Genomic sequencing (GS) for patients and families with rare disease creates the opportunity for precise diagnosis as well as the option to learn about medically actionable secondary findings (SF). Debate persists internationally on how to manage the analysis and disclosure of SF, especially in settings where service delivery models for GS are still in development and outcomes are preliminary. This study aimed to understand parents' decision to opt-out of learning about their child's SF for adult-onset conditions and whether an SF identified in a child was inherited. All children received GS as part of their diagnostic work-up for a rare disease. Sixteen semistructured interviews were conducted with parents. Guided by a qualitative approach, interviews were analyzed with inductive content analysis. Participants reported that the timing of decision-making, competing priorities, anticipated adverse psychological outcomes, and health-related beliefs and worldviews contributed to their decision to opt-out of receiving SF. An emphasis was placed on a preference for flexible SF delivery models to aid in reducing the burden of SF decision-making at the time of indication-based testing. Genetic service delivery models that separate the timing of decisions about indication-based test results and SF may address patient preferences. Findings from this work may inform clinical practice and policy in jurisdictions where SF delivery models are still being developed and optimized.

Genetic testing by primary care pediatricians is becoming more commonplace for individuals with autism spectrum disorder (ASD), however lengthy waiting times for a genetics assessment remains a barrier. Identifying whether ASD in a child is 'non-syndromic' [isolated] or 'ASD plus' can help inform medical management and recurrence risk. Given the long wait times to see a clinical geneticist at our center (MD only), we developed a Genetic Counselor first clinic (GC only) where after review of referrals with a geneticist, children with suspected isolated ASD and a variant of uncertain clinical significance (VUS) on chromosomal microarray saw a GC only.

Genome-wide Sequencing (GWS) allows for identification of disease-causing genetic variants and may reveal secondary findings (SF). SF are variants in genes unrelated to the initial indication for testing but are associated with risk for other medically actionable conditions and are becoming more commonly offered in clinical practice. Genome-wide Sequencing Ontario (GSO), a GWS service in Ontario, Canada, reports SF associated with actionability in childhood for all pediatric patients, with optional reporting for those actionable in adulthood.

CYP26B1 metabolizes retinoic acid in the developing embryo to regulate its levels. A limited number of individuals with pathogenic variants in CYP26B1 have been documented with a varied phenotypic spectrum, spanning from a severe manifestation involving skull anomalies, craniosynostosis, encephalocele, radio-humeral fusion, oligodactyly, and a narrow thorax, to a milder presentation characterized by craniosynostosis, restricted radio-humeral joint mobility, hearing loss, and intellectual disability. Here, we report two families with CYP26B1 -related phenotypes and describe the data obtained from functional studies of the variants. Exome and Sanger sequencing were used for variant identification in family 1 and family 2, respectively. Family 1 reflects a mild phenotype, which includes craniofacial dysmorphism with brachycephaly (without craniosynostosis), arachnodactyly, reduced radioulnar joint movement, conductive hearing loss, learning disability—and compound heterozygous CYP26B1 variants: (p.[(Pro118Leu)];[(Arg234Gln)]) were found. In family 2, a stillborn fetus presented a lethal phenotype with spina bifida occulta, hydrocephalus, poor skeletal mineralization, synostosis, limb defects, and a synonymous homozygous variant in CYP26B1 : c.1083C > A. A minigene assay revealed that the synonymous variant created a new splice site, removing part of exon 5 (p.Val361_Asp382del). Enzymatic activity was assessed using a luciferase assay, demonstrating a notable reduction in exogenous retinoic acid metabolism for the variant p.Val361_Asp382del. (~ 3.5 × decrease compared to wild-type); comparatively, the variants p.(Pro118Leu) and p.(Arg234Gln) demonstrated a partial loss of metabolism (1.7× and 2.3× reduction, respectively). A proximity-dependent biotin identification assay reaffirmed previously reported ER-resident protein interactions. Additional work into these interactions is critical to determine if CYP26B1 is involved with other biological events on the ER. Immunofluorescence assay suggests that mutant CYP26B1 is still localized in the endoplasmic reticulum. These results indicate that novel pathogenic variants in CYP26B1 result in varying levels of enzymatic activity that impact retinoic acid metabolism and relate to the distinct phenotypes observed.

The goal of this study was to identify potential barriers in applying to a genetic counseling (GC) Master's degree program to inform strategies for increasing diversity and inclusiveness in the GC student recruitment process. Participants included prospective GC program applicants and admissions committee members from the four Canadian accredited programs. The study was conducted using a quantitative survey-based approach. Twenty-five prospective applicants who previously applied to a GC Master's degree program, 26 who had not applied, and 48 admissions committee members completed the survey. The small number of positions in GC programs was perceived by all groups as highly likely to impact an applicant's ability to gain acceptance to a program as was the limited number of GC training programs. Prospective applicants perceived additional barriers as significantly more likely to impact an individual's ability to apply to/attend a program when compared with admissions committee members including: cost of the application process, the applicant being a visible minority and the applicant having a physical disability. These findings highlight a number of perceived barriers related to applying to a GC Master's degree program. To our knowledge, this is the first study surveying prospective applicants and admissions committee members on barriers faced during the application process. The data from this study can also be used to inform the application process for other health professions.

Objective: To survey genetic counselors (GCs) who have counseled about mosaic embryos regarding the challenges they faced in counseling this patient population and assess their need for more resources to support their practice. Design: Self-administered online survey. Setting: Academic university. Study Population: Seventy-eight GCs primarily from the United States and Canada. Intervention(s): Genetic counselors completed a quantitative survey with an embedded qualitative component. Quantitative data were analyzed by descriptive statistics. An inductive thematic analysis was performed on open-text responses. Main Outcome Measure(s): Genetic counselors were asked what clinical activities relating to mosaic embryos they performed. They were then asked to rate how challenging each activity was to perform using a 5-point scale; a rating of 4 or 5 was defined as highly challenging. Open-text questions enabled GCs to describe factors that they felt contributed to these challenges. Result(s): The challenges reported by GCs included the uncertainty of outcomes in offspring after mosaic embryo transfer, limited guidelines available to assist clinicians with counseling about mosaic embryos, and ranking mosaic embryos by suitability for transfer. The contributing factors suggested by participants included limited outcome data, limited GC involvement in pretest counseling for preimplantation genetic testing for aneuploidy (PGT-A), and perceived inconsistency in counseling practices across clinics. Genetic counselors differed in their genetic testing recommendations for pregnancies conceived after mosaic embryo transfer. Amniocentesis and postnatal assessment were recommended by 85% and 49% of GCs, respectively, and 15% recommended chorionic villus sampling and noninvasive prenatal testing. Almost all (92%) reported a need for more resources, such as standardized guidelines, more outcome data, and continuing education on PGT-A and mosaicism. Conclusion(s): This study describes challenges experienced by GCs while they counseled about mosaic embryos. Our findings demonstrate a need for more outcome data on mosaic embryo pregnancies and for evidence-based clinical guidelines. The differing recommendations for prenatal genetic testing among GCs in the study warrant further research into contributing factors. We strongly recommend that pretest counseling, including a discussion regarding mosaicism, is provided to all couples considering PGT-A to reduce counseling challenges and to promote patients’ informed decision-making.

45,X/46,XY chromosomal mosaicism presents a range of clinical manifestations, including phenotypes from Turner syndrome through genital abnormalities to apparently unaffected phenotypic males; however, the full clinical spectrum has not yet been fully delineated since prior studies on the clinical phenotype and associated risk of gonadal tumors included small cohorts and limited follow-up. To better describe the clinical manifestations and long-term outcome of patients with 45,X/46,XY mosaicism. We conducted a retrospective chart review of patients with 45,X/46,XY from three health centers (Hospital for Sick Children and Mount Sinai Hospital in Canada, and University of Pittsburgh Medical Center in United States). Of 100 patients with 45,X/46,XY karyotype, 47 were raised as females and 53 as males. Females were significantly shorter than males (p = 0.04) and height Z-score was significantly decreased with age for both genders (p = 0.02). Growth hormone (GH) treatment did not result in a significant height increase compared to the untreated group (p = 0.5). All females required puberty induction in contrast to majority of males. Five females were diagnosed with gonadal tumors, while no males were affected. Around 58% of patients exhibited at least one Turner syndrome stigmata. This study expands the clinical spectrum, long-term outcomes, and associated tumor risk in a large cohort of patients with 45,X/46,XY mosaicism. Additionally, it highlights our experience with GH therapy and prophylactic gonadectomy.

The use of next-generation sequencing technologies such as genomic sequencing in newborn screening (NBS) could enable the detection of a broader range of conditions. We explored parental preferences and attitudes towards screening for conditions for which varying types of treatment exist with a cross-sectional survey completed by 100 parents of newborns who received NBS in Ontario, Canada. The survey included four vignettes illustrative of hypothetical screening targets, followed by questions assessing parental attitudes. Chi-square tests were used to compare frequency distributions of preferences. Results show that most parents supported NBS for conditions for which only supportive interventions are available, but to a significantly lesser degree than those with disease-specific treatments (99% vs. 82–87%, p ≤ 0.01). For conditions without an effective treatment, the type of supportive care and age of onset of the condition did not significantly alter parent perceptions of risks and benefits. Parents are interested in expanded NBS for conditions with only supportive interventions in childhood, despite lower levels of perceived benefit for the child and greater anticipated anxiety from screen-positive results. These preferences suggest that the expansion of NBS may require ongoing deliberation of perceived benefits and risks and enhanced approaches to education, consent, and support.

Of the couples trying to conceive (had frequent, unprotected sexual intercourse for a year or longer) 15% will experience infertility with the annual incidence of infertility estimated at 1.2 couples per 1,000 total in the general population. Male factors contribute to over 50% of the cases with 7% of the male population experiencing infertility. Not being able to conceive a child is emotionally traumatic and frustrating and can affect the person’s self esteem and the couple’s relationship. Major progress has been achieved in identifying the etiology of male infertility and especially the genetic causes. However, in about 40% of the male infertility cases, the etiology remains unknown and both the diagnosis and/or treatment are a challenge. Genetic testing to determine the underlying genetic cause of infertility is not 100% and genes involved are still being discovered. Consequently, negative genetic test results do not rule out a genetic cause. Thus, genetic counselling should include information regarding the genetic etiology, if known, and the treatment options available. Furthermore, when the infertile couple/male is seeking assisted reproductive technology (ART) using intracytoplasmic sperm injection (ICSI), genetic counselling should include information regarding the risk of transmitting the genetic disorder, causing the male infertility, to the offspring. Therefore, the provision of genetic counselling is an integral component in the investigation and treatment of male infertility. This article will discuss the genetic counselling approach in cases with male infertility.

The birth of a baby with atypical external and/or internal genitalia is a family crisis that requires the interaction between multidisciplinary group physicians including pediatric urologists, pediatric endocrinologists, medical geneticists, genetic counsellors, gynecologists, psychologists/psychiatrists and social workers with expertise in this field. Following each of the specialists’ assessment the findings, plan for investigations, the psychosocial situation and gender assignment and treatment should be reviewed among the group members prior to meeting the family. Following the group discussion the information should be presented to the parents using easy to understand language with visual aids and their questions should be answered so that they can make an informed decision regarding gender assignment, surgical options, where medically indicated, and hormone treatment. Potential for sexual relationships and fertility preservation should be discussed. The birth of a baby with abnormalities may be associated with mother/parental guilt feeling and the point that there is nothing that they did or did not do that caused the newborn’s condition. Disorder of sex development (DSD) can be divided into isolated and non-isolated according to the finding on physical examination and should be further classified into abnormalities of chromosomal abnormalities, gonadal defect, internal and external genital abnormalities. Investigations should be directed by the physical examination findings and the results of the radiological, endocrine and genetic investigation including FISH analysis, microarray analysis, DNA analysis using a variety of DSD panels and, when required, whole exome/genome sequencing.

Personal genome testing (PGT) that assesses risk for common diseases may influence the use of preventive health services, but outcome data are limited. We aimed to assess health service utilization following PGT. We conducted a retrospective matched cohort study at an adult health clinic. Medical records of clients who pursued PGT at their comprehensive health assessment (CHA) over a 1-year period (N = 388) were reviewed and compared to age- and sex-matched clients who underwent CHA but not PGT (N = 388). We measured condition-specific health services used post CHA up to two subsequent visits while accounting for confounding factors (e.g., family history, health status, and age). A relatively equal number of post CHA services were used by clients who pursued PGT and those who did not pursue PGT (52% and 48%, respectively). Overall and across the majority of conditions examined, clients' service utilization was significantly associated with health status, e.g., clients identified as "at risk" on CHA for heart attack used 2.86 times more services than clients not at risk. Pursuing PGT was not significantly associated with increased use of services post CHA overall or for most of the conditions examined. Our data demonstrate that health status rather than pursuing PGT is the strongest driver of service utilization in this population. Overall, pursuit of PGT and PGT results does not appear to significantly drive the utilization of downstream health services.

Disorders of brain formation can occur from pathogenic variants in various alpha and beta tubulin genes. Heterozygous pathogenic variants in the beta tubulin isotype A gene, TUBB2A, have been recently implicated in brain malformations, seizures, and developmental delay. Limited information is known regarding the phenotypic spectrum associated with pathogenic variants in this gene given the rarity of the condition. We report the sixth individual with a de novo heterozygous TUBB2A pathogenic variant, who presented with a severe neurological phenotype along with unique features of arthrogryposis multiplex congenita, optic nerve hypoplasia, dysmorphic facial features, and vocal cord paralysis, thereby expanding the gene-related phenotype.

Background and Objectives: Plastin 3 (PLS3) mutations are associated with an X-linked osteoporosis. Here we describe two new families with novel mutations, including one with a whole gene PLS3 deletion, and review the literature on 9 previously reported cases. Results: Hemizygous male carriers presented with multiple peripheral bone fractures, low bone mineral density (BMD), and vertebral compression fractures. Heterozygous female carriers did not have a history of fragility fractures, although 1 individual presented with low BMD. Apart from greyish-tinged sclera, no other extraskeletal features of osteogenesis imperfecta were identified. Histomorphometry from a transiliac bone biopsy in one of our index patients demonstrated significantly low trabecular bone volume with increased bone turnover. Bisphosphonate treatment was associated with a reduction in the fracture rate and increased bone density. Conclusion: Hemizygous mutations in PLS3 may cause a monogenic form of X-linked osteoporosis presenting in childhood with a nonspecific phenotype. No characteristic ocular, dental, or joint abnormalities are defined. When genetic testing is undertaken to investigate for primary causes of bone fragility, we suggest PLS3 be included in order not to miss this diagnosis.

Coats plus (CP) can be caused by mutations in the CTC1 component of CST, which promotes polymerase α (polα)/primase-dependent fill-in throughout the genome and at telomeres. The cellular pathology relating to CP has not been established. We identified a homozygous POT1 S322L substitution (POT1CP) in two siblings with CP. POT1CP induced a proliferative arrest that could be bypassed by telomerase. POT1CP was expressed at normal levels, bound TPP1 and telomeres, and blocked ATR signaling. POT1CP was defective in regulating telomerase, leading to telomere elongation rather than the telomere shortening observed in other telomeropathies. POT1CP was also defective in the maintenance of the telomeric C strand, causing extended 3′ overhangs and stochastic telomere truncations that could be healed by telomerase. Consistent with shortening of the telomeric C strand, metaphase chromosomes showed loss of telomeres synthesized by leading strand DNA synthesis. We propose that CP is caused by a defect in POT1/CST-dependent telomere fill-in. We further propose that deficiency in the fill-in step generates truncated telomeres that halt proliferation in cells lacking telomerase, whereas, in tissues expressing telomerase (e.g., bone marrow), the truncations are healed. The proposed etiology can explain why CP presents with features distinct from those associated with telomerase defects (e.g., dyskeratosis congenita).

The standard of care for first-tier clinical investigation of the aetiology of congenital malformations and neurodevelopmental disorders is chromosome microarray analysis (CMA) for copy-number variations (CNVs), often followed by gene(s)-specific sequencing searching for smaller insertion–deletions (indels) and single-nucleotide variant (SNV) mutations. Whole-genome sequencing (WGS) has the potential to capture all classes of genetic variation in one experiment; however, the diagnostic yield for mutation detection of WGS compared to CMA, and other tests, needs to be established. In a prospective study we utilised WGS and comprehensive medical annotation to assess 100 patients referred to a paediatric genetics service and compared the diagnostic yield versus standard genetic testing. WGS identified genetic variants meeting clinical diagnostic criteria in 34% of cases, representing a fourfold increase in diagnostic rate over CMA (8% ; P value=1.42E−05) alone and more than twofold increase in CMA plus targeted gene sequencing (13%; P value=0.0009). WGS identified all rare clinically significant CNVs that were detected by CMA. In 26 patients, WGS revealed indel and missense mutations presenting in a dominant (63%) or a recessive (37%) manner. We found four subjects with mutations in at least two genes associated with distinct genetic disorders, including two cases harbouring a pathogenic CNV and SNV. When considering medically actionable secondary findings in addition to primary WGS findings, 38% of patients would benefit from genetic counselling. Clinical implementation of WGS as a primary test will provide a higher diagnostic yield than conventional genetic testing and potentially reduce the time required to reach a genetic diagnosis.

Adolescence is a complex period of development that involves creating a sense of identity, autonomy, relationships and values. This stage of adjustment can be complicated by having a genetic condition. Genetic counseling can play an important role in providing information and support to this patient population; however, resources and guidelines are currently limited. In order to appropriately establish genetic counseling approaches and resource development, we investigated the experiences and perspectives of adolescents with a genetic condition with respect to their genetic counseling interactions. Using a qualitative exploratory approach, eleven semi-structured interviews were conducted with adolescents diagnosed with a genetic condition who received genetic counseling between the ages of 12 and 18 years at The Hospital for Sick Children. Transcripts were analyzed thematically using qualitative content analysis, from which three major interrelated themes emerged: 1) understanding the genetic counselor's role; 2) increasing perceived personal control; and 3) adolescent-specific factors influencing adaptation to one's condition. Additionally, a list of suggested tools and strategies for genetic counseling practice were elucidated. Our findings can contribute to the development of an adolescent-focused framework to enhance emerging genetic counseling approaches for this patient population, and can also facilitate the transition process from pediatric to adult care within patient and family-centered contexts.