Ectodermal abnormalities in Kabuki syndrome

Reprogramming of the epigenome in neurodevelopmental disorders

The etiology of neurodevelopmental disorders (NDDs) remains a challenge for researchers. Human brain development is tightly regulated and sensitive to cellular alterations caused by endogenous or exogenous factors. Intriguingly, the surge of clinical sequencing studies has revealed that many of these disorders are monogenic and monoallelic. Notably, chromatin regulation has emerged as highly dysregulated in NDDs, with many syndromes demonstrating phenotypic overlap, such as intellectual disabilities, with one another. Here we discuss epigenetic writers, erasers, readers, remodelers, and even histones mutated in NDD patients, predicted to affect gene regulation. Moreover, this review focuses on disorders associated with mutations in enzymes involved in histone acetylation and methylation, and it highlights syndromes involving chromatin remodeling complexes. Finally, we explore recently discovered histone germline mutations and their pathogenic outcome on neurological function. Epigenetic regulators are mutated at every level of chromatin organization. Throughout this review, we discuss mechanistic investigations, as well as various animal and iPSC models of these disorders and their usefulness in determining pathomechanism and potential therapeutics. Understanding the mechanism of these mutations will illuminate common pathways between disorders. Ultimately, classifying these disorders based on their effects on the epigenome will not only aid in prognosis in patients but will aid in understanding the role of epigenetic machinery throughout neurodevelopment.

The Changing Landscape in the Genetic Etiology of Human Tooth Agenesis

Despite much progress in understanding the genetics of syndromic tooth agenesis (TA), the causes of the most common, isolated TA remain elusive. Recent studies have identified novel genes and variants contributing to the etiology of TA, and revealed new pathways in which tooth development genes belong. Further, the use of new research approaches including next-generation sequencing has provided increased evidence supporting an oligogenic inheritance model for TA, and may explain the phenotypic variability of the condition. In this review, we present current knowledge about the genetic mechanisms underlying syndromic and isolated TA in humans, and highlight the value of incorporating next-generation sequencing approaches to identify causative and/or modifier genes that contribute to the etiology of TA.

Craniofacial and dental features in kabuki syndrome patients

Objective : To describe oral manifestations in Brazilian individuals with Kabuki syndrome, a multiple congenital anomaly/mental retardation syndrome. Study Design : A total of 16 Kabuki syndrome individuals, aged between 8 to 24 years and of both sexes, were referred by the Department of Clinical Genetics for oral treatment and follow-up to the Oral Care Center for Inherited Diseases, University Hospital of Brasília, Brasília, Brazil. Each individual underwent complete physical examination, as well as intraoral and radiographic examinations. Results : Craniofacial and dental alterations were observed in all Kabuki syndrome patients examined. In addition, atypical shape of the molars' crowns, occlusal convergence of the premolars' crowns, and root dilaceration were also observed. Enamel diffuse opacities were observed in permanent dentition (n  =  10). Conclusion : A great clinical heterogeneity was observed in Kabuki syndrome individuals in line with previous studies in the literature. Further clinical and molecular studies are necessary in order to better understand the presence of dental anomalies in this syndrome.

Ectodermal abnormalities in patients with Kabuki syndrome

Kabuki syndrome (KS) is extensively described in the literature and characterized by a typical facial gestalt in combination with postnatal short stature, hypotonia, joint laxity, developmental delay, persistent fetal fingertip pads, and an ever-growing group of congenital abnormalities. In this study, we focus on some ectodermal manifestations that we have observed. We studied seven patients who fulfilled the clinical criteria for KS and undertook a detailed clinical, dental, cytogenetic, and immunoglobulin assessments. In addition, microscopic hair examinations were performed on all patients and compared with matched control patients. All patients had receding of the anterior hair line, but five had evident sparse frontal scalp hair. They all showed peculiar similar microscopic hair abnormalities in the form of twisting of the hair shafts, irregularity of the diameter of the hair, and trichorrhexis nodosa. In addition, hypoplastic nails, café-au-lait patches, and missing upper lateral incisors were observed in 57.1%, 28.6%, and 14.3% of the patients, respectively. Variable orodental anomalies were seen in all the patients with an everted lower lip found in four patients (57.1%). This report provides further evidence that some cases of KS have ectodermal involvement.

The C20orf133 gene is disrupted in a patient with Kabuki syndrome

Kabuki syndrome (KS) is a rare, congenital mental retardation syndrome. The aetiology of KS remains unknown. Four carefully selected patients with KS were screened for chromosomal imbalances using array comparative genomic hybridisation at 1 Mb resolution. In one patient, a 250 kb de novo microdeletion at 20p12.1 was detected, deleting exon 5 of C20orf133. The function of this gene is unknown. In situ hybridisation with the mouse orthologue of C20orf133 showed expression mainly in brain. The de novo nature of the deletion, the expression data and the fact that C20orf133 carries a macro domain, suggesting a role for the gene in chromatin biology, make the gene a likely candidate to cause the phenotype in this patient with KS. Both the finding of different of chromosomal rearrangements in patients with KS features and the absence of C20orf133 mutations in 19 additional patients with KS suggest that KS is genetically heterogeneous.

Dental evaluation of Kabuki syndrome patients

Kabuki syndrome is a genetic disorder of unknown etiology characterized by mental retardation, growth deficiency, and peculiar face (i.e., long palpebral fissures, eversion of the lateral third of the lower eyelids, prominent ears, and broad and depressed nasal tip). Oral manifestations commonly observed in Kabuki syndrome may comprise cleft lip/palate, bifid tongue and uvula, malocclusion, and dental abnormalities. We evaluated the dental findings of eight patients with Kabuki syndrome. One presented cleft palate; three presented caries; and seven had missing teeth, with the upper lateral incisors and inferior central incisors being the most commonly absent. All missing teeth were permanent, and there was no alteration of dental chronology or morphology. Because most patients had mixed dentition, the presence or absence of primary teeth was assessed through the parents' reports. One patient presented an absent upper canine, which had not been reported previously in the literature. Dental findings may be helpful for clinical diagnosis, or they may be an additional finding to substantiate the diagnosis of Kabuki syndrome in children with mild phenotype.

Kabuki syndrome with trichrome vitiligo, ectodermal defect and hypogammaglobulinemia A and G

We report a unique combination of symptoms in a case of Kabuki syndrome (KS), a multiple malformation/mental retardation syndrome that has a prevalence of 1:32,000 to 1:86,000. The patient was a mentally delayed 12-year-old male with trichrome vitiligo, ectodermal defect, and hypogammaglobulinemia A and G. This unique combination of signs, described here for the first time, indicates that KS comprises multiple deficits that affect not only the brain, but ectoderm-derived structures and the immune system as well. Our report may provide important clues for understanding the pathogenesis of the KS.

The C20orf133 gene is disrupted in a patient with Kabuki syndrome

BACKGROUND

Kabuki syndrome (KS) is a rare, clinically recognisable, congenital mental retardation syndrome. The aetiology of KS remains unknown.

METHODS

Four carefully selected patients with KS were screened for chromosomal imbalances using array comparative genomic hybridisation at 1 Mb resolution.

RESULTS

In one patient, a 250 kb de novo microdeletion at 20p12.1 was detected, deleting exon 5 of C20orf133. The function of this gene is unknown. In situ hybridisation with the mouse orthologue of C20orf133 showed expression mainly in brain, but also in kidney, eye, inner ear, ganglia of the peripheral nervous system and lung.

CONCLUSION

The de novo nature of the deletion, the expression data and the fact that C20orf133 carries a macro domain, suggesting a role for the gene in chromatin biology, make the gene a likely candidate to cause the phenotype in this patient with KS. Both the finding of different of chromosomal rearrangements in patients with KS features and the absence of C20orf133 mutations in 19 additional patients with KS suggest that KS is genetically heterogeneous.

Cutis laxa in Kabuki make-up syndrome

Kabuki make-up syndrome (KMS; OMIM#147920) is a multiple congenital anomalies/mental retardation syndrome of unknown cause, first described independently by Niikawa and Kuroki. It is characterized by a peculiar facial appearance, mild to moderate mental retardation, skeletal abnormality, joint laxity, short stature, and unusual dermatoglyphic patterns. Several additional malformations (eg, cleft palate), cardiovascular defects, genitourinary and gastrointestinal tract anomalies, otologic and ophthalmologic abnormalities, and recurrent infections are also frequently present. It is mostly sporadic, although some familial cases have been reported. Inheritance is thought to be autosomal dominant or X-linked recessive; several chromosomal abnormalities have been found, but none of them seems to be specific to KMS. The fact that the majority of patients are sporadic and show a wide spectrum of clinical features rules out the hypothesis that KMS is a condition with a microdeletion involving several contiguous genes. We recently observed an Italian boy with typical KMS associated with cutis laxa, which, to our knowledge, is an uncommon finding in KMS, never reported in more than 350 KMS cases previously described in the literature.

Kabuki make-up (Niikawa-Kuroki) syndrome: dental and craniofacial findings in a Brazilian child

This article reports the case of a Brazilian child diagnosed with Kabuki make-up syndrome (KMS), addressing the clinical features observed, with emphasis on the disease-specific oral and craniofacial manifestations. The patient had the distinctive KMS craniofacial appearance, mild delayed mental development, fingers with prominent fingertip pads and visual deficit. The dental findings included fusion of the left mandibular incisors (central and lateral), gemination of the right mandibular central incisor and congenital agenesis of the right mandibular lateral incisor, in the primary dentition, as well as absence of both permanent mandibular lateral incisors. Fusion and gemination have not been previously referred to as typical dental features in KMS. The detection of unique dental findings, such as missing teeth and dental anomalies of form in the primary dentition by means of clinical and radiographic examinations, might consist of a helpful diagnosis parameter in identifying children who may have milder forms of Kabuki syndrome.

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: 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.

Acanthosis Nigricans in Kabuki Syndrome

BACKGROUND

Acanthosis nigricans has been classified in different ways. All classifications depend on the clinical picture and the association with other conditions.

OBJECTIVE

We report a case of acanthosis nigricans in a patient with Kabuki syndrome. This syndrome is characterized by five main manifestations: typical facial features, post natal growth deficiency, skeletal abnormalities, dermatoglyphic abnormalities, and mild to moderate mental retardation.

CONCLUSION

Our case may suggest that acanthosis nigricans could be associated with Kabuki syndrome.

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.

Kabuki syndrome-like features associated with a small ring chromosome X and XIST gene expression

Although clinical features in Kabuki syndrome (KS; Niikawa-Kuroki syndrome) have been well defined, the underlying genetic mechanism still remains unclear. We report a 9-year-old girl with typical KS-like facial appearance, skeletal and dermatoglyphic abnormalities, severe mental retardation, and growth deficiency. In 60 of 100 GTG-banded metaphases from peripheral blood lymphocytes, a ring chromosome smaller than a G group chromosome was found, which, according to reverse painting, consisted of Xq11.1q13. The proband's karyotype was described as mos45,X/46,X,+r(X). Several loci were analyzed with fluorescence in situ hybridization (FISH) and microsatellite markers revealing that one r(X) breakpoint mapped proximal to DXS422 (Xp11.21) and the second mapped distal to XIST gene, between loci DXS128E and DXS441 (Xq13.2). Uniparental disomy for X and r(X) was excluded and the paternal origin of r(X) was identified. XIST expression was demonstrated by nested reverse transcription polymerase chain reaction (RT-PCR) using primers spanning exons 5, 6i, and 6 in RNA prepared from lymphocytes. The observation of XIST expression is in contrast to two other cases in which the XIST gene was either not present on r(X) or not expressed. To our knowledge, this is the first case of Kabuki-like syndrome manifestations with r(X) and XIST expression.

Speech patterns in Kabuki make-up syndrome: a case report

The case of a girl aged 3 years and 8 months with Kabuki make-up syndrome is reported. At presentation, she had normal cognitive functioning, and she also had a history of otitis media, a submucous cleft palate, and some hypotonia. Language testing showed normal receptive skills and good expressive vocabulary but poor morphosyntactic abilities. Speech analysis showed that she was capable of producing most of the sounds of her native language but demonstrated high variability in production of the sounds. In addition, she inconsistently simplified words by application of several phonologic processes. Possible explanations for the communication problems demonstrated are discussed.

Further evidence for autosomal dominant inheritance and ectodermal abnormalities in Kabuki syndrome

Most cases with Kabuki syndrome (KS) were reported sporadically. Recently, a few familial cases of KS were reported. This report provides further evidence that the KS is inherited as a dominant trait with variable expressivity. The proposita is an 18-month-old girl with facial findings characteristic of Kabuki syndrome, prominent fingertip-pads, a midsagittal cleft of vertebral body D4, hypotonia, and psychomotor retardation. Her mother had a similar facial appearance, prominent, cup-shaped ears, an abnormal dentition, early breast development, and low-normal intelligence. Because mother and daughter both had evident Kabuki syndrome, we conclude that KS in this family is inherited as a dominant trait. Further family history supports this finding. Microscopic examination of the hair of the proposita shows abnormalities consisting of trichorrhexis nodosa, twisting of the hairshafts, and irregularity of the diameter of the hair, as was described recently in a patient with KS. This could be another occasional finding in this syndrome, but further studies are required. The presence of abnormal hair, nails, and the commonly described tooth abnormalities in KS further suggest ectodermal involvement in this syndrome.

Kabuki syndrome: description of dental findings in 8 patients

The cardinal features of Kabuki (Niikawa-Kuroki) syndrome (KS) include characteristic facial dysmorphic features, mild to moderate mental deficiency, skeletal abnormalities, dermatoglyphic abnormalities, and postnatal growth retardation. We identified 8 patients with KS in a genetics clinic over the past 5 years. All were Caucasians, except for 2 who were of mixed Aboriginal and Caucasian descent. All had the facial gestalt, the dermatoglyphic abnormalities characteristic of the syndrome, and developmental delay. Dental abnormalities of permanent teeth were seen in all 8 cases; 6 had missing lower incisors. Five patients had uniquely abnormal upper incisor teeth shape; the upper incisors had a 'flat head' screwdriver-shaped appearance. Other dental abnormalities included missing lower lateral incisors, missing second premolars, and ectopic upper 6-year molars. We believe the presence of the unique dental findings will prove useful in the diagnostic assessment of individuals with KS.