Clinical and molecular delineation of mandibulofacial dysostosis with microcephaly in six Korean patients: When to consider EFTUD2 analysis?

Mandibulofacial dysostosis with microcephaly (MFDM, OMIM#610536) is an extremely rare genetic syndrome characterised by microcephaly, external ear deformity, hearing loss, and distinct facial appearance, including zygomatic hypoplasia and micrognathia. Occasionally, various malformations in other internal organs, including oesophageal atresia or tracheoesophageal fistula, may lead to life-threatening situations. Haploinsufficiency of EFTUD2 is responsible for MFDM. Here, we present the phenotypic and genetic characteristics of six Korean children who were diagnosed with MFDM by molecular genetic testing. All but one patient had occipitofrontal circumferences below the ?2.0 standard deviation score. Micrognathia was identified in all patients. A cleft palate (66.7%) and other facial dysmorphisms, including facial asymmetry (50%) and malar hypoplasia (50%), were also frequently observed. Hearing loss was observed in all patients along with one or more internal and external ear deformities, including ossicular anomalies, auditory canal stenosis, and microtia. Two patients (33.3%) had undergone surgery for tracheoesophageal fistula type C. Most patients were initially misdiagnosed as other better-known syndromes with overlapping characteristics, such as Treacher Collins or CHARGE syndrome. The first three patients were diagnosed using exome sequencing. However, after increased awareness of MFDM in the first three patients, MFDM was considered one of the initial differential diagnoses and could be diagnosed by target gene analysis in the remaining three cases. Thus, we recommend targeted EFTUD2 analysis as the initial workup for the rapid diagnosis of MFDM in patients with facial dysostosis, microcephaly, and otologic problems.     

Biallelic variants in CENPF causing a phenotype distinct from Strømme syndrome

Biallelic loss-of-function (LoF) variants in CENPF gene are responsible for Strømme syndrome, a condition presenting with intestinal atresia, anterior ocular chamber anomalies, and microcephaly. Through an international collaboration, four individuals (three males and one female) carrying CENPF biallelic variants, including two missense variants in homozygous state and four LoF variants, were identified by exome sequencing. All individuals had variable degree of developmental delay/intellectual disability and microcephaly (ranging from −2.9 SDS to −5.6 SDS) and a recognizable pattern of dysmorphic facial features including inverted-V shaped interrupted eyebrows, epicanthal fold, depressed nasal bridge, and pointed chin. Although one of the cases had duodenal atresia, all four individuals did not have the combination of internal organ malformations of Strømme syndrome (intestinal atresia and anterior eye segment abnormalities). Immunofluorescence analysis on skin fibroblasts on one of the four cases with the antibody for ARL13B that decorates primary cilia revealed shorter primary cilia that are consistent with a ciliary defect. This case-series of individuals with biallelic CENPF variants suggests the spectrum of clinical manifestations of the disorder that may be related to CENPF variants is broad and can include phenotypes lacking the cardinal features of Strømme syndrome.     

EFTUD2 missense variants disrupt protein function and splicing in mandibulofacial dysostosis Guion‐Almeida type

Pathogenic variants in the core spliceosome U5 small nuclear ribonucleoprotein gene EFTUD2/SNU114 cause the craniofacial disorder mandibulofacial dysostosis Guion‐Almeida type (MFDGA). MFDGA‐associated variants in EFTUD2 comprise large deletions encompassing EFTUD2, intragenic deletions and single nucleotide truncating or missense variants. These variants are predicted to result in haploinsufficiency by loss‐of‐function of the variant allele. While the contribution of deletions within EFTUD2 to allele loss‐of‐function are self‐evident, the mechanisms by which missense variants are disease‐causing have not been characterized functionally. Combining bioinformatics software prediction, yeast functional growth assays, and a minigene (MG) splicing assay, we have characterized how MFDGA missense variants result in EFTUD2 loss‐of‐function. Only four of 19 assessed missense variants cause EFTUD2 loss‐of‐function through altered protein function when modeled in yeast. Of the remaining 15 missense variants, five altered the normal splicing pattern of EFTUD2 pre‐messenger RNA predominantly through exon skipping or cryptic splice site activation, leading to the introduction of a premature termination codon. Comparison of bioinformatic predictors for each missense variant revealed a disparity amongst different software packages and, in many cases, an inability to correctly predict changes in splicing subsequently determined by MG interrogation. This study highlights the need for laboratory‐based validation of bioinformatic predictions for EFTUD2 missense variants.     

“Mandibulofacial dysostosis with microcephaly” caused by EFTUD2 mutations: Expanding the phenotype

Heterozygous mutations in the EFTUD2 were identified in 12 individuals with a rare sporadic craniofacial condition termed Mandibulofacial dysostosis with microcephaly (MIM 610536). We present clinical and radiographic features of three additional patients with de novo heterozygous mutations in EFTUD2. Although clinical features overlap with findings of the original report (choanal atresia, cleft palate, maxillary and mandibular hypoplasia, and microtia), microcephaly was present in two of three patients and cognitive impairment was milder in those with head circumference proportional to height. Our cases expand the phenotypic spectrum to include epibulbar dermoids and zygomatic arch clefting. We suggest that craniofacial computed tomography studies to assess cleft of zygomatic arch may assist in making this diagnosis. We recommend consideration of EFTUD2 testing in individuals with features of oculo‐auriculo‐vertebral spectrum and bilateral microtia, or individuals with atypical CHARGE syndrome who do not have a CHD7 mutation, particularly those with a zygomatic arch cleft. The absence of microcephaly in one patient indicates that it is a highly variable phenotypic feature. © 2012 Wiley Periodicals, Inc.     

Misclassification risk of patients with bilateral cleft lip and palate and manifestations of median facial dysplasia: A new variant of del(22q11.2) syndrome?

The generic term median facial dysplasia (MFD) describes a subgroup of patients with cleft lip and palate exhibiting characteristic craniofacial defects: (1) short prolabium, (2) absence of frenulum labii, (3) hypoplasia of premaxilla, (4) absent upper central and lateral incisors of the cleft side, and (5) deficient septal cartilage and nasal spine. Gross brain malformations are usually absent in MFD. The same craniofacial malformations are also described in patients with holoprosencephaly sequence (HPE‐S). We report on two male patients with bilateral cleft lip and palate showing the facial findings of MFD or HPE‐S. Additional congenital malformations were anal atresia in one patient and severe cardiac defect in the other. In both, HPE was excluded by brain imaging, although uncommon brain anomalies were detected consisting of multiple white‐matter lesions in the one patient and unusual enlargement and tortuosity of intracerebral blood vessels in both patients. In addition to facial anomalies, the patients also had psychiatric problems typically seen in velo‐cardio‐facial syndrome (VCFS). Fluorescence in situ hybridization (FISH) analysis confirmed a 22q11.2 microdeletion in both. © 2001 Wiley‐Liss, Inc.     

Sibling recurrence of total anomalous pulmonary venous drainage

Many childhood syndromic disorders are associated with congenital heart defects, but few present specifically with total anomalous pulmonary venous drainage (TAPVD). Here, we report two siblings presenting with TAPVD, tracheo-oesophageal fistula and dysmorphic features in the neonatal period. Careful examination of the mother revealed subtle facial asymmetry and a pre-auricular tag, suggesting a potential variable expression of a dominant disorder. Whole exome sequencing identified a pathogenic heterozygous mutation in EFTUD2, a gene, normally associated with mandibulofacial dystosis Guion-Almedia type (MFDGA), in both siblings and the mother. This is the first report of TAPVD occurring as part of the MFDGA phenotype. It serves to highlight the importance of modern sequencing panels in identifying causative mutations for heterogeneous syndromes such as MFDGA and familial congenital heart defects whilst emphasising the relevance of variable expression when counselling parents.     

Retrospective evaluation of clinical and molecular data of 148 cases of esophageal atresia

Developmental abnormalities provide a unique opportunity to seek for the molecular mechanisms underlying human organogenesis. Esophageal development remains incompletely understood and elucidating causes for esophageal atresia (EA) in humans would contribute to achieve a better comprehension. Prenatal detection, syndromic classification, molecular diagnosis, and prognostic factors in EA are challenging. Some syndromes have been described to frequently include EA, such as CHARGE, EFTUD2-mandibulofacial dysostosis, Feingold syndrome, trisomy 18, and Fanconi anemia. However, no molecular diagnosis is made in most cases, including frequent associations, such as Vertebral-Anal-Cardiac-Tracheo-Esophageal-Renal-Limb defects (VACTERL). This study evaluates the clinical and genetic test results of 139 neonates and 9 fetuses followed-up at the Necker-Enfants Malades Hospital over a 10-years period. Overall, 52 cases were isolated EA (35%), and 96 were associated with other anomalies (65%). The latter group is divided into three subgroups: EA with a known genomic cause (9/148, 6%); EA with Vertebral-Anal-Cardiac-Tracheo-Esophageal-Renal-Limb defects (VACTERL) or VACTERL/Oculo-Auriculo-Vertebral Dysplasia (VACTERL/OAV) (22/148, 14%); EA with associated malformations including congenital heart defects, duodenal atresia, and diaphragmatic hernia without known associations or syndromes yet described (65/148, 44%). Altogether, the molecular diagnostic rate remains very low and may underlie frequent non-Mendelian genetic models.     

Large deletions encompassing the TCOF1 and CAMK2A genes are responsible for Treacher Collins syndrome with intellectual disability

Mandibulofacial dysostosis is part of a clinically and genetically heterogeneous group of disorders of craniofacial development, which lead to malar and mandibular hypoplasia. Treacher Collins syndrome is the major cause of mandibulofacial dysostosis and is due to mutations in the TCOF1 gene. Usually patients with Treacher Collins syndrome do not present with intellectual disability. Recently, the EFTUD2 gene was identified in patients with mandibulofacial dysostosis associated with microcephaly, intellectual disability and esophageal atresia. We report on two patients presenting with mandibulofacial dysostosis characteristic of Treacher Collins syndrome, but associated with unexpected intellectual disability, due to a large deletion encompassing several genes including the TCOF1 gene. We discuss the involvement of the other deleted genes such as CAMK2A or SLC6A7 in the cognitive development delay of the patients reported, and we propose the systematic investigation for 5q32 deletion when intellectual disability is associated with Treacher Collins syndrome.     

Mowat–Wilson syndrome in a Chinese population: A case series

Mowat–Wilson syndrome (MWS) is characterized clinically by a distinctive facial gestalt, intellectual disability, microcephaly, epilepsy, and nonobligatory congenital malformations such as Hirschsprung disease, urogenital anomalies, congenital heart disease, eye malformations. This article summarized the clinical features and molecular findings of 15 Chinese MWS patients. The results revealed a higher incidence of congenital heart disease in Chinese MWS patients compared to that previously reported in Caucasian cohorts, while the incidence of Hirschsprung disease and genitourinary malformation appeared to be lower. This suggests possible ethnicity‐related modifying effects in the MWS phenotype.     

Misclassification risk of patients with bilateral cleft lip and palate and manifestations of median facial dysplasia: A new variant of del(22q11.2) syndrome?

The generic term median facial dysplasia (MFD) describes a subgroup of patients with cleft lip and palate exhibiting characteristic craniofacial defects: (1) short prolabium, (2) absence of frenulum labii, (3) hypoplasia of premaxilla, (4) absent upper central and lateral incisors of the cleft side, and (5) deficient septal cartilage and nasal spine. Gross brain malformations are usually absent in MFD. The same craniofacial malformations are also described in patients with holoprosencephaly sequence (HPE-S). We report on two male patients with bilateral cleft lip and palate showing the facial findings of MFD or HPE-S. Additional congenital malformations were anal atresia in one patient and severe cardiac defect in the other. In both, HPE was excluded by brain imaging, although uncommon brain anomalies were detected consisting of multiple white-matter lesions in the one patient and unusual enlargement and tortuosity of intracerebral blood vessels in both patients. In addition to facial anomalies, the patients also had psychiatric problems typically seen in velo-cardio-facial syndrome (VCFS). Fluorescence in situ hybridization (FISH) analysis confirmed a 22q11.2 microdeletion in both.     

Female‐restricted syndromic intellectual disability in a patient from Thailand

Female‐restricted syndromic intellectual disability (ID) is a neurodevelopmental disorder with developmental delay (DD)/ID, facial dysmorphism, and diverse congenital anomalies comprising heart defects, anal anomalies, choanal atresia, postaxial polydactyly, scoliosis, and brain abnormalities. Loss‐of‐function mutations in the USP9X gene inherited as X‐linked dominance were identified as its etiology in females of different ethnic groups. Here, we report a 15‐year‐old Thai girl harboring a novel de novo heterozygous one‐base pair deletion (c.3508delG, p.Val1170TrpfsX9) in exon 23 of USP9X. Her profound DD, dysmorphic face including attached earlobes, short stature, and congenital malformations including s‐shaped thoracolumbar scoliosis, hip dislocation, and generalized brain atrophy shared common characteristics of X‐linked syndromic ID. We have observed severely malformed oro‐dental organs and a choledochal cyst, which have never been reported. Our study presents the first patient from Thailand expanding the phenotypic and mutational spectra of the syndrome.     

Human facial dysostoses

The human facial dysostoses can be subdivided into mandibulofacial dysostoses (MFDs) and acrofacial dysostoses (AFDs). The craniofacial phenotypes of the two groups of patients are similar. Both types are thought to be related to abnormal migration of neural crest cells to the pharyngeal arches and the face. The craniofacial anomalies shared by the two groups consist of downslanting palpebral fissures, coloboma of the lower eyelid, from which the eyelashes medial to the defect may be absent, hypoplasia of the zygomatic complex, micrognathia, and microtia, which is often associated with hearing loss. These facial deformities are associated with limb anomalies in the AFDs. All MFDs present with the typical craniofacial phenotype, but some have additional features that help to distinguish them clinically: intellectual disability, microcephaly, chest deformity, ptosis, cleft lip/palate, macroblepharon, or blepharophimosis. The limb anomalies in the AFDs can be classified into pre‐axial, post‐axial, and others not fitting into the first two AFD types. Of the pre‐axial types, Nager syndrome and of the post‐axial types, Miller syndrome are the best‐known disorders of their AFD subgroups. Several other AFDs with unknown molecular genetic bases, including lethal ones, have been described. This article reviews the MFDs and AFDs published to date.     

Fetal diagnosis of Mowat‐Wilson syndrome by whole exome sequencing

Mowat‐Wilson syndrome (MWS) is a complex genetic disorder associated with heterozygous variation in ZEB2. It is mainly characterized by moderate‐to‐severe intellectual disability, facial dysmorphism, epilepsy, and various malformations including Hirschsprung disease, corpus callosum anomalies, and congenital heart defects. It is rarely diagnosed prenatally and there is limited information available on the prenatal phenotype associated with MWS. Here we report the detection of a heterozygous de novo nonsense variant in ZEB2 by whole exome sequencing in a fetus with microphthalmia in addition to cardiac defects and typical MWS facial dysmorphism. As the prenatal phenotypic spectrum of MWS expands, the routine addition of fetal genomic testing particularly in the presence of multiple malformations will increase both the sensitivity and specificity of prenatal diagnostics.     

Array‐CGH is an effective first‐tier diagnostic test for EFTUD2‐associated congenital mandibulofacial dysostosis with microcephaly

Mandibulofacial dysostosis with microcephaly (MFDM) is a sporadic malformation syndrome with severe craniofacial abnormalities, microcephaly, developmental delay, and dysmorphic features. Most cases of clinically diagnosed MFDM remain genetically unexplained, and to the best of our knowledge a total of 35 patients, 31 different mutations, 4 deletions, and 6 reports have been published. Our proband was born at 36 weeks gestation with microcephaly, microcrania, cleft palate, severe retrognathia, oral and pharyngeal dysphagia, bilateral proximal radioulnar synostosis, 11 thoracic ribs, abnormal magnetic resonance imaging (MRI) findings including simplified gyral pattern and mild dilatation of the posterior bodies of the lateral ventricles secondary to thinning of the white matter, high‐pitched cry due to unilateral vocal cord paralysis, and dysmorphic features. Array comparative genomic hybridization (aCGH) + single nucleotide polymorphism (SNP) analysis identified a likely de novo pathogenic deletion on chromosome 17q21.31, encompassing the EFTUD2 gene. Our case represents the fifth reported proband to have MFDM caused by small deletions involving EFTUD2. All known mutations involving EFTUD2 result in genetic haploinsufficiency, consistent with our proband's case as well. Her phenotypic features both overlap and expand on the clinical features of previously reported cases, and her genetic diagnosis also supports the use of aCGH as a first‐tier testing option for this disorder.     

Refining critical regions in 15q24 microdeletion syndrome pertaining to autism

Chromosome 15q24 microdeletion syndrome is characterized by developmental delay, facial dysmorphism, hearing loss, hypotonia, recurrent infection, and other congenital malformations including microcephaly, scoliosis, joint laxity, digital anomalies, as well as sometimes having autism spectrum disorder (ASD) and attention deficit hyperactivity disorder. Here, we report a boy with a 2.58‐Mb de novo deletion at chromosome 15q24. He is diagnosed with ASD and having multiple phenotypes similar to those reported in cases having 15q24 microdeletion syndrome. To delineate the critical genes and region that might be responsible for these phenotypes, we reviewed all previously published cases. We observe a potential minimum critical region of 650 kb (LCR15q24A‐B) affecting NEO1 among other genes that might pertinent to individuals with ASD carrying this deletion. In contrast, a previously defined minimum critical region downstream of the 650‐kb interval (LCR15q24B‐D) is more likely associated with the developmental delay, facial dysmorphism, recurrent infection, and other congenital malformations. As a result, the ASD phenotype in this individual is potentially attributed by genes particularly NEO1 within the newly proposed critical region.     

Hepatic fibrosis in Kabuki syndrome

Kabuki (Niikawa-Kuroki) syndrome (KS) is characterized by a distinctive face, mental retardation, growth deficiency, skeletal anomalies, dermatoglyphic abnormalities, palatal anomalies, congenital heart defects, and urogenital malformations. Congenital hepatic abnormalities have been sporadically described in patients with KS from the literature, consisting of extrahepatic biliary atresia, neonatal sclerosing cholangitis, and severe neonatal jaundice. We report here on an additional patient with a congenital abnormality of the liver consisting of hepatic fibrosis. To our knowledge, idiopathic congenital hepatic fibrosis has not been reported in KS. Thus, our observation expands the spectrum of liver malformations found in KS with the inclusion of hepatic fibrosis and supports the evidence that hepatic abnormalities may not be uncommon in KS. Clinician should be advised to search for the specific facial anomalies of KS in patients with syndromic congenital hepatic diseases, and KS should be added to the list of previously recognized multiple congenital anomaly syndromes with hepatic involvement. Due to the frequent association with congenital heart malformations, KS should be considered in the evaluation of patients with neonatal liver disease and cardiac malformation. Due to the expression patterns of Notch genes, involvement of the Notch signaling pathway in the development of heart and liver anomalies in KS should be considered.     

Kaufman oculocerebrofacial syndrome: Novel UBE3B mutations and clinical features in four unrelated patients

The “blepharophimosis‐mental retardation” syndromes (BMRS) consist of a group of clinically and genetically heterogeneous congenital malformation syndromes, where short palpebral fissures and intellectual disability associate with a distinct set of other morphological features. Kaufman oculocerebrofacial syndrome represents a rare and recently reevaluated entity within the BMR syndromes and is caused by biallelic mutations of UBE3B. Affected individuals typically show microcephaly, impaired somatic growth, gastrointestinal and genitourinary problems, ectodermal anomalies and a characteristic face with short, upslanted palpebral fissures, depressed nasal bridge. and anteverted nares. Here we present four patients with five novel UBE3B mutations and propose the inclusion of clinical features to the characteristics of Kaufman oculocerebrofacial syndrome, including prominence of the cheeks and limb anomalies.