Audiological phenotyping evaluation in KBG syndrome: Description of a multicenter review.

OBJECTIVES: Our objective was to reinforce clinical knowledge of hearing impairment in KBG syndrome. KBG syndrome is a rare genetic disorder due to monoallelic pathogenic variations of ANKRD11.The typical phenotype includes facial dysmorphism, costal and spinal malformation and developmental delay. Hearing loss in KBG patients has been reported for many years, but no study has evaluated audiological phenotyping from a clinical and an anatomical point of view. METHODS: This French multicenter study included 32 KBG patients with retrospective collection of data on audiological features, ear imaging and genetic investigations. RESULTS: We identified a typical audiological profil in KBG syndrome: conductive (71%), bilateral (81%), mild to moderate (84%) and stable (69%) hearing loss, with some audiological heterogeneity. Among patients with an abnormality on CT imaging (55%), ossicular chain impairment (67%), fixation of the stapes footplate (33%) and inner-ear malformations (33%) were the most common abnormalities. CONCLUSION: We recommend a complete audiological and radiological evaluation and an ENT-follow up in all patients presenting with KBG Syndrome. Imaging evaluation is necessary to determine the nature of lesions in the middle and inner ear.

Fraser syndrome without cryptophthalmos: Two cases.

Fraser syndrome (MIM#219000) is an autosomal recessive disorder, characterized by the association of cryptophthtalmos, syndactyly of the four extremities, urinary tract abnormalities and laryngo-tracheal anomalies. This condition is due to homozygous or compound heterozygous mutations in the FRAS/FREM complex genes: FRAS1, FREM2 and GRIP1. Here we report two atypical cases of Fraser syndrome due to mutations in the FRAS1 gene without cryptophthalmos. The first proband had syndactyly of three extremities, bilateral nostril coloboma, dysplastic ears with bilateral conductive hearing loss, blepharophimosis and lacrimal duct abnormalities. FRAS1 sequencing identified two pathogenic compound heterozygous variants: a nonsense variant in exon 70 and a missense variant in exon 24. The second proband had membranous syndactyly of the four extremities, left renal agenesis, laryngeal and ano-rectal malformations, dysplastic ears and bilateral conductive hearing loss. FRAS1 sequencing identified a pathogenic homozygous variant in the last exon of the gene. This first description of molecularly confirmed cases with Fraser syndrome without cryptophthalmos could contribute to further delineation of the clinical spectrum of Fraser syndrome, especially for possible phenotypically milder cases. Larger cohorts are required to try to refer the hypothesis of genotype-phenotype correlation.

[Child psychiatry interventions in patients with 22q11 deletion syndrome: From treatment to prevention]. / Prise en charge pédopsychiatrique des patients présentant un syndrome microdélétionnel 22q11.2 : du soin à la prévention.

22q11.2DS is one of the more frequent genetic syndromes associated to psychiatric symptoms. It has been associated to an increased risk to develop schizophrenia in adolescence or early adulthood. However, psychiatric symptoms appear early on, and should be recognized as soon as possible by child psychiatrists in order to improve the present well-being of children and their family, and to prevent further risks of developing severe and chronic psychiatric diseases later on. In this paper, we present a review of the recent literature concerning the 22q11.2DS syndrome focused on the risk factors that may be associated to an increased risk of psychotic transition. We advocate for the development of systematic specialized child psychiatry consultations for these patients, included in networks with geneticists, adult psychiatrists, and family associations, in order to improve their psychiatric prognosis and to support the development of translational research.

Dermatological manifestations in cardiofaciocutaneous syndrome: a prospective multicentric study of 45 mutation-positive patients.

BACKGROUND: Data on dermatological manifestations of cardiofaciocutaneous syndrome (CFCS) remain heterogeneous and almost without expert dermatological classification. OBJECTIVES: To describe the dermatological manifestations of CFCS; to compare them with the literature findings; to assess those discriminating CFCS from other RASopathies, including Noonan syndrome (NS) and Costello syndrome (CS); and to test for dermatological phenotype-genotype correlations. METHODS: We performed a 4-year, large, prospective, multicentric, collaborative dermatological and genetic study. RESULTS: Forty-five patients were enrolled. Hair abnormalities were ubiquitous, including scarcity or absence of eyebrows and wavy or curly hair in 73% and 69% of patients, respectively. Keratosis pilaris (KP), ulerythema ophryogenes (UO), palmoplantar hyperkeratosis (PPHK) and multiple melanocytic naevi (MMN; over 50 naevi) were noted in 82%, 44%, 27% and 29% of patients, respectively. Scarcity or absence of eyebrows, association of UO and PPHK, diffuse KP and MMN best differentiated CFCS from NS and CS. Oral acitretin may be highly beneficial for therapeutic management of PPHK, whereas treatment of UO by topical sirolimus 1% failed. No significant dermatological phenotype-genotype correlation was determined. CONCLUSIONS: A thorough knowledge of CFCS skin manifestations would help in making a positive diagnosis and differentiating CFCS from CS and NS.

The association of severe encephalopathy and question mark ear is highly suggestive of loss of MEF2C function.

Auriculocondylar syndrome and isolated question mark ear result from dysregulation of the endothelin 1-endothelin receptor type A signaling pathway. Animal models have highlighted the role of the transcription factor MEF2C as an effector of this pathway. We report heterozygous MEF2C loss-of-function as a possible cause of question mark ear associated with intellectual deficiency.

Molecular, clinical and neuropsychological study in 31 patients with Kabuki syndrome and KMT2D mutations.

Kabuki syndrome (KS-OMIM 147920) is a rare developmental disease characterized by the association of multiple congenital anomalies and intellectual disability. This study aimed to investigate intellectual performance in children with KS and link the performance to several clinical features and molecular data. We recruited 31 children with KMT2D mutations who were 6 to 16 years old. They all completed the Weschler Intelligence Scale for Children, fourth edition. We calculated all indexes: the Full Scale Intellectual Quotient (FSIQ), Verbal Comprehension Index (VCI), Perceptive Reasoning Index (PRI), Processing Speed Index (PSI), and Working Memory Index (WMI). In addition, molecular data and several clinical symptoms were studied. FSIQ and VCI scores were 10 points lower for patients with a truncating mutation than other types of mutations. In addition, scores for FSIQ, VCI and PRI were lower for children with visual impairment than normal vision. We also identified a discrepancy in indexes characterized by high WMI and VCI and low PRI and PSI. We emphasize the importance of early identification and intensive care of visual disorders in patients with KS and recommend individual assessment of intellectual profile.

Genetic counselling difficulties and ethical implications of incidental findings from array-CGH: a 7-year national survey.

Microarray-based comparative genomic hybridization (aCGH) is commonly used in diagnosing patients with intellectual disability (ID) with or without congenital malformation. Because aCGH interrogates with the whole genome, there is a risk of being confronted with incidental findings (IF). In order to anticipate the ethical issues of IF with the generalization of new genome-wide analysis technologies, we questioned French clinicians and cytogeneticists about the situations they have faced regarding IF from aCGH. Sixty-five IF were reported. Forty corresponded to autosomal dominant diseases with incomplete penetrance, 7 to autosomal dominant diseases with complete penetrance, 14 to X-linked diseases, and 4 were heterozygotes for autosomal recessive diseases with a high prevalence of heterozygotes in the population. Therapeutic/preventive measures or genetic counselling could be argued for all cases except four. These four IF were intentionally not returned to the patients. Clinicians reported difficulties in returning the results in 29% of the cases, mainly when the question of IF had not been anticipated. Indeed, at the time of the investigation, only 48% of the clinicians used consents mentioning the risk of IF. With the emergence of new technologies, there is a need to report such national experiences; they show the importance of pre-test information on IF.

[Kabuki syndrome: Update and review]. / Le syndrome Kabuki : mise au point et revue de la littérature.

Kabuki syndrome (OMIM: 147920) is a rare condition, mainly associating intellectual deficiency, a polymalformative syndrome, and specific morphological changes in the face. It nevertheless has a strong clinical and biological heterogeneity with rarer but very different symptoms (endocrinological anomalies, autoimmune disorders, obesity, etc.). Clinical diagnosis is difficult because it is based on a spectrum of clinical, radiological, and biological factors. Complications are numerous, sometimes interpenetrating, and early diagnosis of the disease is essential for optimal management. The development of genetic testing is therefore essential for the diagnosis of this disease. Recently, exome sequencing has helped identify two genes responsible for the disease: KMT2D (lysine (K)-specific methyltransferase 2D, better known as MLL2 - mixed lineage leukemia), and KDM6A (lysine-specific demethylase 6A). Functional studies of these genes should help clarify their role in the pathogenesis of the disease, in particular to test the hypothesis of epigenetic changes during embryogenesis and development. Finally, understanding the interactions between KMT2D and its target genes could unravel other candidate genes for hitherto unexplained Kabuki syndrome cases.

Clinical spectrum of eye malformations in four patients with Mowat-Wilson syndrome.

Mowat-Wilson syndrome (MWS) is a rare genetic syndrome characterized by a specific facial gestalt, intellectual deficiency, Hirschsprung disease and multiple congenital anomalies. Heterozygous mutations or deletions in the zinc finger E-box-binding homeobox2 gene (ZEB2) cause MWS. ZEB2 encodes for Smad-interacting protein 1, a transcriptional co-repressor involved in TGF-beta and BMP pathways and is strongly expressed in early stages of development in mice. Eye abnormalities have rarely been described in patients with this syndrome. Herein, we describe four patients (two males and two females; mean age 7 years) with MWS and eye malformations. Ocular anomalies included, iris/retinal colobomas, atrophy or absence of the optic nerve, hyphema, and deep refraction troubles, sometimes with severe visual consequences. All eye malformations were asymmetric and often unilateral and all eye segments were affected, similarly to the nine MWS cases with ophthalmological malformations previously reported (iris/chorioretinal/optic disc coloboma, optic nerve atrophy, retinal epithelium atrophy, cataract, and korectopia). In human embryo, ZEB2 is expressed in lens and neural retina. Using the present report and data from the literature, we set out to determine whether or not the presence of eye manifestations could be due to specific type or location of mutations. We concluded that the presence of eye malformations, although a rare feature in MWS, should be considered as a part of the clinical spectrum of the condition.

A review of craniofacial disorders caused by spliceosomal defects.

The spliceosome is a large ribonucleoprotein complex that removes introns from pre-mRNA transcripts. Mutations in EFTUD2, encoding a component of the major spliceosome, have recently been identified as the cause of mandibulofacial dysostosis, Guion-Almeida type (MFDGA), characterized by mandibulofacial dysostosis, microcephaly, external ear malformations and intellectual disability. Mutations in several other genes involved in spliceosomal function or linked aspects of mRNA processing have also recently been identified in human disorders with specific craniofacial malformations: SF3B4 in Nager syndrome, an acrofacial dysostosis (AFD); SNRPB in cerebrocostomandibular syndrome, characterized by Robin sequence and rib defects; EIF4A3 in the AFD Richieri-Costa-Pereira syndrome, characterized by Robin sequence, median mandibular cleft and limb defects; and TXNL4A in Burn-McKeown syndrome, involving specific craniofacial dysmorphisms. Here, we review phenotypic and molecular aspects of these syndromes. Given the apparent sensitivity of craniofacial development to defects in mRNA processing, it is possible that mutations in other proteins involved in spliceosomal function will emerge in the future as causative for related human disorders.

Systematic molecular and cytogenetic screening of 100 patients with marfanoid syndromes and intellectual disability.

The association of marfanoid habitus (MH) and intellectual disability (ID) has been reported in the literature, with overlapping presentations and genetic heterogeneity. A hundred patients (71 males and 29 females) with a MH and ID were recruited. Custom-designed 244K array-CGH (Agilent®; Agilent Technologies Inc., Santa Clara, CA) and MED12, ZDHHC9, UPF3B, FBN1, TGFBR1 and TGFBR2 sequencing analyses were performed. Eighty patients could be classified as isolated MH and ID: 12 chromosomal imbalances, 1 FBN1 mutation and 1 possibly pathogenic MED12 mutation were found (17%). Twenty patients could be classified as ID with other extra-skeletal features of the Marfan syndrome (MFS) spectrum: 4 pathogenic FBN1 mutations and 4 chromosomal imbalances were found (2 patients with both FBN1 mutation and chromosomal rearrangement) (29%). These results suggest either that there are more loci with genes yet to be discovered or that MH can also be a relatively non-specific feature of patients with ID. The search for aortic complications is mandatory even if MH is associated with ID since FBN1 mutations or rearrangements were found in some patients. The excess of males is in favour of the involvement of other X-linked genes. Although it was impossible to make a diagnosis in 80% of patients, these results will improve genetic counselling in families.

[Malformation syndromes associated with childhood cancer: an update]. / Anomalies de développement et prédisposition aux tumeurs de l'enfant.

Biology, genetics and environment of childhood solid tumours set them apart from adult solid tumours. The nature of the progenitor cells from which these tumours arise, and their immature tissue environment, allows childhood solid tumours to develop with fewer defects in cell regulatory processes. Constitutional molecular defects are known to play a role in childhood solid tumours, as shown by the increased incidence of embryonic cancers in children carrying malformations associated with childhood cancer. These rare diagnoses are commonly missed. In this article, we reviewed the spectrum of these tumour predisposition syndromes.

microRNAs in diseases: from candidate to modifier genes.

Until recently, the search for genetic factors predisposing or causing Mendelian diseases focused almost exclusively on protein coding sequences. As essential components of the regulatory system of gene expression, microRNAs (miRNAs) hold great promises into elucidating a number of inherited diseases. The herein review focuses on the genetic variations, whether copy number variation (CNV) or single nucleotide polymorphism (SNP), alternatively at the levels of the miRNA gene itself and of its target genes. We consider miRNA as the candidate gene, or the regulator of a disease-causing gene, or the modifier gene. The best paradigms of the field are presented in both monogenic diseases and complex traits. The computational tools, which are essential into identifying miRNAs and characterizing miRNA targets, are overviewed.

Mutation update for the CSB/ERCC6 and CSA/ERCC8 genes involved in Cockayne syndrome.

Cockayne syndrome is an autosomal recessive multisystem disorder characterized principally by neurological and sensory impairment, cachectic dwarfism, and photosensitivity. This rare disease is linked to mutations in the CSB/ERCC6 and CSA/ERCC8 genes encoding proteins involved in the transcription-coupled DNA repair pathway. The clinical spectrum of Cockayne syndrome encompasses a wide range of severity from severe prenatal forms to mild and late-onset presentations. We have reviewed the 45 published mutations in CSA and CSB to date and we report 43 new mutations in these genes together with the corresponding clinical data. Among the 84 reported kindreds, 52 (62%) have mutations in the CSB gene. Many types of mutations are scattered along the whole coding sequence of both genes, but clusters of missense mutations can be recognized and highlight the role of particular motifs in the proteins. Genotype-phenotype correlation hypotheses are considered with regard to these new molecular and clinical data. Additional cases of molecular prenatal diagnosis are reported and the strategy for prenatal testing is discussed. Two web-based locus-specific databases have been created to list all identified variants and to allow the inclusion of future reports (www.umd.be/CSA/ and www.umd.be/CSB/).

Molecular analysis of pericentrin gene (PCNT) in a series of 24 Seckel/microcephalic osteodysplastic primordial dwarfism type II (MOPD II) families.

Microcephalic osteodysplastic primordial dwarfism type II (MOPD II, MIM 210720) and Seckel syndrome (SCKL, MIM 210600) belong to the primordial dwarfism group characterised by intrauterine growth retardation, severe proportionate short stature, and pronounced microcephaly. MOPD II is distinct from SCKL by more severe growth retardation, radiological abnormalities, and absent or mild mental retardation. Seckel syndrome is associated with defective ATR dependent DNA damage signalling. In 2008, loss-of-function mutations in the pericentrin gene (PCNT) have been identified in 28 patients, including 3 SCKL and 25 MOPDII cases. This gene encodes a centrosomal protein which plays a key role in the organisation of mitotic spindles. The aim of this study was to analyse PCNT in a large series of SCKL-MOPD II cases to further define the clinical spectrum associated with PCNT mutations. Among 18 consanguineous families (13 SCKL and 5 MOPDII) and 6 isolated cases (3 SCKL and 3 MOPD II), 13 distinct mutations were identified in 5/16 SCKL and 8/8 MOPDII including five stop mutations, five frameshift mutations, two splice site mutations, and one apparent missense mutation affecting the last base of exon 19. Moreover, we demonstrated that this latter mutation leads to an abnormal splicing with a predicted premature termination of translation. The clinical analysis of the 5 SCKL cases with PCNT mutations showed that they all presented minor skeletal changes and clinical features compatible with MOPDII diagnosis. It is therefore concluded that, despite variable severity, MOPDII is a genetically homogeneous condition due to loss-of-function of pericentrin.

Long-range regulation at the SOX9 locus in development and disease.

The involvement of SOX9 in congenital skeletal malformation was demonstrated 15 years ago with the identification of mutations in and around the gene in patients with campomelic dysplasia (CD). Translocations upstream of the coding sequence suggested that altered expression of SOX9 was capable of severely impacting on skeletal development. Subsequent studies in humans and animal models pointed towards a complex regulatory region controlling SOX9 transcription, involving approximately 1 Mb of upstream sequence. Recent data indicate that this regulatory domain may extend substantially further, with identification of several disruptions greater than 1 Mb upstream of SOX9 associated with isolated Pierre Robin sequence (PRS), a craniofacial disorder that is frequently a component of CD. The translocation breakpoints upstream of SOX9 can now be clustered into three groups, with a trend towards less severe skeletal phenotypes as the distance of each cluster from SOX9 increases. In this review we discuss how the identification of novel lesions surrounding SOX9 support the existence of tissue specific enhancers acting over a large distance to regulate expression of the gene during craniofacial development, and we highlight the potential for discovery of additional regulatory elements within the extended SOX9 control region.

19q13.11 deletion syndrome: a novel clinically recognisable genetic condition identified by array comparative genomic hybridisation.

BACKGROUND: Deletions of chromosome 19 have rarely been reported, with the exception of some patients with deletion 19q13.2 and Blackfan-Diamond syndrome due to haploinsufficiency of the RPS19 gene. Such a paucity of patients might be due to the difficulty in detecting a small rearrangement on this chromosome that lacks a distinct banding pattern. Array comparative genomic hybridisation (CGH) has become a powerful tool for the detection of microdeletions and microduplications at high resolution in patients with syndromic mental retardation. METHODS AND RESULTS: Using array CGH, this study identified three interstitial overlapping 19q13.11 deletions, defining a minimal critical region of 2.87 Mb, associated with a clinically recognisable syndrome. The three patients share several major features including: pre- and postnatal growth retardation with slender habitus, severe postnatal feeding difficulties, microcephaly, hypospadias, signs of ectodermal dysplasia, and cutis aplasia over the posterior occiput. Interestingly, these clinical features have also been described in a previously reported patient with a 19q12q13.1 deletion. No recurrent breakpoints were identified in our patients, suggesting that no-allelic homologous recombination mechanism is not involved in these rearrangements. CONCLUSIONS: Based on these results, the authors suggest that this chromosomal abnormality may represent a novel clinically recognisable microdeletion syndrome caused by haploinsufficiency of dosage sensitive genes in the 19q13.11 region.