and 60 mm Hg in both eyes. Past ophthalmic history included bilateral trabeculectomies and right retinal detachment with phthisis bulbi. We performed left lensectomy combined with Baerveldt tube insertion in the vitreous cavity, revealing extensive posterior synechiae. Postoperatively, he developed intense inflammation with fibrin and vitreous strand formation, requiring subsequent surgeries and subconjunctival injections of betamethasone. Despite these complications, IOP stabilized between 3 and 6 mm Hg.

DISCUSSION

This case confirms congenital glaucoma as a rare association of KS, and highlights the potential high-risk nature of such cases. In our opinion, the presence of high levels of inflammation perioperatively and postoperatively is an indication for primary glaucoma drainage device surgery given the high risk of bleb scarring resulting in recurrent surgical revisions. In view of these observations, we also advocate the use of intensive postoperative anti-inflammatory therapy.

Changes in ocular motility in Kabuki syndrome

Kabuki syndrome is a rare genetic disorder, caused by mutation in the KMT2D or KDM6A genes, which affects several organs in the majority of patients, among which are the eyes. The most typical clinical characteristics are mental retardation, postnatal growth retardation, skeletal anomalies, and characteristic facial features. As the eyes are affected in most of the cases, ophthalmological examination is recommended for the early detection of ocular anomalies, in order to prevent visual impairment. The most frequent ocular signs are strabismus, ptosis, and refractive anomalies. A series of cases of Kabuki syndrome is described in five children, four of whom exhibited strabismus with esotropia, over action of inferior oblique muscles, and under action of superior oblique muscles associated with a V pattern. Most published papers do not report or might underestimate the ocular problems. It may be appropriate to perform orbital magnetic resonances in order to detect changes in the muscle paths that are related to the pathology of the eye movements found.

Salzmann nodular degeneration features in a case of Kabuki make-up syndrome

Kabuki syndrome (KS) is a multiple congenital anomaly syndrome with diversified ophthalmological manifestations. We report a case of a boy with bilateral features of Salzmann nodular degeneration (SND) associated with KS. An 18-year-old Caucasian man with KS presented for a second opinion regarding incapacitating photophobia in his right eye, refractory to medical therapy. Biomicroscopy revealed bilateral subepithelial nodules in the midperiphery of the cornea, less extensive in the left eye, consistent with SND. Symptomatic improvement was achieved after superficial keratectomy, manually performed with a blade and adjuvant application of mitomycin C. We report a rare case of a KS patient with SND. Since KS manifestations may vary widely, it is important to perform an early ophthalmological examination for prompt detection and treatment of ocular abnormalities and thus improve life quality in these patients.

Kabuki syndrome: expanding the phenotype to include microphthalmia and anophthalmia

Kabuki syndrome is a rare genetic malformation syndrome that is characterized by distinct facies, structural defects and intellectual disability. Kabuki syndrome may be caused by mutations in one of two histone methyltransferase genes: KMT2D and KDM6A. We describe a male child of nonconsanguineous Irish parents presenting with multiple malformations, including bilateral extreme microphthalmia; cleft palate; congenital diaphragmatic hernia; duplex kidney; as well as facial features of Kabuki syndrome, including interrupted eyebrows and lower lid ectropion. A de-novo germline mutation in KMT2D was identified. Whole-exome sequencing failed to reveal mutations in any of the known microphthalmia/anopthalmia genes. We also identified four other patients with Kabuki syndrome and microphthalmia. We postulate that Kabuki syndrome may produce this type of ocular phenotype as a result of extensive interaction between KMT2D, WAR complex proteins and PAXIP1. Children presenting with microphthalmia/anophthalmia should be examined closely for other signs of Kabuki syndrome, especially at an age where the facial gestalt might be less readily appreciable.

Mutation of the melastatin-related cation channel, TRPM3, underlies inherited cataract and glaucoma

Inherited forms of cataract are a clinically important and genetically heterogeneous cause of visual impairment that usually present at an early age with or without systemic and/or other ocular abnormalities. Here we have identified a new locus for inherited cataract and high-tension glaucoma with variable anterior segment defects, and characterized an underlying mutation in the gene coding for transient receptor potential cation channel, subfamily M, member-3 (TRPM3, melastatin-2). Genome-wide linkage analysis mapped the ocular disease locus to the pericentric region of human chromosome 9. Whole exome and custom-target next-generation sequencing detected a heterozygous A-to-G transition in exon-3 of TRPM3 that co-segregated with disease. As a consequence of alternative splicing this missense mutation was predicted to result in the substitution of isoleucine-to-methionine at codon 65 (c.195A>G; p.I65 M) of TRPM3 transcript variant 9, and at codon 8 (c.24A>G; p.I8 M) of a novel TRPM3 transcript variant expressed in human lens. In both transcript variants the I-to-M substitution was predicted in silico to exert damaging effects on protein function. Furthermore, transient expression studies of a recombinant TRPM3-GFP reporter product predicted that the I-to-M substitution introduced an alternative translation start-site located 89 codons upstream from the native initiator methionine found in eight other TRPM3 transcript variants (1-8). Collectively, these studies have provided the first evidence that TRPM3 is associated with inherited ocular disease in humans, and further provide support for the important role of this cation channel in normal eye development.

Strabismus and poor stereoacuity associated with Kabuki syndrome

Kabuki syndrome is characterized by long palpebral fissures, large ears, a depressed nasal tip, and skeletal anomalies associated with postnatal dwarfism and mental retardation. There have been few prior detailed descriptions of strabismus or stereopsis in these patients. We report a patient with Kabuki syndrome who showed small-angle strabismus and poor stereopsis. This case illustrates the need for patients with a diagnosis of Kabuki syndrome to have an ophthalmologic evaluation. Strabismus associated with Kabuki syndrome may have a small angle that can be easily overlooked.

Ocular manifestations in Kabuki syndrome: the first report from Saudi Arabia

BACKGROUND

Kabuki syndrome (KS) is a multiple congenital anomaly syndrome in which ophthalmological examination for the early detection of ocular abnormalities is desired in order to prevent visual impairment.

CASE

Retrospective, interventional, case report of a 5-year-old female patient of Arabic origin with features of Kabuki syndrome.

OBSERVATION

Patient had neurological deficit, psychomotor retardation, a peculiar face, including large prominent cup shaped ears, broad depressed nasal tip, and high arched palate, and malformed teeth. Her ocular features suggestive of Kabuki syndrome included left upper eyelid congenital ptosis, lagophthalmos, arched eyebrows with temporal sparing of hair, long horizontal palpebral fissures, lateral lower eyelid eversion and resultant epiphora. Other abnormalities included medial lower epicanthal folds, abduction deficit bilaterally, large esotropia, significant hyperopia, right corneal opacity, iris and chorioretinal coloboma. Patient required hyperopic correction and ptosis surgery, which improved her visual functioning.

CONCLUSIONS

We report the first case of a Kabuki syndrome patient from Saudi Arabia and stress on the importance of ophthalmological examination in all patients with KS for the early detection of ocular anomalies in order to prevent visual impairment.

Kabuki syndrome: a review

Kabuki syndrome (KS) (Kabuki make-up syndrome, Niikawa-Kuroki syndrome) is a multiple malformation/mental retardation syndrome that was described initially in Japan but is now known to occur in many other ethnic groups. It is characterized by distinctive facial features (eversion of the lower lateral eyelid, arched eyebrows with the lateral one-third dispersed or sparse, depressed nasal tip, and prominent ears), skeletal anomalies, dermatoglyphic abnormalities, short stature, and mental retardation. A number of other manifestations involving other organ systems can aid in the diagnosis and management of KS. This review will focus on the diagnostic criteria, the common and rare features of KS by organ system, and the possible etiology of this interesting condition.

Kabuki syndrome: new ocular findings but no evidence of 8p22-p23.1 duplications in a clinically defined cohort

The underlying cause of the multiple congenital anomalies/mental retardation syndrome Kabuki syndrome (KS, OMIM 147920) has not yet been established. We identified seven patients who fulfilled the classical clinical criteria for this syndrome and undertook a detailed clinical, ophthalomological and molecular cytogenetic review. Three of the seven patients had previously undetected ocular anomalies including myopia, ptosis, strabismus and tilted discs. The identification of preventable causes of loss of vision underlines the value of detailed ophthalmologic examination of KS patients. Using BAC fluorescence in situ hybridisation, there was no evidence of the duplication of 8p recently reported by Milunsky and Huang. We conclude that the cause of KS has yet to be established.

Failure to detect an 8p22–8p23.1 duplication in patients with Kabuki (Niikawa–Kuroki) syndrome

Kabuki syndrome (KS) is a rare MCA/MR syndrome with an estimated frequency of 1/32 000 in Japan. This syndrome is characterized by postnatal growth retardation, distinctive facial features, dermatoglyphic anomalies, skeletal dysplasia, and mental retardation. The molecular basis of KS remains unknown. Recently, Milunsky and Huang reported on six unrelated patients with a clinical diagnosis of KS and an 8p22-8p23.1 duplication using comparative genomic hybridization and BAC-FISH studies. Also, they suggested that a paracentric inversion may contribute to the occurrence of KS. In the present study, 24 patients with a clinical diagnosis of KS based on Niikawa-Kuroki criteria have been collected. They were tested for the presence of an 8p duplication using the same clones as described by Milunsky and Huang. Our results do not confirm the previously described association between KS and an 8p22-8p23.1 duplication.

Atypical findings in Kabuki syndrome: report of 8 patients in a series of 20 and review of the literature

Kabuki syndrome (KS) is a rare multiple congenital anomaly/mental retardation syndrome with an estimated frequency of 1/32,000 in Japan. Five major criteria delineate KS namely postnatal short stature, skeletal anomalies, moderate mental retardation, dermatoglyphic anomalies, and a characteristic facial dysmorphism. Here we report on a series of 20 sporadic KS patients and we focus on some rare and atypical features that we have observed: chronic and/or severe diarrhea (4/20) including celiac disease, diaphragmatic defects (3/20), pseudarthrosis of the clavicles (2/20), vitiligo (2/20), and persistent hypoglycemia (2/20). Other occasional findings were severe autoimmune thrombopenia, cerebellar vermis atrophy, and myopathic features. Interestingly, one of our KS patients presented with a clinical overlap with CHARGE syndrome (right eye microphtalmia with optic nerve coloboma, VSD, bilateral cryptorchidism, and severe deafness). Because these features are more frequent in our series than previously described, we propose to carefully investigate these manifestations during KS patient survey in an attempt to determine their real frequency and in order to improve clinical management.

Kabuki syndrome: Clinical data in 20 patients, literature review, and further guidelines for preventive management

The Kabuki syndrome, or Niikawa-Kuroki syndrome, is a clinically recognizable syndrome of unknown etiology. Clinical findings include early hypotonia, joint laxity, developmental delay, facial dysmorphism, persistent fetal fingertip pads, cleft palate, hypodontia, lip nodules, heart defects, and a variety of other structural defects. Behavior in general is social and pleasant. In collaboration with the Dutch Kabuki Network, we evaluated the medical data of 20 individuals diagnosed with the syndrome and compared them with data from the literature. In our literature review we used convincing cases only. Frequent findings in the oral region are under-reported in the literature: apart from the cleft palate (in about 50%), hypodontia with predominantly absence of the upper lateral incisors, and a full lower lip with symmetrical nodules, or (in a minority) lip-pits are frequent findings. Also under-reported is the presence of a thickened nuchal fold during pregnancy and hydrops in the neonatal period. Clinical recognition in the neonate is difficult. Towards early puberty acute and serious weight excess has been experienced. We suggest that a cytogenetic abnormality should be ruled out in all cases. We provide further guidelines for preventive management.

Coloboma and other ophthalmologic anomalies in Kabuki syndrome: distinction from charge association

Kabuki (Niikawa-Kuroki) syndrome is associated with growth retardation, developmental delay, congenital heart disease, cleft palate, and characteristic facial features. Although the external appearance of the eyes has been well-described, the type and frequency of structural and functional eye anomalies has not been emphasized. We report three children with Kabuki syndrome who also had a retinal coloboma. A diagnosis of CHARGE association was initially suggested in two of the patients before the typical facial features of Kabuki syndrome emerged. A detailed review of reported cases of Kabuki syndrome shows that a variety of eye anomalies are associated with Kabuki syndrome. The incidence of coloboma is greatly increased in Kabuki syndrome. Thus, ophthalmologic abnormalities are frequently associated with Kabuki syndrome, and an ophthalmologic evaluation should be performed for each patient. Phenotypic overlap, including congenital heart, ear, and renal defects, can lead to the diagnosis of CHARGE association, especially since the typical facial features of Kabuki syndrome may not be apparent in early infancy. Thus, Kabuki syndrome should be considered in patients with coloboma if other features consistent with this condition are present, and follow-up evaluations are indicated for establishing the proper diagnosis.

Kabuki make-up syndrome: a review

Kabuki make-up syndrome (KMS, OMIM 147920) is an MCA/MR syndrome of unknown cause. It is characterized by a dysmorphic face, postnatal growth retardation, skeletal abnormalities, mental retardation, and unusual dermatoglyphic patterns. Approximately more than 350 cases have been reported from all over the world. Besides these five cardinal manifestations, joint laxity (74%), dental abnormalities (68%), and susceptibility to infections including recurrent otitis media (63%) were well recognized as other frequent features. A variety of visceral anomalies such as cardiovascular anomalies (42%), renal and/or urinary tract anomalies (28%), biliary atresia, diaphragmatic hernia, and anorectal anomaly were also reported. Some patients were said to have normal intelligence (16%) and normal heights, suggesting that they may have reproductive fitness to have their children. At least eight patients had lower lip pits with or without cleft palate, known as a feature of van der Woude syndrome. There have been 13 chromosomal abnormalities associated with KMS. However, no common abnormalities or breakpoints that possibly contribute to positional cloning of the putative KMS gene(s) are known. Although clinical manifestations of KMS are well established, its natural history, useful for genetic counseling, remains to be studied.

Kabuki syndrome: a review study of three hundred patients

The Kabuki (make-up) syndrome identified in 1981 has been reported in more than three hundred patients. Typical findings include mild to moderate mental retardation, fetal pads, cleft palate, and characteristic facies with long palpebral fissures, everted lower lateral eyelids and arched eyebrows. Postnatal growth retardation, skeletal and visceral anomalies are present in a large percentage of patients. We review here the characteristics of this peculiar syndrome in three hundred patients.

Clinical phenotypes of nine cases of Kabuki syndrome from New Zealand

Nine cases of Kabuki syndrome have been identified in Auckland and surrounding regions in the North Island, New Zealand since 1995. All have the characteristic facial dysmorphism and many of the well-described associated anomalies. Some of the abnormalities were unusual including a case with severe congenital mitral stenosis, two cases of eventration of the diaphragm, idiopathic thrombocytopaenic purpura and vitiligo. One child had an Arnold Chiari type 1 malformation and another had epibulbar dermoids, neither of which has previously been reported in this syndrome. There was a wide diversity of ethnic origin, with the syndrome being described in patients from the Pacific Islands for the first time. The cases described emphasize the broad range of associated anomalies found in Kabuki syndrome and further illustrate its presence in all ethnic groups.