Loss of symmetric cell division of apical neural progenitors drives DENND5A-related developmental and epileptic encephalopathy.

Developmental and epileptic encephalopathies (DEEs) are a heterogenous group of epilepsies in which altered brain development leads to developmental delay and seizures, with the epileptic activity further negatively impacting neurodevelopment. Identifying the underlying cause of DEEs is essential for progress toward precision therapies. Here we describe a group of individuals with biallelic variants in DENND5A and determine that variant type is correlated with disease severity. We demonstrate that DENND5A interacts with MUPP1 and PALS1, components of the Crumbs apical polarity complex, which is required for both neural progenitor cell identity and the ability of these stem cells to divide symmetrically. Induced pluripotent stem cells lacking DENND5A fail to undergo symmetric cell division during neural induction and have an inherent propensity to differentiate into neurons, and transgenic DENND5A mice, with phenotypes like the human syndrome, have an increased number of neurons in the adult subventricular zone. Disruption of symmetric cell division following loss of DENND5A results from misalignment of the mitotic spindle in apical neural progenitors. A subset of DENND5A is localized to centrosomes, which define the spindle poles during mitosis. Cells lacking DENND5A orient away from the proliferative apical domain surrounding the ventricles, biasing daughter cells towards a more fate-committed state and ultimately shortening the period of neurogenesis. This study provides a mechanism behind DENND5A-related DEE that may be generalizable to other developmental conditions and provides variant-specific clinical information for physicians and families.

Implementation and evaluation of a shared care model between oncologists and pharmacists for breast cancer patients at a Canadian regional ambulatory cancer centre.

BACKGROUND: The introduction of CDK 4/6 inhibitors for breast cancer patients has contributed to increased ambulatory patient visits for oncologists. The Medication Assessment by Pharmacist program aims to evaluate the impact of oncology pharmacists performing medication assessment follow-up visits. METHODS: Breast cancer patients on a CDK 4/6 inhibitor deemed suitable by their oncologist for pharmacist assessment could be booked for a pharmacist medication assessment appointment at alternate treatment cycles. RESULTS: Between February 2019 to November 2021, 29 of 128 patients (22.7%) were selected for 46 total Medication Assessment by Pharmacist visits resulting in 920 min of clinic time savings for physicians. There were similar rates of adhering to provincial protocols for scheduling visits (99% vs. 96%, p = 0.12) and monitoring investigations (98% vs. 98%, p = 0.96) between those enrolled in Medication Assessment by Pharmacist or not. Surveys completed by medical oncologists and pharmacists demonstrated that nine of nine oncologists felt Medication Assessment by Pharmacist reduced workload and wanted Medication Assessment by Pharmacist expanded to additional oncology drugs. Pharmacist-completed surveys revealed that nine of nine pharmacists felt Medication Assessment by Pharmacist increased job satisfaction, and allowed further application of clinical skills. All agreed that patients were receptive to meeting with pharmacists. According to survey results, 33% of oncologists versus 100% of pharmacists routinely asked about medication adherence, new medications or supplements. CONCLUSION: Integrating pharmacists into a shared care model reduces ambulatory patient visits for oncologists without deviating from provincial protocol guidelines for monitoring and visits for patients on CDK 4/6 inhibitors. Leveraging the medication expertise of pharmacists also increases the frequency of addressing medication adherence and concurrent therapies. Medication Assessment by Pharmacist may be an effective strategy in alleviating projected shortages of oncology providers.

Use of eConsult to enhance genetics service delivery in primary care: A multimethod study.

PURPOSE: Electronic consultation (eConsult) is a freely-available secure online platform connecting primary care providers (PCPs) to geneticists. Our purpose was to determine whether eConsult is effective in improving genetics service delivery in primary care. METHODS: PCP questionnaires regarding eConsult's utility, geneticists' tracking form assessments of eConsult type and appropriateness, and geneticists' interviews on implementing eConsult were carried out. RESULTS: In 2 regions of Ontario, Canada, from January 2019 to June 2020, there were 305 genetics eConsults. For 169 (55%), PCPs indicated receiving good advice for a new course of action; for 110 (36%), referral was now avoided; and for 261 (86%), eConsult was perceived valuable for patient management. Of the 131 geneticist-completed tracking forms, cancer questions were most common (68, 52%). For 63 (48%), geneticists disagreed/strongly disagreed PCPs should know the answer to the referral question. From the interview data, it was observed that geneticists described eConsult positively and suggested how it might improve access and efficiencies if integrated into genetic service delivery. Dealing with eConsults virtually could reduce waitlists, and suggesting appropriate investigations for PCPs could improve efficiencies. CONCLUSION: eConsult offers a potential solution for receiving timely genetics advice and avoiding unnecessary patient referrals, however, greater effect on access and wait times will need systematic integration into PCP and geneticist practice.

Canadian College of Medical Geneticists (CCMG) points to consider: resuming genetic services in a pandemic-a summary.

The COVID-19 pandemic has disrupted the provision of genetic care in Canada. With the public health effort to flatten the curve, many clinics have moved to virtual care for select populations of patients while triaging and postponing others. As genetic services are asked to gradually resume, a roadmap is needed to ensure clinical care decisions for at-risk patients are transparent and equitable, that postponed care is resumed and that patients with or waiting for a genetic diagnosis are not disproportionately affected or abandoned.The purpose of this document is to highlight the guiding ethical principles and stakeholder considerations in resuming genetic services to help guide the competing needs going forward of both limiting exposures while maintaining high-quality care. Considerations highlighted are (1) environment of practice, (2) nature of consult, (3) patient factors, (4) provider factors, and (5) laboratory factors. The intended users are those providing genetic care in a Canadian context with the recognition that there are clinic-specific and regional variations that will influence decision-making. While specific to the Canadian context, the ethical principles used to guide these decisions would be relevant for consideration in other jurisdictions.

Defining and Reporting on Critical Values in Genetics: A Laboratory Survey.

BACKGROUND: Although an obvious critical value in metabolic genetics would be ammonia, it is more challenging to define critical values in molecular genetics and cytogenetics. The objective of this study was to survey genetic laboratories in Ontario, Canada, to determine whether different centers considered similar results as critical and thus potentially deserving of a different reporting process. METHODS: An online 11-question survey was emailed to Ontario laboratory directors, and the results were analyzed. RESULTS: The response rate was 82% (9/11). Cytogenetics and molecular genetics services were each provided by 7 of the 9 centers, with 3 centers providing biochemical/metabolic genetics services and 1 providing maternal marker serum screening services. The case type (e.g., prenatal, newborn, or expedited by the ordering physician) was one factor. Quantitative fluorescence PCR for autosomal aneuploidy, pathogenic variants in both prenatal and postnatal settings, and oncological results were considered critical cytogenetics results. Pathogenic prenatal cases, indeterminate results, and unexpected results were considered more critical for molecular genetics. Critical results were more likely to prompt a telephone call or email to the ordering physician. CONCLUSION: Ontario genetics laboratories tended to have similar reporting processes for critical results. Both the types of cases and the pathogenicity of the result define what values are considered critical.

Cost-effectiveness of genome-wide sequencing for unexplained developmental disabilities and multiple congenital anomalies.

PURPOSE: Genetic testing is routine practice for individuals with unexplained developmental disabilities and multiple congenital anomalies. However, current testing pathways can be costly and time consuming, and the diagnostic yield low. Genome-wide sequencing, including exome sequencing (ES) and genome sequencing (GS), can improve diagnosis, but at a higher cost. This study aimed to assess the cost-effectiveness of genome-wide sequencing in Ontario, Canada. METHODS: A cost-effectiveness analysis was conducted using a discrete event simulation from a public payer perspective. Six strategies involving ES or GS were compared. Outcomes reported were direct medical costs, number of molecular diagnoses, number of positive findings, and number of active treatment changes. RESULTS: If ES was used as a second-tier test (after the current first-tier, chromosomal microarray, fails to provide a diagnosis), it would be less costly and more effective than standard testing (CAN$6357 [95% CI: 6179-6520] vs. CAN$8783 per patient [95% CI: 2309-31,123]). If ES was used after standard testing, it would cost an additional CAN$15,228 to identify the genetic diagnosis for one additional patient compared with standard testing. The results remained robust when parameters and assumptions were varied. CONCLUSION: ES would likely be cost-saving if used earlier in the diagnostic pathway.

New insights into the clinical and molecular spectrum of the novel CYFIP2-related neurodevelopmental disorder and impairment of the WRC-mediated actin dynamics.

PURPOSE: A few de novo missense variants in the cytoplasmic FMRP-interacting protein 2 (CYFIP2) gene have recently been described as a novel cause of severe intellectual disability, seizures, and hypotonia in 18 individuals, with p.Arg87 substitutions in the majority. METHODS: We assembled data from 19 newly identified and all 18 previously published individuals with CYFIP2 variants. By structural modeling and investigation of WAVE-regulatory complex (WRC)-mediated actin polymerization in six patient fibroblast lines we assessed the impact of CYFIP2 variants on the WRC. RESULTS: Sixteen of 19 individuals harbor two previously described and 11 novel (likely) disease-associated missense variants. We report p.Asp724 as second mutational hotspot (4/19 cases). Genotype-phenotype correlation confirms a consistently severe phenotype in p.Arg87 patients but a more variable phenotype in p.Asp724 and other substitutions. Three individuals with milder phenotypes carry putative loss-of-function variants, which remain of unclear pathogenicity. Structural modeling predicted missense variants to disturb interactions within the WRC or impair CYFIP2 stability. Consistent with its role in WRC-mediated actin polymerization we substantiate aberrant regulation of the actin cytoskeleton in patient fibroblasts. CONCLUSION: Our study expands the clinical and molecular spectrum of CYFIP2-related neurodevelopmental disorder and provides evidence for aberrant WRC-mediated actin dynamics as contributing cellular pathomechanism.

A novel DNAH11 variant segregating in a sibship with heterotaxy and implications for genetic counseling.

BACKGROUND: Isomerism or heterotaxy syndrome is the loss of normal asymmetry of the internal thoraco-abdominal organs in the left-right axis and is associated with cardiovascular malformations. Mutations within DNAH11 can be associated with primary ciliary dyskinesia and heterotaxy syndromes. METHODS: We report a family of healthy, nonconsanguinous parents with subsequent pregnancies demonstrating a novel likely pathogenic variant in DNAH11 segregating in a sibship with varied presentations. RESULT: The first affected pregnancy presented with right atrial isomerism. Further DNA testing identified three variants in DNAH11 related to primary ciliary dyskinesia: a maternally inherited heterozygous variant of unknown significance (VUS) c.2772G>A (p.Met924Ile), a maternally inherited novel likely pathogenic variant c.11662C>T (p.Arg3888Cys) as well as a paternally inherited pathogenic c.1648delA variant (p.Arg550GlyfsX16). The second pregnancy inherited the same variants including the pathogenic and likely pathogenic DNAH11 variants and presented with left isomerism and extracardiac abnormalities. CONCLUSION: We present a novel likely pathogenic variant (c.11662C>T) in DNAH11 that has manifested in heterotaxy with variability in phenotypes for subsequent pregnancies of common parents. This report demonstrates that sibship illustrates potential variability in phenotypes associated with the same pathogenic variants within a family and highlights the difficulty in genetic counseling due to the variation in clinical presentation.

Noninvasive Prenatal Testing for Trisomies 21, 18, and 13, Sex Chromosome Aneuploidies, and Microdeletions in Average-Risk Pregnancies: A Cost-Effectiveness Analysis.

OBJECTIVE: The cost effectiveness of noninvasive prenatal testing (NIPT) has been established for high-risk pregnancies but remains unclear for pregnancies at other risk levels. The aim was to assess the cost effectiveness of NIPT in average-risk pregnancies from the perspective of a provincial public payer in Canada. METHODS: A model was developed to compare traditional prenatal screening (TPS), NIPT as a second-tier test (performed only after a positive TPS result), and NIPT as a first-tier test (performed instead of TPS) for trisomies 21, 18, and 13; sex chromosome aneuploidies; and microdeletions in a hypothetical annual population cohort of average-risk pregnancies (142 000 to 148,000) in Ontario, Canada. A probabilistic analysis was conducted with 5000 repetitions. RESULTS: Compared with TPS, NIPT as a second-tier test detected more affected fetuses with trisomies 21, 18, and 13 (188 vs. 158), substantially reduced the number of diagnostic tests (i.e., chorionic villus sampling and amniocentesis) performed (660 vs. 3107), and reduced the cost of prenatal screening ($26.7 million vs. $27.6 million) annually. Compared with second-tier NIPT, first-tier NIPT detected an additional 80 cases of trisomies 21, 18, and 13 at an additional cost of $33 million. The incremental cost per additional affected fetus detected was $412 411. Extending first-tier NIPT to include testing for sex chromosome aneuploidies and 22q11.2 deletion would increase the total screening cost. CONCLUSIONS: NIPT as a second-tier test is cost-saving compared with TPS alone. Compared with second-tier NIPT, first-tier NIPT detects more cases of chromosomal anomalies but at a substantially higher cost.

Activating Mutations of RRAS2 Are a Rare Cause of Noonan Syndrome.

Aberrant signaling through pathways controlling cell response to extracellular stimuli constitutes a central theme in disorders affecting development. Signaling through RAS and the MAPK cascade controls a variety of cell decisions in response to cytokines, hormones, and growth factors, and its upregulation causes Noonan syndrome (NS), a developmental disorder whose major features include a distinctive facies, a wide spectrum of cardiac defects, short stature, variable cognitive impairment, and predisposition to malignancies. NS is genetically heterogeneous, and mutations in more than ten genes have been reported to underlie this disorder. Despite the large number of genes implicated, about 10%-20% of affected individuals with a clinical diagnosis of NS do not have mutations in known RASopathy-associated genes, indicating that additional unidentified genes contribute to the disease, when mutated. By using a mixed strategy of functional candidacy and exome sequencing, we identify RRAS2 as a gene implicated in NS in six unrelated subjects/families. We show that the NS-causing RRAS2 variants affect highly conserved residues localized around the nucleotide binding pocket of the GTPase and are predicted to variably affect diverse aspects of RRAS2 biochemical behavior, including nucleotide binding, GTP hydrolysis, and interaction with effectors. Additionally, all pathogenic variants increase activation of the MAPK cascade and variably impact cell morphology and cytoskeletal rearrangement. Finally, we provide a characterization of the clinical phenotype associated with RRAS2 mutations.

Genetic counselors' preferences for coverage of preimplantation genetic diagnosis: A discrete choice experiment.

Preimplantation genetic diagnosis (PGD) allows couples to test for a genetically affected embryo prior to implantation. Patient access to this ethically complex and expensive technology differs markedly across jurisdictions, with differences in private/public insurance coverage and variations in patient inclusion and diagnostic criteria. The objective of the study was to identify trade-offs regarding PGD coverage decisions amongst genetic counselors. To quantify stated preferences for PGD coverage, we conducted a discrete choice experiment with Canadian genetic counselors (GC) considering attributes regarding the scope of testing (PGD indication, risk of the condition and number of cycles covered) and patient inclusion criteria (fertility status and family history). Multinomial logit regression was used to estimate trade-offs amongst attributes using part-worth utilities and importance scores. The completed response rate was 41% with 126 GC completing the survey. Risk of the genetic condition was the most important attribute. Overall, GC were more responsive to the scope of testing criteria including the condition's risk (importance score of 42%) and PGD indication (31%) rather than family history (11%) and fertility status (8%). Based on this study's attributes and levels, condition characteristics are prioritized even above patient characteristics for PGD coverage.

Challenges in Diagnosing Rare Genetic Causes of Common In Utero Presentations: Report of Two Patients with Mucolipidosis Type II (I-Cell Disease).

Traditional approaches to prenatal genetic diagnosis for common presentations such as short femurs or intrauterine growth restriction are imperfect, and whole-exome sequencing is an emerging option. Mucolipidosis type II (I-cell disease) is an ultra-rare autosomal recessive lysosomal storage disorder with the potential for prenatal-onset skeletal and placental manifestations. We describe the prenatal signs in two recent unrelated patients with confirmed diagnoses soon after birth. In both cases, parents were consanguineous but there was no known family history of mucolipidosis type II. False reassurance was provided after negative testing for another disease with overlapping prenatal manifestations already present in one of the families, emphasizing that offspring of consanguineous parents can be at risk for more than one recessive condition. Our experience illustrates the potential advantages in expanding prenatal applications of WES for the identification of rare single gene disorders in offspring of consanguineous unions.

Molecular characterization of NRXN1 deletions from 19,263 clinical microarray cases identifies exons important for neurodevelopmental disease expression.

PURPOSE: The purpose of the current study was to assess the penetrance of NRXN1 deletions. METHODS: We compared the prevalence and genomic extent of NRXN1 deletions identified among 19,263 clinically referred cases to that of 15,264 controls. The burden of additional clinically relevant copy-number variations (CNVs) was used as a proxy to estimate the relative penetrance of NRXN1 deletions. RESULTS: We identified 41 (0.21%) previously unreported exonic NRXN1 deletions ascertained for developmental delay/intellectual disability that were significantly greater than in controls (odds ratio (OR) = 8.14; 95% confidence interval (CI): 2.91-22.72; P < 0.0001). Ten (22.7%) of these had a second clinically relevant CNV. Subjects with a deletion near the 3' end of NRXN1 were significantly more likely to have a second rare CNV than subjects with a 5' NRXN1 deletion (OR = 7.47; 95% CI: 2.36-23.61; P = 0.0006). The prevalence of intronic NRXN1 deletions was not statistically different between cases and controls (P = 0.618). The majority (63.2%) of intronic NRXN1 deletion cases had a second rare CNV at a prevalence twice as high as that for exonic NRXN1 deletion cases (P = 0.0035). CONCLUSIONS: The results support the importance of exons near the 5' end of NRXN1 in the expression of neurodevelopmental disorders. Intronic NRXN1 deletions do not appear to substantially increase the risk for clinical phenotypes.Genet Med 19 1, 53-61.

Mosaic microdeletion of 17p11.2-p12 and duplication of 17q22-q24 in a girl with Smith-Magenis phenotype and peripheral neuropathy.

We report on a girl with a de novo mosaic derivative chromosome 17 involving a 7.4 Mb deletion of chromosome region 17p11.2 to 17p12 and a duplication of a 12.35 Mb region at 17q22 to 17q24. She was ascertained because of developmental delay, peripheral neuropathy, brachydactyly and minor anomalies. The derivative chromosome was present in approximately 12% of lymphocytes based on FISH studies, and was detected by array comparative genomic hybridization. To our knowledge, this is the third case of mosaicism involving deletion of the 17p11.2 region and the lowest level of mosaicism reported in a patient with Smith-Magenis syndrome (SMS).

Definition of a critical genetic interval related to kidney abnormalities in the Potocki-Lupski syndrome.

Potocki-Lupski syndrome is a genomic disorder caused by duplication of 17p11.2. It is characterized by failure to thrive, intellectual disability, hypotonia, and behavioral difficulties. Structural renal anomalies have been observed in <10% of affected individuals. We present detailed clinical and molecular data on six patients with Potocki-Lupski syndrome, two of whom had renal abnormalities, and investigate the prevalence of kidney abnormalities in the mouse model for the syndrome. In contrast to affected humans, the mouse model does not demonstrate a renal phenotype. Comparison of the duplicated segment in patients with Potocki-Lupski syndrome and the renal phenotype and the syntenic duplicated region in the mouse model allowed us to suggest a 0.285 Mb critical region, including the FLCN gene that may be important for development of renal abnormalities in patients with this duplication.

Extracellular matrix and platelet function in patients with musculocontractural Ehlers-Danlos syndrome caused by mutations in the CHST14 gene.

We report on a consanguineous, Afghani family with two sisters affected with characteristic facial features, multiple contractures, progressive joint and skin laxity, hemorrhagic diathesis following minor trauma and multisystem fragility-related manifestations suggestive of a diagnosis of musculocontractural Ehlers-Danlos syndrome (EDS). This novel form of connective tissue disorder was recently reported in patients of Japanese, Turkish, and Indian descent who were formerly classified as having EDS type VIB and has now been recognized to be a part of spectrum including patients previously classified as having adducted thumb-clubfoot syndrome. We identified a previously unreported mutation in the CHST14 gene, which codes for the enzyme dermatan 4-O-sulfotransferase. We discuss the prenatal presentation, detailed clinical manifestations, and neurological findings in two sisters with this newly described musculocontractural EDS-CHST14 type. We demonstrate that fibroblasts from one of our patients produce more chondroitin sulfate than normal and show lower than normal deposition of collagens I and II and fibrillin 1-containing microfibrills. These findings suggest that the imbalance in the glycosaminoglycan content in developing tissues might interfere with normal deposition of other extracellular matrix components and ultimately contribute to the development of the phenotype observed in these patients. Furthermore, we ruled out the contribution of intrinsic platelet factors to the bleeding diathesis observed in some affected individuals.

The Roberts syndrome/SC phocomelia spectrum--a case report of an adult with review of the literature.

Roberts syndrome (RBS) (OMIM #268300) is a rare autosomal recessive disorder characterized by tetraphocomelia (symmetrical limb reduction), craniofacial anomalies, growth retardation, mental retardation, cardiac and renal abnormalities. The syndrome is caused by mutations in the ESCO2 (establishment of cohesion 1 homolog 2) (Entrez 609353) gene, which is located at 8p21.1, and encodes a protein essential in establishing sister chromatid cohesion during S phase. SC phocomelia (SC) (OMIM #269000), has less severe symmetric limb reduction, flexion contractures of various joints, minor facial anomalies, growth retardation and occasionally, mental retardation. These two syndromes can be considered part of a spectrum, with RBS at the most severe range in which severely affected infants may be stillborn or die in the post-natal period, while individuals with SC phocomelia represent the milder end of the spectrum and typically survive to adulthood. In both presentations, karyotype investigations characteristically reveal premature centromere separation (PCS), otherwise known as heterochromatin repulsion or puffing. There is little literature about the follow-up of adults with the spectrum of RBS/SC phocomelia or their recommended management. We report on an adult presentation of RBS/SC phocomelia spectrum disorder with a history of major cardiac malformation in childhood, normal limbs on physical examination, mild facial anomalies, mild learning difficulties, and PCS. Molecular studies of ESCO2 have confirmed the diagnosis. A literature review, focussing on adult manifestations of this condition and a discussion of follow-up guidelines are presented.