Molecular characterization of 13 patients with PIK3CA-related overgrowth spectrum using a targeted deep sequencing approach.

Activating variants in the PIK3CA gene cause a heterogeneous spectrum of disorders that involve congenital or early-onset segmental/focal overgrowth, now referred to as PIK3CA-related overgrowth spectrum (PROS). Historically, the clinical diagnoses of patients with PROS included a range of distinct syndromes, including CLOVES syndrome, dysplastic megalencephaly, hemimegalencephaly, focal cortical dysplasia, Klippel-Trenaunay syndrome, CLAPO syndrome, fibroadipose hyperplasia or overgrowth, hemihyperplasia multiple lipomatosis, and megalencephaly capillary malformation-polymicrogyria (MCAP) syndrome. MCAP is a sporadic overgrowth disorder that exhibits core features of progressive megalencephaly, vascular malformations, distal limb malformations, cortical brain malformations, and connective tissue dysplasia. In 2012, our research group contributed to the identification of predominantly mosaic, gain-of-function variants in PIK3CA as an underlying genetic cause of the syndrome. Mosaic variants are technically more difficult to detect and require implementation of more sensitive sequencing technologies and less stringent variant calling algorithms. In this study, we demonstrated the utility of deep sequencing using the Illumina TruSight Oncology 500 (TSO500) sequencing panel in identifying variants with low allele fractions in a series of patients with PROS and suspected mosaicism: pathogenic, mosaic PIK3CA variants were identified in all 13 individuals, including 6 positive controls. This study highlights the importance of screening for low-level mosaic variants in PROS patients. The use of targeted panels with deep sequencing in clinical genetic testing laboratories would improve diagnostic yield and accuracy within this patient population.

Eye movement defects in KO zebrafish reveals SRPK3 as a causative gene for an X-linked intellectual disability.

Intellectual disability (ID) is a common neurodevelopmental disorder characterized by significantly impaired intellectual and adaptive functioning. X-linked ID (XLID) disorders, caused by defects in genes on the X chromosome, affect 1.7 out of 1,000 males. Employing exome sequencing, we identified three missense mutations (c.475C>G; p.H159D, c.1373C>A; p.T458N, and c.1585G>A; p.E529K) in the SRPK3 gene in seven XLID patients from three independent families. Clinical features common to the patients are intellectual disability, agenesis of the corpus callosum, abnormal smooth pursuit eye movement, and ataxia. SRPK proteins are known to be involved in mRNA processing and, recently, synaptic vesicle and neurotransmitter release. In order to validate SRPK3 as a novel XLID gene, we established a knockout (KO) model of the SRPK3 orthologue in zebrafish. In day 5 of larval stage, KO zebrafish showed significant defects in spontaneous eye movement and swim bladder inflation. In adult KO zebrafish, we found agenesis of cerebellar structures and impairments in social interaction. These results suggest an important role of SRPK3 in eye movements, which might reflect learning problems, intellectual disability, and other psychiatric disorders.

Dietary Intake Patterns and Lifestyle Behaviors of Pregnant Women Living in a Manitoba First Nations Community: Implications for Fetal Alcohol Spectrum Disorder.

The information on the nutrition status of women at-risk of carrying a child with fetal alcohol spectrum disorder (FASD) is scarce, particularly in the First Nations population living on reserve. This study examined and compared nutrition status, dietary intake, and lifestyle patterns of pregnant at-risk, defined as those who consume alcoholic drink during the current pregnancy, and non-at-risk women living in northern Manitoban community. Thirty-seven pregnant, First Nations women (at-risk n = 15; non-at-risk, n = 22) were recruited to participate in the study. A questionnaire, presented in paper and iPad formats, collected information on participants' demographics, dietary intake, lifestyle, pregnancy outcomes, and maternal health. A food frequency questionnaire and 24-h recall were used to determine nutrient intake. Nutrient values were assessed using Dietary Reference Intakes (DRI). At-risk and non-at-risk women were below the Canada Food Guide serving size recommended for Vegetable and Fruit, Grain, and Milk Products with 93%, 92%, and 93% of participants not meeting the recommendations, respectively. Women met the recommendations for vitamins A, B1, B12, C, niacin, choline, as well as calcium, and zinc. Sixty eight percentage (%) of participants did not meet the recommendations for folate and iron, and 97% for docosahexaenoic acid (DHA). Significant differences were observed between non-at-risk and at-risk women for mean % DRI intakes of vitamin C (313 ± 224 vs. 172 ± 81 mg/day), niacin (281 ± 123 vs. 198 ± 80 mg/day), folate (70 ± 38 vs. 10 ± 22 mcg/day), and iron (101 ± 74 vs. 74 ± 30 mg/day). The findings of this study lay a fundamental premise for the development of community nutrition programs, nutrition education, and nutrition intervention, such as community specific prenatal supplementation. These will assist in ensuring adequate maternal nutrient intake and benefit families and communities in Northern Manitoba with and without alcohol insult.

Orthopaedic Aspects of SAMS Syndrome.

The combination of short stature, auditory canal atresia, mandibular hypoplasia, and skeletal abnormalities (SAMS, OMIM: 602471) has been reported as an ultra-rare, autosomal-recessive developmental disorder with unique skeletal anomalies. To the present date, only four affected individuals have been reported. There are several striking orthopaedic diagnoses within the SAMS syndrome. In particular, the scapulohumoral synostosis and the bilateral congenital ventral dislocation of the hips. The purpose of this report is to underline the importance of recognizing pathognomic features of SAMS syndrome. Whenever a bilateral congenital ventral dislocation of the hips and/or a scapulohumoral synostosis is found or clinically suspected, SAMS syndrome should be considered as the primary diagnosis until proven otherwise.

Alternative genomic diagnoses for individuals with a clinical diagnosis of Dubowitz syndrome.

Dubowitz syndrome (DubS) is considered a recognizable syndrome characterized by a distinctive facial appearance and deficits in growth and development. There have been over 200 individuals reported with Dubowitz or a "Dubowitz-like" condition, although no single gene has been implicated as responsible for its cause. We have performed exome (ES) or genome sequencing (GS) for 31 individuals clinically diagnosed with DubS. After genome-wide sequencing, rare variant filtering and computational and Mendelian genomic analyses, a presumptive molecular diagnosis was made in 13/27 (48%) families. The molecular diagnoses included biallelic variants in SKIV2L, SLC35C1, BRCA1, NSUN2; de novo variants in ARID1B, ARID1A, CREBBP, POGZ, TAF1, HDAC8, and copy-number variation at1p36.11(ARID1A), 8q22.2(VPS13B), Xp22, and Xq13(HDAC8). Variants of unknown significance in known disease genes, and also in genes of uncertain significance, were observed in 7/27 (26%) additional families. Only one gene, HDAC8, could explain the phenotype in more than one family (N = 2). All but two of the genomic diagnoses were for genes discovered, or for conditions recognized, since the introduction of next-generation sequencing. Overall, the DubS-like clinical phenotype is associated with extensive locus heterogeneity and the molecular diagnoses made are for emerging clinical conditions sharing characteristic features that overlap the DubS phenotype.

Profile of Mothers of Children with Fetal Alcohol Spectrum Disorder: A Population-Based Study in Canada.

OBJECTIVE: To compare the characteristics of mothers of children with Fetal Alcohol Spectrum Disorder (FASD) with mothers of typically developing control children. METHODS: The study utilized a cross-sectional, observational design, using active case ascertainment. Biological mothers were interviewed using a standardized retrospective questionnaire to collect data on demographics, living environment, pregnancy history, nutrition, alcohol and other drug use prior to and following pregnancy recognition. RESULTS: A total of 173 mothers were interviewed. Of these, 19 had a child who was diagnosed with FASD, five had a child who had received a deferred FASD diagnosis, and 37 had children who were selected into the control group as typically developing children. The remaining 112 mothers had children who did not meet diagnostic criteria for FASD. The mothers of children with FASD did not differ significantly from mothers of the control group children with respect to age, ethnicity, marital status, and employment status at the time of pregnancy. However, mothers of children with FASD had lower levels of education (p < 0.01) and were more likely to have received financial support (p < 0.05) at the time of pregnancy, to have smoked tobacco (p < 0.001), and to have used marijuana or hashish (p < 0.01) prior to pregnancy recognition, compared with mothers of control children. All mothers of children with FASD reported alcohol consumption prior to pregnancy recognition; however, only 10.5% reported alcohol consumption following pregnancy recognition. None of the mothers interviewed reported any drug use following pregnancy recognition. CONCLUSIONS: Population-based preventive interventions, including repeated screening, monitoring, and education regarding the effects of alcohol use, as well as other substances, before and during pregnancy, are needed to eliminate risk for FASD and other negative consequences on child and maternal health.

Population-based prevalence of fetal alcohol spectrum disorder in Canada.

BACKGROUND: Fetal alcohol spectrum disorder (FASD) is one of the most disabling potential outcomes of prenatal alcohol exposure. The population-based prevalence of FASD among the general population of Canada was unknown. The objective of this study was to determine the population-based prevalence of FASD among elementary school students, aged 7 to 9 years, in the Greater Toronto Area (GTA) in Ontario, Canada. METHODS: This screening study used a cross-sectional, observational design utilizing active case ascertainment, along with retrospective collection of prenatal alcohol exposure information. Data collection involved two phases. Phase I consisted of taking growth measurements, a dysmorphology examination, and obtaining a history of behavioral and/or learning problems. Phase II consisted of a neurodevelopmental assessment, maternal interview, and behavioral observations/ratings by parents/guardians. Final diagnostic screening conclusions were made by consensus by a team of experienced multidisciplinary experts during case conferences, using the 2005 Canadian guidelines for FASD diagnosis. The prevalence of FASD was estimated, taking into consideration the selection rate, which was used to account for students who dropped out or were lost to follow-up during each phase. Monte Carlo simulations were employed to derive the confidence interval (CI) for the point estimates. RESULTS: A total of 2555 students participated. A total of 21 cases of suspected FASD were identified. The prevalence of FASD was estimated to be 18.1 per 1000, or about 1.8%. Using a less conservative approach (sensitivity analysis), the prevalence of FASD was estimated to be 29.3 per 1000, or about 2.9%. Therefore, the population-based prevalence of FASD is likely to range between 2 and 3% among elementary school students in the GTA in Ontario, Canada. CONCLUSIONS: This study provides the first population-based estimate of the prevalence of FASD in Canada. The estimate is approximately double or possibly even triple previous crude estimates. FASD prevalence exceeds that of other common birth defects such as Down's syndrome, spina bifida, trisomy 18, as well as autism spectrum disorder in Canada. More effective prevention strategies targeting alcohol use during pregnancy, surveillance of FASD, and timely interventions and support to individuals with FASD and their families are urgently needed.

Kabuki syndrome: international consensus diagnostic criteria.

BACKGROUND: Kabuki syndrome (KS) is a clinically recognisable syndrome in which 70% of patients have a pathogenic variant in KMT2D or KDM6A. Understanding the function of these genes opens the door to targeted therapies. The purpose of this report is to propose diagnostic criteria for KS, particularly when molecular genetic testing is equivocal. METHODS: An international group of experts created consensus diagnostic criteria for KS. Systematic PubMed searches returned 70 peer-reviewed publications in which at least one individual with molecularly confirmed KS was reported. The clinical features of individuals with known mutations were reviewed. RESULTS: The authors propose that a definitive diagnosis can be made in an individual of any age with a history of infantile hypotonia, developmental delay and/or intellectual disability, and one or both of the following major criteria: (1) a pathogenic or likely pathogenic variant in KMT2D or KDM6A; and (2) typical dysmorphic features (defined below) at some point of life. Typical dysmorphic features include long palpebral fissures with eversion of the lateral third of the lower eyelid and two or more of the following: (1) arched and broad eyebrows with the lateral third displaying notching or sparseness; (2) short columella with depressed nasal tip; (3) large, prominent or cupped ears; and (4) persistent fingertip pads. Further criteria for a probable and possible diagnosis, including a table of suggestive clinical features, are presented. CONCLUSION: As targeted therapies for KS are being developed, it is important to be able to make the correct diagnosis, either with or without molecular genetic confirmation.

UBE2A-related X-linked intellectual disability.

UBE2A-related X-linked intellectual disability is characterized by a distinctive facial phenotype (dense eyebrows and eyelashes, synophrys, hypertelorism, upslanted palpebral fissures, wide mouth, and thin lips), generalized hirsutism, hypoplastic genitalia, short stature, hypotonia, seizures, and severe intellectual disability. Five affected males in two families are described here and compared with the previously reported 17 males in eight families. The new cases are notable for the absence of nail dystrophy, previously considered a defining manifestation, and for the presence of hypogammaglobulinemia and adult-onset ataxia.

Copy number variation in fetal alcohol spectrum disorder.

Fetal alcohol spectrum disorder (FASD) is characterized by a combination of neurological, developmental, and congenital defects that may occur as a consequence of prenatal alcohol exposure. Earlier reports showed that large chromosomal anomalies may link to FASD. Here, we examined the prevalence and types of copy number variations (CNVs) in FASD cases previously diagnosed by a multidisciplinary FASD team in sites across Canada. We genotyped 95 children with FASD and 87 age-matched, typically developing controls on the Illumina Human Omni2.5 SNP (single nucleotide polymorphisms) array platform. We compared their CNVs with those of 10 851 population controls to identify rare CNVs (<0.1% frequency), which may include large unbalanced chromosomal abnormalities, that might be relevant to FASD. In 12/95 (13%) of the FASD cases, rare CNVs were found that impact potentially clinically relevant developmental genes, including the CACNA1H involved in epilepsy and autism, the 3q29 deletion disorder, and others. Our results show that a subset of children diagnosed with FASD have chromosomal deletions and duplications that may co-occur or explain the neurodevelopmental impairments in a diagnosed cohort of FASD individuals. Children suspected to have FASD with or without sentinel facial features of fetal alcohol syndrome and neurodevelopmental delays should potentially be evaluated by a clinical geneticist and possibly have genetic investigations as appropriate to exclude other etiologies.

DNA methylation as a predictor of fetal alcohol spectrum disorder.

Background: Fetal alcohol spectrum disorder (FASD) is a developmental disorder that manifests through a range of cognitive, adaptive, physiological, and neurobiological deficits resulting from prenatal alcohol exposure. Although the North American prevalence is currently estimated at 2-5%, FASD has proven difficult to identify in the absence of the overt physical features characteristic of fetal alcohol syndrome. As interventions may have the greatest impact at an early age, accurate biomarkers are needed to identify children at risk for FASD. Building on our previous work identifying distinct DNA methylation patterns in children and adolescents with FASD, we have attempted to validate these associations in a different clinical cohort and to use our DNA methylation signature to develop a possible epigenetic predictor of FASD. Methods: Genome-wide DNA methylation patterns were analyzed using the Illumina HumanMethylation450 array in the buccal epithelial cells of a cohort of 48 individuals aged 3.5-18 (24 FASD cases, 24 controls). The DNA methylation predictor of FASD was built using a stochastic gradient boosting model on our previously published dataset FASD cases and controls (GSE80261). The predictor was tested on the current dataset and an independent dataset of 48 autism spectrum disorder cases and 48 controls (GSE50759). Results: We validated findings from our previous study that identified a DNA methylation signature of FASD, replicating the altered DNA methylation levels of 161/648 CpGs in this independent cohort, which may represent a robust signature of FASD in the epigenome. We also generated a predictive model of FASD using machine learning in a subset of our previously published cohort of 179 samples (83 FASD cases, 96 controls), which was tested in this novel cohort of 48 samples and resulted in a moderately accurate predictor of FASD status. Upon testing the algorithm in an independent cohort of individuals with autism spectrum disorder, we did not detect any bias towards autism, sex, age, or ethnicity. Conclusion: These findings further support the association of FASD with distinct DNA methylation patterns, while providing a possible entry point towards the development of epigenetic biomarkers of FASD.

Diagnosis of fetal alcohol spectrum disorder: current practices and future considerations.

This paper discusses the current state of knowledge and practice for diagnosing fetal alcohol spectrum disorder (FASD). The strengths and challenges of different models of diagnosis are compared. Some models require a team approach for evaluation, while other approaches assume that a clinician in his or her office provides a diagnosis based on a review of the patient's medical and social history, behaviour, and physical examination. The author reviews the emergence of new information from recent advances in genetics, imaging, and electrophysiology that has the potential to lead to changes in practice and improved reliability of an FASD diagnosis.

Human Brain Abnormalities Associated With Prenatal Alcohol Exposure and Fetal Alcohol Spectrum Disorder.

Fetal alcohol spectrum disorder (FASD) is a common neurodevelopmental problem, but neuropathologic descriptions are rare and focused on the extreme abnormalities. We conducted a retrospective survey (1980-2016) of autopsies on 174 individuals with prenatal alcohol exposure or an FASD diagnosis. Epidemiologic details and neuropathologic findings were categorized into 5 age groups. Alcohol exposure was difficult to quantify. When documented, almost all mothers smoked tobacco, many abused other substances, and prenatal care was poor or nonexistent. Placental abnormalities were common (68%) in fetal cases. We identified micrencephaly (brain weight <5th percentile) in 31, neural tube defects in 5, isolated hydrocephalus in 6, corpus callosum defects in 6 (including some with complex anomalies), probable prenatal ischemic lesions in 5 (excluding complications of prematurity), minor subarachnoid heterotopias in 4, holoprosencephaly in 1, lissencephaly in 1, and cardiac anomalies in 26 cases. The brain abnormalities associated with prenatal alcohol exposure are varied; cause-effect relationships cannot be determined. FASD is likely not a monotoxic disorder. The animal experimental literature, which emphasizes controlled exposure to ethanol alone, is therefore inadequate. Prevention must be the main societal goal, however, a clear understanding of the neuropathology is necessary for provision of care to individuals already affected.

Overview of the Genetic Basis and Epigenetic Mechanisms that Contribute to FASD Pathobiology.

Prenatal alcohol (ethanol) exposure (PAE) is the underlying cause for a variety of birth defects and neurodevelopmental deficits referred to as "Fetal Alcohol Spectrum Disorders (FASD)". The more visible phenotypes caused by PAE include growth retardation, and characteristic craniofacial abnormalities associated with functional and structural damage to the central nervous system. Ethanol is a teratogenic agent itself; but it can also alter gene expression. These changes may contribute to the spectrum of effects and different phenotypes that are dependent on alcohol metabolism, as well as the timing and duration of alcohol exposure. Evidence from both human patients and animal models show that genetic factors and epigenetic mechanisms such as DNA methylation, histone post-translational modifications and noncoding RNAs, contribute to the gene expression changes caused by ethanol. Not all embryos that are exposed to alcohol during development exhibit FASD symptoms after birth. FASD patients may present severe birth defects, while others are normal in physical appearance but present a variety of cognitive and behavioral difficulties. It has been hypothesized that maternal and paternal genetic factors may contribute to the sensitivity, resistance or vulnerability of the fetus to alcohol. Moreover, the epigenome is highly sensitive to a multitude of environmental insults including PAE. Studies also show 'transgenerational' effects of alcohol. In such cases, maternal or paternal preconception alcohol consumption could lead to FASD-like phenotypes in the newborn. Thus, the phenotypes in FASD can be modified by interplay between maternal/paternal genetic factors and epigenetic mechanisms. This current review summarizes the contribution of genetic and epigenetic mechanisms in FASD pathobiology, and how this information could be utilized for prevention, early diagnosis and potentially treatment of the affected individuals.

DNA methylation signature of human fetal alcohol spectrum disorder.

BACKGROUND: Prenatal alcohol exposure is the leading preventable cause of behavioral and cognitive deficits, which may affect between 2 and 5 % of children in North America. While the underlying mechanisms of alcohol's effects on development remain relatively unknown, emerging evidence implicates epigenetic mechanisms in mediating the range of symptoms observed in children with fetal alcohol spectrum disorder (FASD). Thus, we investigated the effects of prenatal alcohol exposure on genome-wide DNA methylation in the NeuroDevNet FASD cohort, the largest cohort of human FASD samples to date. METHODS: Genome-wide DNA methylation patterns of buccal epithelial cells (BECs) were analyzed using the Illumina HumanMethylation450 array in a Canadian cohort of 206 children (110 FASD and 96 controls). Genotyping was performed in parallel using the Infinium HumanOmni2.5-Quad v1.0 BeadChip. RESULTS: After correcting for the effects of genetic background, we found 658 significantly differentially methylated sites between FASD cases and controls, with 41 displaying differences in percent methylation change >5 %. Furthermore, 101 differentially methylated regions containing two or more CpGs were also identified, overlapping with 95 different genes. The majority of differentially methylated genes were highly expressed at the level of mRNA in brain samples from the Allen Brain Atlas, and independent DNA methylation data from cortical brain samples showed high correlations with BEC DNA methylation patterns. Finally, overrepresentation analysis of genes with up-methylated CpGs revealed a significant enrichment for neurodevelopmental processes and diseases, such as anxiety, epilepsy, and autism spectrum disorders. CONCLUSIONS: These findings suggested that prenatal alcohol exposure is associated with distinct DNA methylation patterns in children and adolescents, raising the possibility of an epigenetic biomarker of FASD.

Relationships between Head Circumference, Brain Volume and Cognition in Children with Prenatal Alcohol Exposure.

Head circumference is used together with other measures as a proxy for central nervous system damage in the diagnosis of fetal alcohol spectrum disorders, yet the relationship between head circumference and brain volume has not been investigated in this population. The objective of this study is to characterize the relationship between head circumference, brain volume and cognitive performance in a large sample of children with prenatal alcohol exposure (n = 144) and healthy controls (n = 145), aged 5-19 years. All participants underwent magnetic resonance imaging to yield brain volumes and head circumference, normalized to control for age and sex. Mean head circumference, brain volume, and cognitive scores were significantly reduced in the prenatal alcohol exposure group relative to controls, albeit with considerable overlap between groups. Males with prenatal alcohol exposure had reductions in all three measures, whereas females with prenatal alcohol exposure had reduced brain volumes and cognitive scores, but no difference in head circumference relative to controls. Microcephaly (defined here as head circumference ≤ 3rd percentile) occurred more often in prenatal alcohol exposed participants than controls, but 90% of the exposed sample had head circumferences above this clinical cutoff indicating that head circumference is not a sensitive marker of prenatal alcohol exposure. Normalized head circumference and brain volume were positively correlated in both groups, and subjects with very low head circumference typically had below-average brain volumes. Conversely, over half of the subjects with very low brain volumes had normal head circumferences, which may stem from differential effects of alcohol on the skeletal and nervous systems. There were no significant correlations between head circumference and any cognitive score. These findings confirm group-level reductions in head circumference and increased rates of microcephaly in children with prenatal alcohol exposure, but raise concerns about the predictive value of this metric at an individual-subject level.