Sirenomelia: An anatomical assessment and genetic sex determination of two cases.

The etiology of sirenomelia is currently unknown. Data are limited in comparing external and internal abnormalities using modern imaging technologies and molecular genetic analysis. The purpose of the current study was designed to compare external and internal anatomical defects in two cases of sirenomelia and Potter's sequence. Considered rare, Potter's sequence is a fetal disorder with characteristic features of bilateral renal agenesis, obstructive uropathy, atypical facial appearance, and limb malformations. The internal and external malformations of two term fetuses with sirenomelia and Potter's sequence were compared using assessment of external features, radiography and MRI on internal structures, and molecular genetic studies on sex determination. Data reveal that both fetuses were male and manifested with an overlapping but distinct spectrum of abnormalities. Principal differences were noted in the development of the ears, brain, urogenital system, lower limbs, pelvis, and vertebral column. Defects of the axial mesoderm are likely to underlie the abnormalities seen in both fetuses. The first one, which had only caudal defects, was found to have a spectrum of abnormalities most similar to those associated with more severe forms of the small pelvic outlet syndrome, although the structure and orientation of the sacrum and iliae were different from previously reported cases. The other had both caudal and cranial defects, and was most similar to those described in the axial mesodermal dysplasia syndrome. Defects associated with sirenomelia can be evaluated with standard gross anatomy examination, radiology, MRI, and modified PCR techniques to determine anatomical abnormalities and the sex of preserved specimens, respectively. Evidence indicated that sirenomelia could be developed via various etiologies.

Families' healthcare experiences for children with inherited metabolic diseases: protocol for a mixed methods cohort study.

INTRODUCTION: Children with inherited metabolic diseases (IMDs) often have complex and intensive healthcare needs and their families face challenges in receiving high-quality, family centred health services. Improvement in care requires complex interventions involving multiple components and stakeholders, customised to specific care contexts. This study aims to comprehensively understand the healthcare experiences of children with IMDs and their families across Canada. METHODS AND ANALYSIS: A two-stage explanatory sequential mixed methods design will be used. Stage 1: quantitative data on healthcare networks and encounter experiences will be collected from 100 parent/guardians through a care map, 2 baseline questionnaires and 17 weekly diaries over 5-7 months. Care networks will be analysed using social network analysis. Relationships between demographic or clinical variables and ratings of healthcare experiences across a range of family centred care dimensions will be analysed using generalised linear regression. Other quantitative data related to family experiences and healthcare experiences will be summarised descriptively. Ongoing analysis of quantitative data and purposive, maximum variation sampling will inform sample selection for stage 2: a subset of stage 1 participants will participate in one-on-one videoconference interviews to elaborate on the quantitative data regarding care networks and healthcare experiences. Interview data will be analysed thematically. Qualitative and quantitative data will be merged during analysis to arrive at an enhanced understanding of care experiences. Quantitative and qualitative data will be combined and presented narratively using a weaving approach (jointly on a theme-by-theme basis) and visually in a side-by-side joint display. ETHICS AND DISSEMINATION: The study protocol and procedures were approved by the Children's Hospital of Eastern Ontario's Research Ethics Board, the University of Ottawa Research Ethics Board and the research ethics boards of each participating study centre. Findings will be published in peer-reviewed journals and presented at scientific conferences.

Pathogenic SPTBN1 variants cause an autosomal dominant neurodevelopmental syndrome.

SPTBN1 encodes ßII-spectrin, the ubiquitously expressed ß-spectrin that forms micrometer-scale networks associated with plasma membranes. Mice deficient in neuronal ßII-spectrin have defects in cortical organization, developmental delay and behavioral deficiencies. These phenotypes, while less severe, are observed in haploinsufficient animals, suggesting that individuals carrying heterozygous SPTBN1 variants may also show measurable compromise of neural development and function. Here we identify heterozygous SPTBN1 variants in 29 individuals with developmental, language and motor delays; mild to severe intellectual disability; autistic features; seizures; behavioral and movement abnormalities; hypotonia; and variable dysmorphic facial features. We show that these SPTBN1 variants lead to effects that affect ßII-spectrin stability, disrupt binding to key molecular partners, and disturb cytoskeleton organization and dynamics. Our studies define SPTBN1 variants as the genetic basis of a neurodevelopmental syndrome, expand the set of spectrinopathies affecting the brain and underscore the critical role of ßII-spectrin in the central nervous system.

SPEN haploinsufficiency causes a neurodevelopmental disorder overlapping proximal 1p36 deletion syndrome with an episignature of X chromosomes in females.

Deletion 1p36 (del1p36) syndrome is the most common human disorder resulting from a terminal autosomal deletion. This condition is molecularly and clinically heterogeneous. Deletions involving two non-overlapping regions, known as the distal (telomeric) and proximal (centromeric) critical regions, are sufficient to cause the majority of the recurrent clinical features, although with different facial features and dysmorphisms. SPEN encodes a transcriptional repressor commonly deleted in proximal del1p36 syndrome and is located centromeric to the proximal 1p36 critical region. Here, we used clinical data from 34 individuals with truncating variants in SPEN to define a neurodevelopmental disorder presenting with features that overlap considerably with those of proximal del1p36 syndrome. The clinical profile of this disease includes developmental delay/intellectual disability, autism spectrum disorder, anxiety, aggressive behavior, attention deficit disorder, hypotonia, brain and spine anomalies, congenital heart defects, high/narrow palate, facial dysmorphisms, and obesity/increased BMI, especially in females. SPEN also emerges as a relevant gene for del1p36 syndrome by co-expression analyses. Finally, we show that haploinsufficiency of SPEN is associated with a distinctive DNA methylation episignature of the X chromosome in affected females, providing further evidence of a specific contribution of the protein to the epigenetic control of this chromosome, and a paradigm of an X chromosome-specific episignature that classifies syndromic traits. We conclude that SPEN is required for multiple developmental processes and SPEN haploinsufficiency is a major contributor to a disorder associated with deletions centromeric to the previously established 1p36 critical regions.

Parkinsonism in Patients with Neuronopathic (Type 3) Gaucher Disease: A Case Series.

BACKGROUND: The link between Parkinson's disease (PD), the second most common neurodegenerative disorder, and nonneuronopathic Gaucher disease (GD) is well established. Currently, PD is primarily associated with nonneuronopathic GD; however, with currently available treatments, patients with chronic neuronopathic GD, who historically had a shortened life span, are now living well into their 50s and beyond. CASES: We highlight 4 patients with chronic neuronopathic GD with parkinsonian features, describing their GD genotype and phenotype as well as the presentation and progression of their parkinsonism. Symptoms presented in their fourth or fifth decade of life, and include unilateral bradykinesia and/or tremor. Of the patients, 3 had cognitive impairment. The fourth patient has not shown cognitive decline 6 years after PD onset. CONCLUSION: This small series highlights that PD is not exclusively associated with nonneuronopathic GD and that as the chronic neuronopathic GD population ages, the clinical spectrum and heterogeneity of neurological manifestations may include parkinsonism.

A dominant autoinflammatory disease caused by non-cleavable variants of RIPK1.

Activation of RIPK1 controls TNF-mediated apoptosis, necroptosis and inflammatory pathways1. Cleavage of human and mouse RIPK1 after residues D324 and D325, respectively, by caspase-8 separates the RIPK1 kinase domain from the intermediate and death domains. The D325A mutation in mouse RIPK1 leads to embryonic lethality during mouse development2,3. However, the functional importance of blocking caspase-8-mediated cleavage of RIPK1 on RIPK1 activation in humans is unknown. Here we identify two families with variants in RIPK1 (D324V and D324H) that lead to distinct symptoms of recurrent fevers and lymphadenopathy in an autosomal-dominant manner. Impaired cleavage of RIPK1 D324 variants by caspase-8 sensitized patients' peripheral blood mononuclear cells to RIPK1 activation, apoptosis and necroptosis induced by TNF. The patients showed strong RIPK1-dependent activation of inflammatory signalling pathways and overproduction of inflammatory cytokines and chemokines compared with unaffected controls. Furthermore, we show that expression of the RIPK1 mutants D325V or D325H in mouse embryonic fibroblasts confers not only increased sensitivity to RIPK1 activation-mediated apoptosis and necroptosis, but also induction of pro-inflammatory cytokines such as IL-6 and TNF. By contrast, patient-derived fibroblasts showed reduced expression of RIPK1 and downregulated production of reactive oxygen species, resulting in resistance to necroptosis and ferroptosis. Together, these data suggest that human non-cleavable RIPK1 variants promote activation of RIPK1, and lead to an autoinflammatory disease characterized by hypersensitivity to apoptosis and necroptosis and increased inflammatory response in peripheral blood mononuclear cells, as well as a compensatory mechanism to protect against several pro-death stimuli in fibroblasts.

Bridging the gap in genetics: a progressive model for primary to specialist care.

BACKGROUND: The rapid expansion of genetic knowledge, and the implications for healthcare has resulted in an increased role for Primary Care Providers (PCPs) to incorporate genetics into their daily practice. The objective of this study was to explore the self-identified needs, including educational needs, of both urban and rural Primary Care Providers (PCPs) in order to provide genetic care to their patients. METHODS: Using a qualitative grounded theory approach, ten key informant interviews, and one urban and two rural PCP focus groups (FGs) (n = 19) were conducted. All PCPs practiced in Southeastern Ontario. Data was analyzed using a constant comparative method and thematic design. The data reported here represent a subset of a larger study. RESULTS: Participants reported that PCPs have a responsibility to ensure patients receive genetic care. However, specific roles and responsibilities for that care were poorly defined. PCPs identified a need for further education and resources to enable them to provide care for individuals with genetic conditions. Based on the findings, a progressive stepped model that bridges primary and specialty genetic care was developed; the model ranged from PCPs identifying patients with genetic conditions that they could manage alone, to patients who they could manage with informal or electronic consultation to those who clearly required specialist referral. CONCLUSIONS: PCPs identified a need to integrate genetics into primary care practice but they perceived barriers including a lack of knowledge and confidence, access to timely formal and informal consultation and clearly defined roles for themselves and specialists. To address gaps in PCP confidence in providing genetic care, interventions that are directed at accessible just-in-time support and consultation have the potential to empower PCPs to manage patients' genetic conditions. Specific attention to content, timing, and accessibility of educational interventions is critical to address the needs of both urban and rural PCPs. A progressive framework for bridging primary to specialty care through a 'stepped' model for providing continuing medical education, and genetic care can was developed and can be used to guide future design and delivery of educational interventions and resources.

Student Reflections on the Queen's Accelerated Route to Medical School Programme.

CONTEXT: Since its inception more than 150 years ago, the School of Medicine at Queen's University has aspired 'to advance the tradition of preparing excellent physicians and leaders in health care by embracing a spirit of inquiry and innovation in education and research'. As part of this continuing commitment, Queen's School of Medicine developed the Queen's University Accelerated Route to Medical School (QuARMS). As Canada's only 2-year accelerated-entry premedical programme, QuARMS was designed to reduce training time, the associated expense of medical training, and to encourage a collaborative premedical experience. Students enter QuARMS directly from high school and then spend 2 years enrolled in an undergraduate degree programme. They then are eligible to enter the first-year MD curriculum. The 2-year QuARMS academic curriculum includes traditional undergraduate coursework, small group sessions, and independent activities. The QuARMS curriculum is built on 4 pillars: communication skills, critical thinking, the role of physician (including community service learning [CSL]), and scientific foundations. Self-regulated learning (SRL) is explicitly developed throughout all aspects of the curriculum. Medical educators have defined SRL as the cyclical control of academic and clinical performance through several key processes that include goal-directed behaviour, use of specific strategies to attain goals, and the adaptation and modification to behaviours or strategies that optimize learning and performance. Based on Zimmerman's social cognitive framework, this definition includes relationships among the individual, his or her behaviour, and the environment, with the expectation that individuals will monitor and adjust their behaviours to influence future outcomes. OBJECTIVES: This study evaluated the students' learning as perceived by them at the conclusion of their first 2 academic years. METHODS: At the end of the QuARMS learning stream, the first and second cohorts of students completed a 26-item, 4-point Likert-type instrument with space for optional narrative details for each question. A focus group with each group explored emergent issues. Consent was obtained from 9 out of 10 and 7 out of 8 participants to report the 2015 survey and focus group data, respectively, and from 10 out of 10 and 9 out of 10 participants to report the 2016 survey and focus group data, respectively. Thematic analysis and a constructivist interpretive paradigm were used. A distanced facilitator, standard protocols, and a dual approach assured consistency and trustworthiness of data. RESULTS: Both analyses were congruent. Students described experiences consistent with curricular goals including critical thinking, communication, role of a physician, CSL, and SRL. Needs included additional mentorship, more structure for CSL, more feedback, explicit continuity between in-class sessions, and more clinical experience. Expectations of students towards engaging in independent learning led to some feelings of disconnectedness. CONCLUSIONS: Participants described benefit from the sessions and an experience consistent with the curricular goals, which were intentionally focused on foundational skills. In contrast to the goal of SRL, students described a need for an explicit educational structure. Thus, scaffolding of the curriculum from more structured in year 1 to less structured in year 2 using additional mentorship and feedback is planned for subsequent years. Added clinical exposure may increase relevance but poses challenges for integration with the first-year medical class.

Primary care providers' lived experiences of genetics in practice.

To effectively translate genetic advances into practice, engagement of primary care providers (PCPs) is essential. Using a qualitative, phenomenological methodology, we analyzed key informant interviews and focus groups designed to explore perspectives of urban and rural PCPs. PCPs endorsed a responsibility to integrate genetics into their practices and expected advances in genetic medicine to expand. However, PCPs reported limited knowledge and difficulties accessing resources, experts, and continuing education. Rural practitioners' additional concerns included cost, distance, and poor patient engagement. PCPs' perspectives are crucial to develop relevant educational and systems-based interventions to further expand genetic medicine in primary care.

Computational Prediction of Position Effects of Apparently Balanced Human Chromosomal Rearrangements.

Interpretation of variants of uncertain significance, especially chromosomal rearrangements in non-coding regions of the human genome, remains one of the biggest challenges in modern molecular diagnosis. To improve our understanding and interpretation of such variants, we used high-resolution three-dimensional chromosomal structural data and transcriptional regulatory information to predict position effects and their association with pathogenic phenotypes in 17 subjects with apparently balanced chromosomal abnormalities. We found that the rearrangements predict disruption of long-range chromatin interactions between several enhancers and genes whose annotated clinical features are strongly associated with the subjects' phenotypes. We confirm gene-expression changes for a couple of candidate genes to exemplify the utility of our analysis of position effect. These results highlight the important interplay between chromosomal structure and disease and demonstrate the need to utilize chromatin conformational data for the prediction of position effects in the clinical interpretation of non-coding chromosomal rearrangements.

Mutations in the Chromatin Regulator Gene BRPF1 Cause Syndromic Intellectual Disability and Deficient Histone Acetylation.

Identification of over 500 epigenetic regulators in humans raises an interesting question regarding how chromatin dysregulation contributes to different diseases. Bromodomain and PHD finger-containing protein 1 (BRPF1) is a multivalent chromatin regulator possessing three histone-binding domains, one non-specific DNA-binding module, and several motifs for interacting with and activating three lysine acetyltransferases. Genetic analyses of fish brpf1 and mouse Brpf1 have uncovered an important role in skeletal, hematopoietic, and brain development, but it remains unclear how BRPF1 is linked to human development and disease. Here, we describe an intellectual disability disorder in ten individuals with inherited or de novo monoallelic BRPF1 mutations. Symptoms include infantile hypotonia, global developmental delay, intellectual disability, expressive language impairment, and facial dysmorphisms. Central nervous system and spinal abnormalities are also seen in some individuals. These clinical features overlap with but are not identical to those reported for persons with KAT6A or KAT6B mutations, suggesting that BRPF1 targets these two acetyltransferases and additional partners in humans. Functional assays showed that the resulting BRPF1 variants are pathogenic and impair acetylation of histone H3 at lysine 23, an abundant but poorly characterized epigenetic mark. We also found a similar deficiency in different lines of Brpf1-knockout mice. These data indicate that aberrations in the chromatin regulator gene BRPF1 cause histone H3 acetylation deficiency and a previously unrecognized intellectual disability syndrome.

Parents' Understanding of Genetics and Heritability.

Parents have the opportunity to educate their children to facilitate behaviours and lifestyle habits that may prevent or delay genetic disease, or mitigate predispositions within the family. We sought to determine parents' understanding of genetic knowledge and heritability. Using a quantitative survey methodology 108 volunteer participants were surveyed from a convenience sample of all parents/caregivers within the waiting room of a general children's outpatient clinic. Results indicated that average genetic knowledge levels were fairly high, with the majority of participants scoring 70-80 % correct on knowledge-based questions. Further, scores were found to be positively correlated with education, but inversely correlated with self-perceived knowledge. This finding suggests that participants with less experience tended to overestimate their knowledge. We suggest that gaps in knowledge of genetics and heritability could be improved by using educational interventions such as media campaigns, provision of informational brochures, or changes to current high school curriculum which would increase exposure to genetics and heritability for both parents and children.

Melanocortin-4 Receptor Deficiency Phenotype with an Interstitial 18q Deletion: A Case Report of Severe Childhood Obesity and Tall Stature.

Childhood obesity is a growing health concern, associated with significant physical and psychological morbidity. Childhood obesity is known to have a strong genetic component, with mutations in the melanocortin-4 receptor (MC4R) gene being the most common monogenetic cause of obesity. Over 166 different MC4R mutations have been identified in persons with hyperphagia, severe childhood obesity, and increased linear growth. However, it is unclear whether the MC4-R deficiency phenotype is due to haploinsufficiency or dominant-negative effects by the mutant receptor. We report the case of a four-and-a-half-year-old boy with an interstitial deletion involving the long arm of chromosome 18 (46,XY,del(18)(q21.32q22.1)) encompassing the MC4R gene. This patient presented with tall stature and hyperphagia within his first 18 months of life leading to significant obesity. This case supports haploinsufficiency of MC4-R as it describes a MC4-R deficiency phenotype in a patient heterozygous for a full MC4R gene deletion. The intact functional allele with MC4-R haploinsufficiency has the potential to favor a therapeutic response to gastric surgery. Currently, small molecule MC4-R agonists are under development for pharmacologic therapy.

Congenital myopathy with cap-like structures and nemaline rods: case report and literature review.

BACKGROUND: Cap myopathy is a rare congenital myopathy characterized by cap structures located at the periphery of the muscle fiber. Cap structures consist of disarranged thin filaments with enlarged Z discs. The clinical presentation and natural history of cap myopathy is variable and overlaps with other congenital myopathies. METHODS: We describe a 10-year-old boy with cap myopathy and contrast him with 20 other individuals reported in the literature. RESULTS: Our patient presented at birth with hypotonia and weakness and subsequently developed respiratory failure in infancy. He is ambulatory but has increasing fatigue and requires a wheelchair by midafternoon. His muscle biopsy at 3 months revealed a nemaline myopathy and secondary fiber-type disproportion with type 1 hypotrophy and predominance. A repeat muscle biopsy at age 6 years revealed numerous peripherally located cap-like structures containing nemaline rods and exhibited a spectrum of Z-disk and myofibrillar abnormalities. Molecular genetic testing was performed for NEB, TPM2, TPM3, ACTA1, TNNT1, SEPN1, SMN1, DMPK, FSHMD1A, and mtDNA. A known pathogenic mutation, c.1152+1G>A, and a previously unreported variant, c.1782+4_1782+5delAG, were detected in NEB. CONCLUSION: Our patient has a more severe phenotype than most reported patients and is the first patient with cap myopathy to have a mutation in NEB. Our case supports the identification of cap myopathy as a congenital myopathy with significant overlapping features with nemaline myopathies and further elucidates the phenotype of this disease.

X-linked deafness-2 (DFNX2) phenotype associated with a paracentric inversion upstream of POU3F4.

PURPOSE: The authors report on a 7-year-old male, designated FR, who has severe sensorineural hearing loss. Features include a round face, hypertelorism, epicanthal folds, and flat nasal root. Although there were early developmental concerns regarding FR, all but his speech delay resolved when he was placed in an educational program that accommodated his hearing loss. Genetic studies were performed to investigate genetic causes for his hearing loss. METHOD: History, physical examination, audiologic assessment, and imaging were performed according to usual practice. FMR1,GJB2,GJB6, and POU3F4 genes were sequenced. Chromosomal studies consisted of karyotyping and breakpoint analysis by fluorescence in situ hybridization (FISH). RESULTS: Results from FMR1,GJB2,GJB6, and POU3F4 sequencing and echocardiography, electrocardiogram, and abdominal ultrasound were normal. A computed tomography (CT) scan revealed a large fundus of the internal auditory canals and absence of the bony partition between the fundus and the adjacent cochlear turns, with a widened modiolus bilaterally. FR's CT findings were consistent with those described in persons with X-linked deafness-2 (DFNX2) hereditary deafness. FR's karyotype was 46,inv(X)(q13q24),Y.ish inv(X)(XIST+)mat. FISH refined the breakpoints to inv(X)(q21.1q22.3). The Xq21.1 breakpoint was narrowed to a 25-kb region 450 kb centromeric to the DFNX2 gene, POU3F4. There are rare case reports of DFNX2 patients with chromosomal rearrangements positioned centromeric to POU3F4 and no mutations within the gene. CONCLUSION: Authors hypothesized that FR's hearing loss was caused by dysregulation of POU3F4 due to separation from regulatory elements affected by the inversion.

Gaucher disease associated with parkinsonism: four further case reports.

Type 1 Gaucher disease is considered the non-neuronopathic form of this autosomal recessively inherited lysosomal storage disease. We report the simultaneous occurrence of Gaucher disease with parkinsonian in four adult patients. The patients had a relatively early onset of parkinsonian manifestations, and their disease was rapidly progressive and refractory to therapy. Each had a different Gaucher genotype, although four alleles carried the common N370S mutation. No mutations were identified in the genes for parkin or alpha-synuclein. The concurrence of these two phenotypes, both in this series of patients and in others in the literature, suggests a shared pathway, modifier, or other genetic etiology.