Dysmorphology at a distance: results of a web-based diagnostic service

In 2007, the DYSCERNE pilot project funded by the European Commission Public Health Executive Agency (EU DG Sanco) aimed at setting up a network of expertise for patients with rare dysmorphic disorders. As part of DYSCERNE, a Dysmorphology Diagnostic System (DDS) was set up to enable clinicians throughout the EU to submit cases electronically for diagnosis using a secure, web-based interface, hosted at specified access points (Submitting nodes), in 26 different European countries. We report the outcome of this service for 200 cases submitted consecutively between January 2010 and 2012. Each case was reviewed by an average of five expert reviewers. An average of three possible syndromic diagnoses was suggested per case. In 22.5% of the cases, a consensus clinical diagnosis was reached. Genetic testing was suggested in 70.5% of the cases, whereas other laboratory investigations and diagnostic imaging were recommended in 35.5 and 26% of the cases, respectively. Further specialized opinions were suggested in 23.5% of the cases. Overall, a total of 181 very rare or extremely rare genetic syndromes were considered in the differential diagnosis of the 200 cases. In two cases, the reviewers suggested that the findings represented a new syndrome, and in one of these syndromes the underlying genetic cause was subsequently identified. Other benefits of the submission process included the possibility of directing the case submitters to specific centres for diagnostic testing or participation in research and educational benefit derived for both case submitters and reviewers.     

The pathogenesis of craniosynostosis in the fetus.

Craniosynostosis occurs in approximately 1:2000 live births. It may affect the coronal, sagittal, metopic and lambdoid sutures in isolation or in combination. Although non-syndromic synostoses are more common, over 150 genetic syndromes have been identified. Recent advances in genetic mapping have linked chromosomal mutations with craniosynostotic syndromes. Despite the identification of these genetic mutations, the fundamental biomolecular mechanisms mediating cranial suture biology remain unknown. Today, many laboratories are investigating murine cranial suture biology as a model for human cranial suture development and fusion. Normal murine cranial suture biology is very complex, but evidence suggests that the dura mater provides the biomolecular blueprints (e.g. the soluble growth factors), which guide the fate of the pleuripotent osteogenic fronts. While our knowledge of these dura-derived signals has increased dramatically in the last decade, we have barely begun to understand the fundamental mechanisms that mediate cranial suture fusion or patency. Interestingly, recent advances in both premature human and programmed murine suture fusion have revealed unexpected results, and have generated more questions than answers.     

Aortic dilation,genetic testing,and associated diagnoses

PurposeThe aims of this study were to determine the genetic diagnoses most frequently associated with aortic dilation in a large population and to describe the results of genetic testing in the same.MethodsA retrospective review of records from patients with known aortic dilation identified through an echocardiogram database was performed. During the study period, different chromosomal microarray platforms and molecular diagnostic techniques were used.ResultsA total of 715 patients (mean age, 9.7 years; 67% male) met study inclusion criteria. The overall frequency of underlying presumptive or confirmed genetic diagnoses was 17% (125/715). Molecular evaluation for possible underlying aortopathy-related disorders was performed in 9% of patients (66/715). Next-generation sequencing panels were performed in 16 patients, and pathogenic abnormalities were detected in 4 (25%). Microarrays were conducted in 10% of patients (72/715), with a total of 23 pathogenic copy-number variants identified in 19 patients (26%). Marfan syndrome was the most frequently recognized genetic disorder associated with aortic dilation, but other cytogenetic abnormalities and associated diagnoses also were identified.ConclusionThe differential diagnosis in patients with aortic dilation is broad and includes many conditions outside the common connective tissue disorder spectrum. A genetics evaluation should be considered to assist in the diagnostic evaluation.     

Coronal craniosynostosis due to TCF12 mutations in patients from Turkey

Craniosynostosis consists of premature fusion of one or more cranial sutures and can be seen as part of a syndrome or diagnosed as nonsyndromic (isolated). Although more than 180 craniosynostosis syndromes have been identified, 70% of the cases are diagnosed as nonsyndromic. On the other hand, genetic causes of the cases are mostly unknown and the overall frequency of the genetic diagnosis is around 25%. In this study, we used targeted Next Generation Sequencing (NGS) analysis to identify the genetic variations of two craniosynostosis cases. We have identified two different truncating mutations, a known NM_207036.1:c.778_779delAT;p.(Met260Valfs*5) and a novel NM_207036.1:c.1102_1108delTCACCTC;p.(Pro369Glnfs*26) TCF12 variants. Additionally, upon physical examination of these two cases, we have observed some shared clinical similarities as well as differences such as bilateral simian crease and hidden cleft palate. This is the first study that reports the TCF12 mutations in Turkish patients with coronal suture synostosis.     

Monozygotic twins discordant for a congenital cranial dysinnervation disorder with features of Moebius syndrome

Moebius syndrome is a congenital cranial dysinnervation disorder (CCDD) that presents with nonprogressive cranial nerve (CN) VI and VII palsies resulting in facial weakness and inability to abduct the eye(s). While many CCDDs have an underlying genetic cause, the etiology of Moebius syndrome remains unclear as most cases are sporadic. Here, we describe a pair of monochorionic, diamniotic twin girls; one with normal growth and development, and one with micrognathia, reduced facial expression, and poor feeding. Magnetic resonance imaging of the brain performed on the affected twin at 19 months of age showed severely hypoplastic or absent CN IV bilaterally, left CN VI smaller than right, and bilateral hypoplastic CN VII and IX, consistent with a diagnosis of a CCDD, most similar to that of Moebius syndrome. Genomic sequencing was performed on each twin and data was assessed for discordant variants, as well as variants in novel and CCDD-associated genes. No pathogenic, likely pathogenic, or variants of uncertain significance were identified in genes known to be associated with CCDDs or other congenital facial weakness conditions. This family provides further evidence in favor of a stochastic event as the etiology in Moebius syndrome, rather than a monogenic condition.     

Neurofibromatosis/Noonan phenotype: a variable feature of type 1 neurofibromatosis

Since January 1989 we have ascertained patients with neurofibromatosis type 1 (NFl) as part of our genetic register in the North West of England. This register has now identified 453 affected cases from 235 families. The first 94 individuals were specifically examined for features of the Noonan phenotype. This was present in 12/94 sequentially identified individuals with NFl, including six individuals from three families. However, three cases occurred in a further family, where Noonan syndrome appeared to segregate separately from NFl. We have provided evidence for the chance association of Noonan syndrome and NFl and that the Noonan phenotype occurs as a feature in some NFl families. However, there is now little evidence of a separate NFl/Noonan syndrome entity or of NFl features occurring in classical Noonan syndrome.     

Resolving clinical diagnoses for syndromic cleft lip and/or palate phenotypes using whole‐exome sequencing

Individuals from three families ascertained in Bogota, Colombia, showing syndromic phenotypes, including cleft lip and/or palate, were exome‐sequenced. In each case, sequencing revealed the underlying causal variation confirming or establishing diagnoses. The findings include very rare and novel variants providing insights into genotype and phenotype relationships. These include the molecular diagnosis of an individual with Nager syndrome and a family exhibiting an atypical incontinentia pigmenti phenotype with a missense mutation in IKBKG. IKBKG mutations are typically associated with preterm male death, but this variant is associated with survival for 8–15 days. The third family exhibits unusual phenotypic features and the proband received a provisional diagnosis of Pierre Robin sequence (PRS). Affected individuals share a novel deleterious mutation in IRF6. Mutations in IRF6 cause Van der Woude and popliteal pterygium syndrome and contribute to nonsyndromic cleft lip phenotypes but have not previously been associated with a PRS phenotype. Exome sequencing followed by in silico screening to identify candidate causal variant(s), and functional assay in some cases offers a powerful route to establishing molecular diagnoses. This approach is invaluable for conditions showing phenotypic and/or genetic heterogeneity including cleft lip and/or palate phenotypes where many underlying causal genes have not been identified.     

PHACE syndrome: Infantile hemangiomas associated with multiple congenital anomalies: Clues to the cause

Infantile hemangiomas (IH) are the most common vascular tumor of infancy with an estimated 80,000 annual diagnoses in the United States. The genetic mechanisms underlying IH and the related multi-organ birth defect syndromes, PHACE (an acronym for P osterior fossa brain malformations, segmental facial H emangiomas, A rterial anomalies, C ardiac defects, E ye anomalies, and sternal clefting or supraumbilical raphe) and LUMBAR (an acronym for L ower body hemangiomas, U rogenital anomalies, M yelopathy, B one deformities, A norectal malformations/ A rterial anomalies, R enal anomalies) remain unsolved. With advances in next generation sequencing (NGS), genomic alterations have been identified in a wide range of vascular anomaly syndromes. We hypothesize that PHACE is a genetic disorder, caused by somatic mutations, likely in cancer genetic pathways. Identification of the genetic etiology will lead to improved diagnosis in PHACE syndrome and development of targeted therapies for IH and related congenital anomalies.     

Screening of subtle copy number changes in Aicardi syndrome patients with a high resolution X chromosome array-CGH

Aicardi syndrome (AIC) is an uncommon neurodevelopmental disorder affecting almost exclusively females. Chief features include infantile spasms, corpus callosal agenesis, and chorioretinal abnormalities. AIC is a sporadic disorder and hypothesized to be caused by heterozygous mutations in an X-linked gene but up to now without any defined candidate region on the X chromosome. Array based comparative genomic hybridisation (array-CGH) has become the method of choice for the detection of microdeletions and microduplications at high resolution. In this study, for the first time, 18 AIC patients were analyzed with a full coverage X chromosomal BAC arrays at a theoretical resolution of 82 kb. Copy number changes were validated by real-time quantitation (qPCR). No disease associated aberrations were identified. For such conditions as AIC, in which there are no familial cases, additional patients should be studied in order to identify rare cases with submicroscopic abnormalities, and to pursue a positional candidate gene approach.     

Genetic diagnoses and associated anomalies in fetuses prenatally diagnosed with esophageal atresia

Esophageal atresia (EA) is a congenital anomaly occurring in 2.3 per 10,000 live births. Due to advances in prenatal imaging, EA is more readily diagnosed, but data on the associated genetic diagnoses, other anomalies, and postnatal outcome for fetuses diagnosed prenatally with EA are scarce. We collected data from two academic medical centers (n = 61). Our data included fetuses with suspected EA on prenatal imaging that was confirmed postnatally and had at least one genetic test. In our cohort of 61 cases, 29 (49%) were born prematurely and 19% of those born alive died in the first 9 years of life. The most commonly associated birth defects were cardiac anomalies (67%) and spine anomalies (50%). A diagnosis was made in 61% of the cases; the most common diagnoses were vertebral defects, anal atresia, cardiac anomalies, tracheoesophageal fistula with esophageal atresia, radial or renal dysplasia, and limb anomalies association (43%, although 12% met only 2 of the criteria), trisomy 21 (5%), and CHARGE syndrome (5%). Our findings suggest that most fetuses with prenatally diagnosed EA have one or more additional major anomaly that warrants a more comprehensive clinical genetics evaluation. Fetuses diagnosed prenatally appear to represent a cohort with a worse outcome.     

In vivo modulation of FGF biological activity alters cranial suture fate

Gain-of-function mutations in fibroblast growth factor receptors have been identified in numerous syndromes associated with premature cranial suture fusion. Murine models in which the posterior frontal suture undergoes programmed fusion after birth while all other sutures remain patent provide an ideal model to study the biomolecular mechanisms that govern cranial suture fusion. Using adenoviral vectors and targeted in utero injections in rats, we demonstrate that physiological posterior frontal suture fusion is inhibited using a dominant-negative fibroblast growth factor receptor-1 construct, whereas the normally patent coronal suture fuses when infected with a construct that increases basic fibroblast growth factor biological activity. Our data may facilitate the development of novel, less invasive treatment options for children with craniosynostosis.     

HTAD patient pathway: Strategy for diagnostic work-up of patients and families with (suspected) heritable thoracic aortic diseases (HTAD). A statement from the HTAD working group of VASCERN

Heritable thoracic aortic diseases (HTAD) are rare pathologies associated with thoracic aortic aneurysms and dissection, which can be syndromic or non-syndromic. They may result from genetic defects. Associated genes identified to date are classified into those encoding components of the (a) extracellular matrix (b) TGFβ pathway and (c) smooth muscle contractile mechanism. Timely diagnosis allows for prompt aortic surveillance and prophylactic surgery, hence improving life expectancy and reducing maternal complications as well as providing reassurance to family members when a diagnosis is ruled out. This document is an expert opinion reflecting strategies put forward by medical experts and patient representatives involved in the HTAD Rare Disease Working Group of VASCERN. It aims to provide a patient pathway that improves patient care by diminishing time to diagnosis, facilitating the establishment of a correct diagnosis using molecular genetics when possible, excluding the diagnosis in unaffected persons through appropriate family screening and avoiding overuse of resources. It is being recommended that patients are referred to an expert centre for further evaluation if they meet at least one of the following criteria: (1) thoracic aortic dissection (<70 years if hypertensive; all ages if non-hypertensive), (2) thoracic aortic aneurysm (all adults with Z score >3.5 or 2.5–3.5 if non-hypertensive or hypertensive and <60 years; all children with Z score >3), (3) family history of HTAD with/without a pathogenic variant in a gene linked to HTAD, (4) ectopia lentis without other obvious explanation and (5) a systemic score of >5 in adults and >3 in children. Aortic imaging primarily relies on transthoracic echocardiography with magnetic resonance imaging or computed tomography as needed. Genetic testing should be considered in those with a high suspicion of underlying genetic aortopathy. Though panels vary among centers, for patients with thoracic aortic aneurysm or dissection or systemic features these should include genes with a definitive or strong association to HTAD. Genetic cascade screening and serial aortic imaging should be considered for family screening and follow-up. In conclusion, the implementation of these strategies should help standardise the diagnostic work-up and follow-up of patients with suspected HTAD and the screening of their relatives.     

Cranial Suture Biology of the Aleutian Island Inhabitants

Research on cranial suture biology suggests there is biological and taxonomic information to be garnered from the heritable pattern of suture synostosis. Suture synostosis along with brain growth patterns, diet, and biomechanical forces influence phenotypic variability in cranial vault morphology. This study was designed to determine the pattern of ectocranial suture synostosis in skeletal populations from the Aleutian Islands. We address the hypothesis that ectocranial suture synostosis pattern will differ according to cranial vault shape. Ales Hrdlicka identified two phenotypes in remains excavated from the Aleutian Island. The Paleo‐Aleutians, exhibiting a dolichocranic phenotype with little prognathism linked to artifacts distinguished from later inhabitants, Aleutians, who exhibited a brachycranic phenotype with a greater amount of prognathism. A total of 212 crania representing Paleo‐Aleuts and Aleutian as defined by Hrdlicka were investigated for suture synostosis pattern following standard methodologies. Comparisons were performed using Guttmann analyses. Results revealed similar suture fusion patterns for the Paleo‐Aleut and Aleutian, a strong anterior to posterior pattern of suture fusion for the lateral‐anterior suture sites, and a pattern of early termination at the sagittal suture sites for the vault. These patterns were found to differ from that reported in the literature. Because these two populations with distinct cranial shapes exhibit similar patterns of suture synostosis it appears pattern is independent of cranial shape in these populations of Homo sapiens. These findings suggest that suture fusion patterns may be population dependent and that a standardized methodology, using suture fusion to determine age‐at‐death, may not be applicable to all populations. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Prader‐Willi syndrome genetic subtypes and clinical neuropsychiatric diagnoses in residential care adults

The historical diagnosis of Prader‐Willi syndrome (PWS), a complex genetic disorder, in adults is often achieved by clinical presentation rather than by genetic testing and thus limited genetic subtype‐specific psychometric investigations and treatment options. Genetic testing and clinical psychiatric evaluation using Diagnostic and Statistical Manual (DSM)‐IV‐TR criteria were undertaken on 72 adult residents (34 M; 38 F) from the Prader‐Willi Homes of Oconomowoc (PWHO), a specialty PWS group home system. Methylation specific‐multiplex ligation probe amplification and high‐resolution microarrays were analyzed for methylation status, 15q11‐q13 deletions and maternal uniparental disomy 15 (mUPD15). Seventy (33M; 37F) of 72 residents were genetically confirmed and 36 (51%) had Type I or Type II deletions; 29 (42%) with mUPD15 and 5 (7%) with imprinting defects from three separate families. Psychiatric comorbidities were classified as anxiety disorder (38%), excoriation (skin picking) (33%), intermittent explosive disorder ([30%‐predominantly among males at 45% compared with females at 16% [OR = 4.3, 95%CI 1.4‐13.1, P < 0.008]) and psychotic features (23%). Psychiatric diagnoses did not differ between mUPD15 vs deletion, but a greater number of psychiatric diagnoses were observed for the larger Type I (4.3) vs smaller Type II (3.6) deletions when age was controlled (F = 5.0, P < 0.04). Adults with PWS presented with uniformly higher rates of psychiatric comorbidities which differed by genetic subtype with gender‐specific trends.     

Unfavorable prognosis of CRTC1‐MAML2 positive mucoepidermoid tumors with CDKN2A deletions

The CRTC1‐MAML2 fusion oncogene underlies the etiology of mucoepidermoid salivary gland carcinoma (MEC) where it confers a favorable survival outcome as compared with fusion‐negative MEC. While these analyses suggested that detection of CRTC1‐MAML2 serves as a useful prognostic biomarker, we recently identified outlier cases of fusion‐positive MEC associated with advanced‐staged lethal disease. To identify additional genetic alterations that might cooperate with CRTC1‐MAML2 to promote disease progression, we performed a pilot high‐resolution oligonucleotide array CGH (aCGH) and PCR‐based genotyping study on 23 MEC samples including 14 fusion‐positive samples for which we had clinical outcome information. Unbiased aCGH analysis identified inactivating deletions within CDKN2A as a candidate poor prognostic marker which was confirmed by PCR‐based analysis (CDKN2A deletions in 5/5 unfavorable fusion‐positive cases and 0/9 favorable fusion‐positive cases). We did not detect either activating EGFR mutations, nor copy number gains at the EGFR or ERBB2 loci as poor prognostic features for fusion‐positive MEC in any of the tumor specimens. Prospective studies with larger case series will be needed to confirm that combined CRTC1‐MAML2 and CDKN2A genotyping will optimally stage this disease. © 2009 Wiley‐Liss, Inc.     

New insights into the relationship between suture closure and craniofacial dysmorphology in sagittal nonsyndromic craniosynostosis

Premature closure of the sagittal suture occurs as an isolated (nonsyndromic) birth defect or as a syndromic anomaly in combination with other congenital dysmorphologies. The genetic causes of sagittal nonsyndromic craniosynostosis (NSC) remain unknown. Although variation of the dysmorphic (scaphocephaly) skull shape of sagittal NSC cases has been acknowledged, this variation has not been quantitatively studied three‐dimensionally (3D). We have analyzed the computed tomography skull images of 43 infants (aged 0.9–9 months) with sagittal NSC using anatomical landmarks and semilandmarks to quantify and characterize the within‐sample phenotypic variation. Suture closure patterns were defined by dividing the sagittal suture into three sections (anterior, central, posterior) and coding each section as ‘closed’ or ‘fused’. Principal components analysis of the Procrustes shape coordinates representing the skull shape of 43 cases of NSC did not separate individuals by sex, chronological age, or dental stages of the deciduous maxillary first molar. However, analysis of suture closure pattern allowed separation of these data. The central section of the sagittal suture appears to be the first to fuse. Then, at least two different developmental paths towards complete fusion of the sagittal suture exist; either the anterior section or the posterior section is the second to fuse. Results indicate that according to the sequence of sagittal suture closure patterns, different craniofacial complex shapes are observed. The relationship between craniofacial shape and suture closure indicates not only which suture fused prematurely (in our case the sagittal suture), but also the pattern of the suture closure. Whether these patterns indicate differences in etiology cannot be determined with our data and requires analysis of longitudinal data, most appropriately of animal models where prenatal conditions can be monitored.