Three dimensional reconstructed MRI of an acrylic meniscal cartilage phantom: the effect of acquisition slice thickness upon accuracy of volume measurement

AUSTRALI

An emerging, recognizable facial phenotype in association with mutations in GLI-similar 3 ( GLIS3 )

Neonatal diabetes and hypothyroidism (NDH) syndrome was first described in 2003 in a consanguineous Saudi Arabian family where two out of four siblings were reported to have presented with proportionate IUGR, neonatal non-autoimmune diabetes mellitus, severe congenital hypothyroidism, cholestasis, congenital glaucoma, and polycystic kidneys. Liver disease progressed to hepatic fibrosis. The renal disease was characterised by enlarged kidneys and multiple small cysts with deficient cortico-medullary junction differentiation and normal kidney function. There was minor facial dysmorphism (depressed nasal bridge, large anterior fontanelle, long philtrum) reported but no facial photographs were published. Mutations in the transcription factor GLI-similar 3 (GLIS3) gene in the original family and two other families were subsequently reported in 2006. All affected individuals had neonatal diabetes, congenital hypothyroidism but glaucoma and liver and kidney involvement were less consistent features. Detailed descriptions of the facial dysmorphism have not been reported previously. In this report, we describe the common facial dysmorphism consisting of bilateral low-set ears, depressed nasal bridge with overhanging columella, elongated, upslanted palpebral fissures, persistent long philtrum with a thin vermilion border of the upper lip in a cohort of seven patients with GLIS3 mutations and report the emergence of a distinct, probably recognisable facial gestalt in this group which evolves with age

DNM1 encephalopathy: A new disease of vesicle fission.

ObjectiveTo evaluate the phenotypic spectrum caused by mutations in dynamin 1 (DNM1), encoding the presynaptic protein DNM1, and to investigate possible genotype-phenotype correlations and predicted functional consequences based on structural modeling.MethodsWe reviewed phenotypic data of 21 patients (7 previously published) with DNM1 mutations. We compared mutation data to known functional data and undertook biomolecular modeling to assess the effect of the mutations on protein function.ResultsWe identified 19 patients with de novo mutations in DNM1 and a sibling pair who had an inherited mutation from a mosaic parent. Seven patients (33.3%) carried the recurrent p.Arg237Trp mutation. A common phenotype emerged that included severe to profound intellectual disability and muscular hypotonia in all patients and an epilepsy characterized by infantile spasms in 16 of 21 patients, frequently evolving into Lennox-Gastaut syndrome. Two patients had profound global developmental delay without seizures. In addition, we describe a single patient with normal development before the onset of a catastrophic epilepsy, consistent with febrile infection-related epilepsy syndrome at 4 years. All mutations cluster within the GTPase or middle domains, and structural modeling and existing functional data suggest a dominant-negative effect on DMN1 function.ConclusionsThe phenotypic spectrum of DNM1-related encephalopathy is relatively homogeneous, in contrast to many other genetic epilepsies. Up to one-third of patients carry the recurrent p.Arg237Trp variant, which is now one of the most common recurrent variants in epileptic encephalopathies identified to date. Given the predicted dominant-negative mechanism of this mutation, this variant presents a prime target for therapeutic intervention

EXTL3 mutations cause skeletal dysplasia, immune deficiency, and developmental delay.

We studied three patients with severe skeletal dysplasia, T cell immunodeficiency, and developmental delay. Whole-exome sequencing revealed homozygous missense mutations affecting exostosin-like 3 (EXTL3), a glycosyltransferase involved in heparan sulfate (HS) biosynthesis. Patient-derived fibroblasts showed abnormal HS composition and altered fibroblast growth factor 2 signaling, which was rescued by overexpression of wild-type EXTL3 cDNA. Interleukin-2-mediated STAT5 phosphorylation in patients' lymphocytes was markedly reduced. Interbreeding of the extl3-mutant zebrafish (box) with Tg(rag2:green fluorescent protein) transgenic zebrafish revealed defective thymopoiesis, which was rescued by injection of wild-type human EXTL3 RNA. Targeted differentiation of patient-derived induced pluripotent stem cells showed a reduced expansion of lymphohematopoietic progenitor cells and defects of thymic epithelial progenitor cell differentiation. These data identify EXTL3 mutations as a novel cause of severe immune deficiency with skeletal dysplasia and developmental delay and underline a crucial role of HS in thymopoiesis and skeletal and brain development

A clinical and molecular characterisation of CRB1-associated maculopathy

To date, over 150 disease-associated variants in CRB1 have been described, resulting in a range of retinal disease phenotypes including Leber congenital amaurosis and retinitis pigmentosa. Despite this, no genotype–phenotype correlations are currently recognised. We performed a retrospective review of electronic patient records to identify patients with macular dystrophy due to bi-allelic variants in CRB1. In total, seven unrelated individuals were identified. The median age at presentation was 21 years, with a median acuity of 0.55 decimalised Snellen units (IQR = 0.43). The follow-up period ranged from 0 to 19 years (median = 2.0 years), with a median final decimalised Snellen acuity of 0.65 (IQR = 0.70). Fundoscopy revealed only a subtly altered foveal reflex, which evolved into a bull’s-eye pattern of outer retinal atrophy. Optical coherence tomography identified structural changes—intraretinal cysts in the early stages of disease, and later outer retinal atrophy. Genetic testing revealed that one rare allele (c.498_506del, p.(Ile167_Gly169del)) was present in all patients, with one patient being homozygous for the variant and six being heterozygous. In trans with this, one variant recurred twice (p.(Cys896Ter)), while the four remaining alleles were each observed once (p.(Pro1381Thr), p.(Ser478ProfsTer24), p.(Cys195Phe) and p.(Arg764Cys)). These findings show that the rare CRB1 variant, c.498_506del, is strongly associated with localised retinal dysfunction. The clinical findings are much milder than those observed with bi-allelic, loss-of-function variants in CRB1, suggesting this in-frame deletion acts as a hypomorphic allele. This is the most prevalent disease-causing CRB1 variant identified in the non-Asian population to date

Mutations of AKT3 are associated with a wide spectrum of developmental disorders including extreme megalencephaly

Mutations of genes within the phosphatidylinositol-3-kinase (PI3K)-AKT-MTOR pathway are well known causes of brain overgrowth (megalencephaly) as well as segmental cortical dysplasia (such as hemimegalencephaly, focal cortical dysplasia and polymicrogyria). Mutations of the AKT3 gene have been reported in a few individuals with brain malformations, to date. Therefore, our understanding regarding the clinical and molecular spectrum associated with mutations of this critical gene is limited, with no clear genotype–phenotype correlations. We sought to further delineate this spectrum, study levels of mosaicism and identify genotype–phenotype correlations of AKT3-related disorders. We performed targeted sequencing of AKT3 on individuals with these phenotypes by molecular inversion probes and/or Sanger sequencing to determine the type and level of mosaicism of mutations. We analysed all clinical and brain imaging data of mutation-positive individuals including neuropathological analysis in one instance. We performed ex vivo kinase assays on AKT3 engineered with the patient mutations and examined the phospholipid binding profile of pleckstrin homology domain localizing mutations. We identified 14 new individuals with AKT3 mutations with several phenotypes dependent on the type of mutation and level of mosaicism. Our comprehensive clinical characterization, and review of all previously published patients, broadly segregates individuals with AKT3 mutations into two groups: patients with highly asymmetric cortical dysplasia caused by the common p.E17K mutation, and patients with constitutional AKT3 mutations exhibiting more variable phenotypes including bilateral cortical malformations, polymicrogyria, periventricular nodular heterotopia and diffuse megalencephaly without cortical dysplasia. All mutations increased kinase activity, and pleckstrin homology domain mutants exhibited enhanced phospholipid binding. Overall, our study shows that activating mutations of the critical AKT3 gene are associated with a wide spectrum of brain involvement ranging from focal or segmental brain malformations (such as hemimegalencephaly and polymicrogyria) predominantly due to mosaic AKT3 mutations, to diffuse bilateral cortical malformations, megalencephaly and heterotopia due to constitutional AKT3 mutations. We also provide the first detailed neuropathological examination of a child with extreme megalencephaly due to a constitutional AKT3 mutation. This child has one of the largest documented paediatric brain sizes, to our knowledge. Finally, our data show that constitutional AKT3 mutations are associated with megalencephaly, with or without autism, similar to PTEN-related disorders. Recognition of this broad clinical and molecular spectrum of AKT3 mutations is important for providing early diagnosis and appropriate management of affected individuals, and will facilitate targeted design of future human clinical trials using PI3K-AKT pathway inhibitors

The phenotype of Floating-Harbor syndrome: Clinical characterization of 52 individuals with mutations in exon 34 of SRCAP

Background: Floating-Harbor syndrome (FHS) is a rare condition characterized by short stature, delays in expressive language, and a distinctive facial appearance. Recently, heterozygous truncating mutations in SRCAP were determined to be disease-causing. With the availability of a DNA based confirmatory test, we set forth to define the clinical features of this syndrome. Methods and results. Clinical information on fifty-two individuals with SRCAP mutations was collected using standardized questionnaires. Twenty-four males and twenty-eight females were studied with ages ranging from

Perspectives of US private payers on insurance coverage for pediatric and prenatal exome sequencing: Results of a study from the Program in Prenatal and Pediatric Genomic Sequencing (P3EGS).

PurposeExome sequencing (ES) has the potential to improve management of congenital anomalies and neurodevelopmental disorders in fetuses, infants, and children. US payers are key stakeholders in patient access to ES. We examined how payers view insurance coverage and clinical utility of pediatric and prenatal ES.MethodsWe employed the framework approach of qualitative research to conduct this study. The study cohort represented 14 payers collectively covering 170,000,000 enrollees.ResultsSeventy-one percent of payers covered pediatric ES despite perceived insufficient evidence because they saw merit in available interventions or in ending the diagnostic odyssey. None covered prenatal ES, because they saw no merit. For pediatric ES, 50% agreed with expanded aspects of clinical utility (e.g., information utility), and 21% considered them sufficient for coverage. For prenatal ES, payers saw little utility until in utero interventions become available.ConclusionThe perceived merit of ES is becoming a factor in payers' coverage for serious diseases with available interventions, even when evidence is perceived insufficient. Payers' views on ES's clinical utility are expanding to include informational utility, aligning with the views of patients and other stakeholders. Our findings inform clinical research, patient advocacy, and policy-making, allowing them to be more relevant to payers

The phenotype of floating-harbor syndrome:clinical characterization of 52 individuals with mutations in exon 34 of SRCAP

Background\ud Floating-Harbor syndrome (FHS) is a rare condition characterized by short stature, delays in expressive language, and a distinctive facial appearance. Recently, heterozygous truncating mutations in SRCAP were determined to be disease-causing. With the availability of a DNA based confirmatory test, we set forth to define the clinical features of this syndrome.\ud \ud Methods and results\ud Clinical information on fifty-two individuals with SRCAP mutations was collected using standardized questionnaires. Twenty-four males and twenty-eight females were studied with ages ranging from 2 to 52 years. The facial phenotype and expressive language impairments were defining features within the group. Height measurements were typically between minus two and minus four standard deviations, with occipitofrontal circumferences usually within the average range. Thirty-three of the subjects (63%) had at least one major anomaly requiring medical intervention. We did not observe any specific phenotype-genotype correlations.\ud \ud Conclusions\ud This large cohort of individuals with molecularly confirmed FHS has allowed us to better delineate the clinical features of this rare but classic genetic syndrome, thereby facilitating the development of management protocols.The authors would like to thank the families for their cooperation and permission to publish these findings. SdM would like to thank Barto Otten. Funding was provided by the Government of Canada through Genome Canada, the Canadian Institutes of Health Research (CIHR) and the Ontario Genomics Institute (OGI-049), by Genome Québec and Genome British Columbia, and the Manton Center for Orphan Disease Research at Children’s Hospital Boston. KMB is supported by a Clinical Investigatorship Award from the CIHR Institute of Genetics. AD is supported by NIH grant K23HD073351. BBAdV and HGB were financially supported by the AnEUploidy project (LSHG-CT-2006-37627). This work was selected for study by the FORGE Canada Steering Committee, which consists of K. Boycott (University of Ottawa), J. Friedman (University of British Columbia), J. Michaud (University of Montreal), F. Bernier (University of Calgary), M. Brudno (University of Toronto), B. Fernandez (Memorial University), B. Knoppers (McGill University), M. Samuels (Université de Montréal), and S. Scherer (University of Toronto). We thank the Galliera Genetic Bank - “Telethon Genetic Biobank Network” supported by Italian Telethon grants (project no. GTB07001) for providing us with specimens

Biallelic sequence variants in INTS1 in patients with developmental delays, cataracts, and craniofacial anomalies.

The Integrator complex subunit 1 (INTS1) is a component of the integrator complex that comprises 14 subunits and associates with RPB1 to catalyze endonucleolytic cleavage of nascent snRNAs and assist RNA polymerase II in promoter-proximal pause-release on protein-coding genes. We present five patients, including two sib pairs, with biallelic sequence variants in INTS1. The patients manifested absent or severely limited speech, an abnormal gait, hypotonia and cataracts. Exome sequencing revealed biallelic variants in INTS1 in all patients. One sib pair demonstrated a missense variant, p.(Arg77Cys), and a frameshift variant, p.(Arg1800Profs*20), another sib pair had a homozygous missense variant, p.(Pro1874Leu), and the fifth patient had a frameshift variant, p.(Leu1764Cysfs*16) and a missense variant, p.(Leu2164Pro). We also report additional clinical data on three previously described individuals with a homozygous, loss of function variant, p.(Ser1784*) in INTS1 that shared cognitive delays, cataracts and dysmorphic features with these patients. Several of the variants affected the protein C-terminus and preliminary modeling showed that the p.(Pro1874Leu) and p.(Leu2164Pro) variants may interfere with INTS1 helix folding. In view of the cataracts observed, we performed in-situ hybridization and demonstrated expression of ints1 in the zebrafish eye. We used Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 to make larvae with biallelic insertion/deletion (indel) variants in ints1. The mutant larvae developed typically through gastrulation, but sections of the eye showed abnormal lens development. The distinctive phenotype associated with biallelic variants in INTS1 points to dysfunction of the integrator complex as a mechanism for intellectual disability, eye defects and craniofacial anomalies