Prenatal findings in 11 cases with craniofacial microsomia using the Alberta Congenital Anomalies Surveillance System, 1997-2019.

Craniofacial microsomia (CFM) primarily includes specific head and neck anomalies that co-occur more frequently than expected. The anomalies are usually asymmetric and affect craniofacial features; however, there are frequently additional anomalies of variable severity. Published prenatal findings for CFM are limited. This study contributes 11 cases with CFM and their anomalies identified prenatally. Cases born between January 1, 1997 and December 31, 2019 with CFM were abstracted from the Alberta Congenital Anomalies Surveillance System, which is a population-based program ascertaining congenital anomalies for livebirths, stillbirths, and termination of pregnancies for fetal anomalies. There were 11 cases ascertained with prenatal findings including facial anomalies: one each with left cleft lip, right microtia, and bilateral microphthalmia. Two cases had vertebral anomalies. In addition, anomalies of the kidneys, brain, heart, and radial ray were identified. Six (55%) had a single umbilical artery, five (45%) were small for gestational age, and three (27%) were from a twin pregnancy that were discordant for anomalies. Four (36%) overlapped another proposed recurrent constellations of embryonic malformation condition. This study describes prenatal findings for 11 cases with CFM. Comparable to prior published cases, there were recurring anomalies on prenatal imaging, including anomalies of the brain, eye, heart, kidneys, and radial ray, which may aid in the prenatal diagnosis of CFM.

Axenfeld-Rieger syndrome: more than meets the eye.

BACKGROUND: Axenfeld-Rieger syndrome (ARS) is characterised by typical anterior segment anomalies, with or without systemic features. The discovery of causative genes identified ARS subtypes with distinct phenotypes, but our understanding is incomplete, complicated by the rarity of the condition. METHODS: Genetic and phenotypic characterisation of the largest reported ARS cohort through comprehensive genetic and clinical data analyses. RESULTS: 128 individuals with causative variants in PITX2 or FOXC1, including 81 new cases, were investigated. Ocular anomalies showed significant overlap but with broader variability and earlier onset of glaucoma for FOXC1-related ARS. Systemic anomalies were seen in all individuals with PITX2-related ARS and the majority of those with FOXC1-related ARS. PITX2-related ARS demonstrated typical umbilical anomalies and dental microdontia/hypodontia/oligodontia, along with a novel high rate of Meckel diverticulum. FOXC1-related ARS exhibited characteristic hearing loss and congenital heart defects as well as previously unrecognised phenotypes of dental enamel hypoplasia and/or crowding, a range of skeletal and joint anomalies, hypotonia/early delay and feeding disorders with structural oesophageal anomalies in some. Brain imaging revealed highly penetrant white matter hyperintensities, colpocephaly/ventriculomegaly and frequent arachnoid cysts. The expanded phenotype of FOXC1-related ARS identified here was found to fully overlap features of De Hauwere syndrome. The results were used to generate gene-specific management plans for the two types of ARS. CONCLUSION: Since clinical features of ARS vary significantly based on the affected gene, it is critical that families are provided with a gene-specific diagnosis, PITX2-related ARS or FOXC1-related ARS. De Hauwere syndrome is proposed to be a FOXC1opathy.

Craniofacial Microsomia, Associated Congenital Anomalies, and Risk Factors in 63 Cases from the Alberta Congenital Anomalies Surveillance System.

OBJECTIVE: To report associated congenital anomalies with unexplained craniofacial microsomia (CFM) and the phenotypic overlap with other recurrent constellations of embryonic malformations (RCEM), and to assess prenatal and perinatal risk factors. STUDY DESIGN: This is a retrospective cross-sectional study. Cases with CFM, delivered between January 1, 1997, and December 31, 2019, were abstracted from the population-based Alberta Congenital Anomalies Surveillance System. Livebirths, stillbirths, and early fetal losses were reviewed to include all types of pregnancy outcomes along the spectrum of this condition. Prenatal and perinatal risk factors were compared with the Alberta birth population to assess differences between the 2 groups. RESULTS: There were 63 cases with CFM, yielding a frequency of 1 per 16 949. There was a high rate of cases (65%) with anomalies outside the craniofacial and vertebral regions. Congenital heart defects were the most common (33.3%). A single umbilical artery was found in 12.7% of cases. The twin/triplet rate of 12.7% was significantly higher than the Alberta rate of 3.3% (P < .0001). There was an overlap with a second RCEM condition in 9.5% of cases. CONCLUSIONS: Although CFM is primarily a craniofacial condition, the majority of cases have congenital anomalies affecting other systems requiring additional assessments, including an echocardiogram, renal ultrasound examination, and a complete vertebral radiograph. The high rate of an associated single umbilical artery raises the possibility of a related etiological mechanism. Our findings support the proposed concept of RCEM conditions.

Phenotype and pathology of the dilated cardiomyopathy with ataxia syndrome in children.

The dilated cardiomyopathy with ataxia syndrome (DCMA) is an autosomal recessive mitochondrial disease caused by mutations in the DnaJ heat shock protein family (Hsp40) member C19 (DNAJC19) gene. DCMA or 3-methylglutaconic aciduria type V is globally rare, but the largest number of patients in the world is found in the Hutterite population of southern Alberta in Canada. We provide an update on phenotypic findings, natural history, pathological findings, and our clinical experience. We analyzed all available records for 43 patients diagnosed with DCMA between 2005 and 2015 at the Alberta Children's Hospital. All patients studied were Hutterite and homozygous for the causative DNAJC19 variant (c.130-1G>C, IVS3-1G>C) and had elevated levels of 3-methyglutaconic acid. We calculated a birth prevalence of 1.54 cases per 1000 total births in the Hutterite community. Children were small for gestational age at birth and frequently required supplemental nutrition (63%) or surgical placement of a gastrostomy tube (35%). Early mortality in this cohort was high (40%) at a median age of 13 months (range 4-294 months). Congenital anomalies were common as was dilated cardiomyopathy (50%), QT interval prolongation (83%), and developmental delay (95%). Tissue pathology was analyzed in a limited number of patients and demonstrated subendocardial fibrosis in the heart, macrovesicular steatosis and fibrosis in the liver, and structural abnormalities in mitochondria. This report provides clinical details for a cohort of children with DCMA and the first presentation of tissue pathology for this disorder. Despite sharing common genetic etiology and environment, the disease is highly heterogeneous for reasons that are not understood. DCMA is a clinically heterogeneous systemic mitochondrial disease with significant morbidity and mortality that is common in the Hutterite population of southern Alberta.

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.

Prevalence rates study of selected isolated non-Mendelian congenital anomalies in the Hutterite population of Alberta, 1980-2016.

A study of the prevalence rates for selected isolated non-Mendelian congenital anomalies in the Hutterite Brethren of Alberta, Canada was undertaken to further examine longitudinal data in this isolated community that was last reported in 1985 (Lowry et al., 1985), although there are numerous publications on recessive disorders (Boycott et al., 2008; Triggs-Raine et al., 2016). Cases were ascertained from the Alberta Congenital Anomaly Surveillance System for the years 1997-2016. Since our initial results showed some surprising findings in the Hutterite Brethren, such as zero cases of spina bifida, cleft lip and palate, gastroschisis, and omphalocele, and a significant excess of cases with hypospadias, we extended the study to prior years (1980-1996) for selected anomalies. For the extended study period (1980-2016), there was a significant increased prevalence of hypospadias, tetralogy of Fallot and tricuspid atresia in the Hutterite population, and although not statistically significant, zero cases of cleft lip with cleft palate, gastroschisis and omphalocele were confirmed. Further research is needed to determine the precise effects of rural environmental exposures, lifestyle factors, and genetic associations for selected multifactorial congenital anomalies.

Disease coding systems for arthrogryposis multiplex congenita.

Arthrogryposis multiplex congenita (AMC) encompasses many different conditions, involves many different genes and thus can be very complex. Using historical disease coding systems to document syndrome diagnoses and anomalies associated with AMC is often challenging. However, disease coding systems are necessary to provide opportunities for a standard language to be maintained and pertinent data to be identified in the pediatric AMC registry, congenital anomalies surveillance systems, and routine or administrative health information systems. The ICD-10, Orphanet, Online Mendelian Inheritance in Man, and the Human Phenotype Ontology coding and classification systems are described to establish a comprehensive coding strategy. This strategy will provide a necessary tool to contribute to a better understanding of AMC and ultimately improve the health of individuals with AMC.

Congenital limb deficiencies and major associated anomalies in Alberta for the years 1980-2012.

There is a wide range of the proportion of congenital anomalies associated with limb deficiencies reported in the literature. This variation is primarily attributed to methodology and classification differences. The distribution of associated anomalies among cases with congenital limb deficiencies in Alberta born between January 1, 1980 and December 31, 2012 is described. Of the 170 cases identified, most were live born (75.3%), male (61.8%), had longitudinal limb deficiencies (78.8%), and had associated anomalies outside the musculoskeletal system (77.6%). Significant associations between the preaxial longitudinal group and the central nervous, gastrointestinal, and cardiovascular systems are reported as well as between the postaxial longitudinal group and congenital hip and foot anomalies. Probable and possible syndrome diagnoses are described for cases with recognized malformation patterns.

Views on the Oberg-Manske-Tonkin Classification System for Congenital Anomalies of the Hand and Upper Limb.

A new classification system was proposed by Tonkin et al as a replacement for the Swanson/International Federation of Societies for Surgery of the Hand system. We have reviewed their aims and have pointed out a number of problems that will make it difficult to be universally accepted.

Mutations in BICD2, which encodes a golgin and important motor adaptor, cause congenital autosomal-dominant spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a heterogeneous group of neuromuscular disorders caused by degeneration of lower motor neurons. Although functional loss of SMN1 is associated with autosomal-recessive childhood SMA, the genetic cause for most families affected by dominantly inherited SMA is unknown. Here, we identified pathogenic variants in bicaudal D homolog 2 (Drosophila) (BICD2) in three families afflicted with autosomal-dominant SMA. Affected individuals displayed congenital slowly progressive muscle weakness mainly of the lower limbs and congenital contractures. In a large Dutch family, linkage analysis identified a 9q22.3 locus in which exome sequencing uncovered c.320C>T (p.Ser107Leu) in BICD2. Sequencing of 23 additional families affected by dominant SMA led to the identification of pathogenic variants in one family from Canada (c.2108C>T [p.Thr703Met]) and one from the Netherlands (c.563A>C [p.Asn188Thr]). BICD2 is a golgin and motor-adaptor protein involved in Golgi dynamics and vesicular and mRNA transport. Transient transfection of HeLa cells with all three mutant BICD2 cDNAs caused massive Golgi fragmentation. This observation was even more prominent in primary fibroblasts from an individual harboring c.2108C>T (p.Thr703Met) (affecting the C-terminal coiled-coil domain) and slightly less evident in individuals with c.563A>C (p.Asn188Thr) (affecting the N-terminal coiled-coil domain). Furthermore, BICD2 levels were reduced in affected individuals and trapped within the fragmented Golgi. Previous studies have shown that Drosophila mutant BicD causes reduced larvae locomotion by impaired clathrin-mediated synaptic endocytosis in neuromuscular junctions. These data emphasize the relevance of BICD2 in synaptic-vesicle recycling and support the conclusion that BICD2 mutations cause congenital slowly progressive dominant SMA.

A 2q24.3q31.1 microdeletion found in a patient with Filippi-like syndrome phenotype: a case report.

Filippi syndrome is characterized by developmental delay, growth failure, cryptorchidism, bilateral hand and foot syndactyly, and facial dysmorphism. The 2q24q31 contiguous deletion syndrome has similarly been associated with hand and foot anomalies, growth retardation, microcephaly, characteristic facies with a broad prominent nasal root and thin alae nasi, and intellectual disability. We present a patient with this deletion who has a Filippi-like phenotype, which may be the first causative cytogenetic result in this syndrome. This suggests the importance of array comparative genomic hybridization in evaluation of patients with Filippi syndrome, and suggests that the inheritance may not always be autosomal recessive.

De novo exon 1 missense mutations of SKI and Shprintzen-Goldberg syndrome: two new cases and a clinical review.

Shprintzen-Goldberg syndrome (OMIM #182212) is a connective tissue disorder characterized by craniosynostosis, distinctive craniofacial features, skeletal abnormalities, marfanoid body habitus, aortic dilatation, and intellectual disability. Mutations in exon 1 of SKI have recently been identified as being responsible for approximately 90% of reported individuals diagnosed clinically with Shprintzen-Goldberg syndrome. SKI is a known regulator of TGFß signaling. Therefore, like Marfan syndrome and Loeys-Dietz syndrome, Shprintzen-Goldberg syndrome is likely caused by deregulated TGFß signals, explaining the considerable phenotypic overlap between these three disorders. We describe two additional patients with exon 1 SKI mutations and review the clinical features and literature of Shprintzen-Goldberg syndrome.

Validation of congenital anomaly coding in Canada's administrative databases compared with a congenital anomaly registry.

BACKGROUND: Congenital anomaly (CA) surveillance provides epidemiologic data that are necessary for health planning. Approaches to CA surveillance vary; however, an increasing number of jurisdictions rely on administrative health databases for case ascertainment. This study aimed to assess the validity of CA coding in three administrative databases compared with a CA registry. METHODS: A cohort of 5862 live and stillborn infants from Calgary Alberta Canada was created through linking 12 clinical and administrative databases. Diagnostic codes for all health care contacts (hospitalizations, emergency room visits, out-patient physician visits) in the first 3 months of life were examined for relevant International Classification of Disease codes. Sensitivity, positive predictive values, and kappa coefficients were calculated, and data from the Alberta Congenital Anomalies Surveillance System was used as the reference standard. RESULTS: The ability of administrative data to accurately ascertain CAs varied by data source and the specificity of the diagnosis. Consistently, hospitalization data out-performed other administrative data sources in terms of sensitivity, positive predictive values, and kappa. Kappa scores for CAs easily visible at birth ranged from moderate (0.62 for emergency room visits and 0.65 for out-patient physician claims) to good (0.83 for hospitalization data) depending on the data source. CONCLUSION: The validity of CA coding in administrative databases compared with a CA registry varies by database used and by CA studied. This has important implications for national surveillance efforts. Condition-specific validity should be assessed locally before use of these data sources for research or planning purposes.

Stability of orofacial clefting rate in alberta, 1980-2011.

Objective : To determine the prevalence and trends of orofacial clefts in Alberta (Canada) over a 33-year period (1980 through 2011) and to determine whether the trends differ for subcategories of orofacial clefts for the period from 1997 through 2011. Design : A prevalence study based on the Alberta Congenital Anomalies Surveillance System, which has multiple sources of ascertainment, capability of verification, and an upper age limit of 1 year. Inclusion : All live born and stillborn babies and fetal deaths less than 20 weeks' gestation (including terminations of pregnancy) born in Alberta of mothers who reside in Alberta. Results and Conclusions : Rates for cleft lip with or without cleft palate and cleft palate only have been very stable over the 33-year period (1980 through 2011). These rates include all clefts (isolated, syndromes, recognizable conditions, chromosomal and multiple congenital anomalies). Ascertainment of fetal deaths less than 20 weeks' gestation began in 1997. There are trends for the 1997 through 2011 cohort with a marginally significant increase for cleft lip with or without cleft palate in the isolated category and a significant decrease for cleft palate, mainly in the associated groups. The impact of folic acid fortification and/or multivitamins/folic acid supplementation reports in the literature have shown no consensus with respect to a change in the prevalence of orofacial clefts. It is unclear whether folic acid fortification has had any impact in Alberta.

Publicly funded healthcare costs associated with orofacial clefts for children born in Alberta, Canada between 2002 and 2018.

BACKGROUND: Orofacial clefts (OFCs) include cleft palate (CP), cleft lip (CL), and cleft lip with cleft palate (CLP) and require multidisciplinary healthcare services. Alberta, Canada has a publicly funded, universal access healthcare system. This study determined publicly funded healthcare costs for children with an OFC and compared these costs to children without congenital anomalies. METHODS: This retrospective population-based cohort analysis used the Alberta Congenital Anomalies Surveillance System to identify children born between 2002 and 2018 with an isolated OFC. They were matched 1:1 to a reference cohort based on sex and year of birth. The study population included 1614 children, from birth to 17 years of age linked to administrative databases to estimate annual inpatient and outpatient costs. Average annual all-cause costs were compared using two-sample independent t tests. RESULTS: The mean total cleft-related costs per patient were highest for children with CLP ($74,138 CAD, standard deviation (SD) $43,447 CAD), followed by CP ($53,062 CAD, SD $74,366 CAD), and CL ($35,288 CAD, SD $49,720 CAD). The mean total all-cause costs per child were statistically significantly higher (p < .001) in children with an OFC ($56,305 CAD, SD $57,744 CAD) compared to children without a congenital anomaly ($18,600 CAD, SD $61,300 CAD). CONCLUSIONS: Despite public health strategies to mitigate risk factors, the trend for OFCs has remained stable in Alberta, Canada for over 20 years. The costs reported are useful to other jurisdictions for comparison, and to families, healthcare professionals, service planners, and policy makers.

Congenital heart defects and major structural noncardiac anomalies in Alberta, Canada, 1995-2002.

BACKGROUND: Although the majority of congenital heart defects (CHDs) occur in isolation, a significant number occur with noncardiac anomalies. This study determined the proportion of noncardiac anomalies among CHD cases in Alberta. METHODS: Records of infants and children born in Alberta between January 1, 1995, to December 31, 2002, were searched using multiple sources of ascertainment in addition to the Alberta Congenital Anomalies Surveillance System (ACASS) (Alberta Health and Wellness, 2012). Each case was assigned to one CHD category and was further categorized into one of the following groups: isolated CHD, syndromes, chromosomal, associations and sequences, teratogens, Mendelian, neoplasia, heterotaxy, multiple minor anomalies, and multiple major anomalies. RESULTS: Of all 3751 CHD cases (prevalence 12.42/1000 total births: confidence interval, 12.03-12.83), 75% were isolated, 10% had a chromosomal etiology, and 9% had multiple major anomalies. All other categories accounted for <2% each. The most commonly associated major noncardiac anomalies were musculoskeletal (MSK) (24%) followed by anomalies of the urinary tract (14%), gastrointestinal system (GI) (11%), and central nervous system (CNS) (11%). CONCLUSIONS: This is both a population-based and clinical study using a classification scheme that could help to determine possible etiologic factors contributing to CHD. By eliminating known etiologies such as chromosomal and single gene, future studies can focus on the remainder to evaluate possible preventive measures. The most commonly associated major noncardiac anomalies involve the MSK system, followed by the urinary, GI, and CNS systems.

Folic acid fortification and the birth prevalence of congenital heart defect cases in Alberta, Canada.

BACKGROUND: Congenital heart defects (CHDs) are the most common type of congenital anomaly. The precise etiology is unknown and the development of successful primary prevention strategies is challenging. Folic acid may have a protective role; however published results have been inconsistent. This study examines the impact of mandatory folic acid fortification (FAF) on the prevalence of CHDs. METHODS: CHD cases were ascertained using the Alberta Congenital Anomalies Surveillance System, Pediatric Cardiology Clinics, Pathology, and hospital records. The birth prevalence and odds ratios (OR) of isolated CHD cases (i.e., without noncardiac anomalies) were calculated comparing pre-FAF (1995-1997) with post-FAF (1999-2002). RESULTS: The prevalence of isolated CHD cases remained relatively unchanged when pre-FAF (9.34, 95% confidence interval [CI] 8.79-9.92) was compared with post-FAF (9.41, 95% CI, 8.93-9.91). Left ventricular outflow tract obstruction (LVOTO) decreased post-FAF (OR, 0.76; 95% CI, 0.61-0.94). Coarctation of the aorta contributed to this decline (OR, 0.55; 95% CI, 0.32-0.92). Atrial septal defect (ASD) (OR, 1.42; 95% CI, 1.13-1.80) and ASD with ventricular septal defect (OR, 1.52; 95% CI, 1.10-2.10) increased post-FAF. The remaining types of CHDs were unchanged. CONCLUSION: FAF alone does not have an impact on the prevalence of CHDs as a group and the majority of selected types of CHDs in Alberta. The decrease in LVOTO, particularly coarctation of the aorta, may be due to FAF or other environmental factors. The increase in ASD and ASD with ventricular septal defect may reflect an increase in diagnosis and ascertainment.

The Alberta Congenital Anomalies Surveillance System: a 40-year review with prevalence and trends for selected congenital anomalies, 1997-2019. / Le système de surveillance des anomalies congénitales de l'Alberta : compte rendu des données sur 40 ans avec prévalence et tendances de certaines anomalies congénitales entre 1997 et 2019.

INTRODUCTION: Current published long-term provincial or territorial congenital anomaly data are lacking for Canada. We report on prevalence (per 1000 total births) and trends in 1997-2019, in Alberta, Canada, for selected congenital anomalies. Associated risk factors are also discussed. METHODS: We used data from the Alberta Congenital Anomalies Surveillance System (ACASS) to calculate the prevalence and perform chi-square linear trend analyses. RESULTS: From 1997 to 2019, the overall prevalence of neural tube defects was stable, at 0.74 per 1000 total births. The same was true for spina bifida (0.38), orofacial clefts (1.99), more severe CHDs (transposition of the great arteries, 0.38; tetralogy of Fallot, 0.33; and hypoplastic left heart syndrome, 0.32); and gastroschisis (0.38). Anencephaly, cleft palate and anorectal malformation significantly decreased with a prevalence of 0.23, 0.75 and 0.54 per 1000 total births, respectively. Significantly increasing trends were reported for anotia/microtia (0.24), limb reduction anomalies (0.73), omphalocele (0.36) and Down syndrome (2.21) and for hypospadias and undescended testes (4.68 and 5.29, respectively, per 1000 male births). CONCLUSION: Congenital anomalies are an important public health concern with significant social and societal costs. Surveillance data gathered by ACASS for over 40 years can be used for planning and policy decisions and the evaluation of prevention strategies. Contributing genetic and environmental factors are discussed as is the need for continued surveillance and research.

Congenital heart defect case ascertainment by the Alberta Congenital Anomalies Surveillance System.

BACKGROUND: Congenital heart defects (CHDs) are the most common type of congenital anomaly, with a wide range of reported birth prevalence estimates. This quality assurance study describes CHD case ascertainment by the Alberta Congenital Anomalies Surveillance System (ACASS). METHODS: ACASS data for CHD cases were compared with additional sources including the two Pediatric Cardiology clinics in Alberta, the Alberta Children's Hospital Department of Pathology, and hospital records. Cases included live births, stillbirths, and fetal deaths at less than 20 weeks' gestation born in Alberta, Canada, between 1995 and 2002. The birth prevalence of cases and chi-square linear trend analyses were calculated for specific types of heart defects for the total study period. RESULTS: The ascertainment of CHD cases by ACASS was 45%. The total prevalence of CHD cases was 5.59 per 1000 total births (TBs; 95% confidence interval [CI], 5.32-5.86) when ACASS was the only data source and increased to 12.42 per 1000 TBs (95% CI, 12.03-12.83) when all data sources were used. Although the total prevalence of CHD cases remained stable during 1995 to 2002, the prevalence of atrial septal defect (ASD) and cases with an ASD and ventricular septal defect (VSD) significantly increased. The prevalence of left ventricular outflow tract obstruction cases significantly decreased during the study period. CONCLUSIONS: Pediatric cardiology clinics are worth including as additional ascertainment sources to contribute to more accurate prevalence estimates. The significant increases of ASD and cases with both an ASD and VSD may reflect differences in diagnostic and ascertainment practices.