Biochemistry and Cell Biology
Copy number variation in fetal alcohol spectrum disorder
Journal: Biochemistry and Cell Biology
Manuscript ID bcb-2017-0241.R1
Manuscript Type: Article
Date Submitted by the Author: 09-Nov-2017
Complete List of Authors: Zarrei, Mehdi; The Centre for Applied Genomics Hicks, Geoffrey G.; University of Manitoba College of Medicine, Regenerative Medicine Reynolds, James N.; Queen's University School of Medicine, Biomedical and Molecular SciencesDraft Thiruvahindrapuram, Bhooma; The Centre for Applied Genomics Engchuan, Worrawat; Hospital for Sick Children SickKids Learning Institute Pind, Molly; University of Manitoba College of Medicine, Regenerative Medicine Lamoureux, Sylvia; The Centre for Applied Genomics Wei, John; The Centre for Applied Genomics Wang, Zhouzhi; The Centre for Applied Genomics Marshall, Christian R.; The Centre for Applied Genomics Wintle, Richard; The Centre for Applied Genomics Chudley, Albert; University of Manitoba Scherer, Stephen W.; The Centre for Applied Genomics
Is the invited manuscript for consideration in a Special Fetal Alcohol Spectrum Disorder Issue? :
Keyword: Fetal alcohol spectrum disorder, FASD, copy number variations, CNV
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1 Copy number variation in fetal alcohol spectrum disorder
2 Mehdi Zarrei,a Geoffrey G. Hicks,b James N. Reynolds,c,d Bhooma Thiruvahindrapuram,a
3 Worrawat Engchuan,a Molly Pind,b Sylvia Lamoureux,a John Wei,a Zhouzhi Wang,a Christian R.
4 Marshall,a Richard F. Wintle,a Albert E. Chudleye,f and Stephen W. Scherer,a,g
5 aThe Centre for Applied Genomics and Program in Genetics and Genome Biology, The Hospital
6 for Sick Children, Toronto, Ontario, Canada
7 bRegenerative Medicine Program, University of Manitoba, Winnipeg, Canada
8 cCentre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada. 9 dDepartment of Biomedical and MolecularDraft Sciences, Queen's University, Kingston, Ontario, 10 Canada
11 eDepartment of Pediatrics and Child Health, Max Rady College of Medicine, Rady Faculty of
12 Health Sciences, University of Manitoba, Winnipeg, Canada.
13 fDepartment of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady
14 Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
15 gDepartment of Molecular Genetics and McLaughlin Centre, University of Toronto, Toronto,
16 Ontario, Canada
17 Corresponding authors: Stephen W. Scherer ([email protected]) and Albert E.
18 Chudley ([email protected])
19
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20 Abstract: Fetal alcohol spectrum disorder (FASD) is characterized by a combination of
21 neurological, developmental, and congenital defects that may occur as a consequence of prenatal
22 alcohol exposure. Earlier reports showed that large chromosomal anomalies may link to FASD.
23 Here, we examined the prevalence and types of copy number variations (CNVs) in FASD cases
24 previously diagnosed by a multidisciplinary FASD team in sites across Canada. We genotyped
25 95 children with FASD and 87 age matched, typically developing controls on the Illumina
26 Human Omni2.5 SNP array platform. We compared their CNVs to those of 10,851 population
27 controls, in order to identify rare CNVs (<0.1% frequency), which may include large unbalanced
28 chromosomal abnormalities, that might be relevant to FASD. In 12/95 (13%) of the FASD cases,
29 rare CNVs were found that impact potentially clinically relevant developmental genes, including
30 the CACNA1H involved in epilepsy andDraft autism, the 3q29 deletion disorder, and others. Our
31 results show that a subset of children diagnosed with FASD have chromosomal deletions and
32 duplications that may co occur or explain the neurodevelopmental impairments in a diagnosed
33 cohort of FASD individuals. Children suspected to have FASD with or without sentinel facial
34 features of fetal alcohol syndrome and neurodevelopmental delays should potentially be
35 evaluated by a clinical geneticist and possibly have genetic investigations as appropriate to
36 exclude other etiologies.
37 Key words: Fetal alcohol spectrum disorder, FASD, copy number variations, CNV.
38 Résumé: [will be translated into French by the journal translator]
39 Mots clés: Fetal alcohol spectrum disorder, FASD, copy number variations, CNV.
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40 Introduction
41 Fetal alcohol spectrum disorder (FASD) is an umbrella term for a group of alcohol related
42 disorders, characterizing the full range of damage from prenatal alcohol exposure (Chudley et al.
43 2005). It comprises fetal alcohol syndrome (FAS), partial FAS, alcohol related
44 neurodevelopmental disorders, and alcohol related birth defects, which are congenital anomalies
45 that can include growth deficits, facial dysmorphism, and/or malformations in multiple
46 physiological systems (Abdelmalik et al. 2013; Chudley et al. 2005; Douzgou et al. 2012;
47 Popova et al. 2016). FASD is also associated with numerous co morbid neurodevelopmental
48 disorders, including intellectual disabilities, microcephaly, autism spectrum disorder (ASD), and
49 attention deficit hyperactivity disorder (Abdelmalik et al. 2013; Douzgou et al. 2012; Weyrauch
50 et al. 2017). Draft
51 The reported incidence of FASD is 0.2 to 3.0 per 1,000 live births for most countries (Douzgou
52 et al. 2012). However, an incidence of up to 89.2 per 1,000 births was reported in regions of
53 South Africa where wine production is abundant (May et al. 2007). A recent review of the
54 global prevalence of FASD in children and youth reported a prevalence of 7.7 per 1000
55 population (95% CI, 4.9 11.7 per 1000 population). The highest rate was reported by the World
56 Health Organization European region with 19.8 per 1000 population, (95% CI, 14.1 28 per 1000
57 population)(Lange et al. 2017).
58 It is well established in the medical community that not all children exposed to alcohol
59 prenatally develop FASD (Abel 1995; Stoler 1999). This indicates that factors other than
60 prenatal alcohol exposure also contribute to FASD aetiology. The impact of the genetic
61 variations to the aetiology of FASD has been studied in animal models (reviewed in (Eberhart
62 and Parnell 2016; McCarthy and Eberhart 2014)). However, genetic studies on human are
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63 restricted to case reports with large chromosomal anomalies (Stoler 1999) and twin studies
64 (Chasnoff 1985). For example, association of trisomy 21 or ring chromosome 6 with FASD has
65 been reported (Bingol et al. 1987; Muller et al. 1993; Romke et al. 1987). Large chromosomal
66 anomalies such as 22q11.2 microdeletion and microduplication, and 1q21 microduplications,
67 among others, were reported in 9% (7/90) of cases with FASD in a UK cohort (Douzgou et al.
68 2012). A retrospective study of younger and older siblings of patients with FAS clearly indicated
69 a greatly increased risk of FAS in younger siblings if an older sibling had been diagnosed with
70 FAS (Abel 1988). The contribution of CNVs to the aetiology of neurodevelopmental disorders
71 (Gazzellone et al. 2016; Lionel et al. 2011; Oskoui et al. 2015; Pinto et al. 2014; Pinto et al.
72 2010; Zarrei et al. 2017a), including those that may be comorbid with FASD (Popova et al.
73 2016), has been well documented. However,Draft until the current study, a genome wide CNV
74 analysis in FASD cases had not been performed.
75 Our objective was to assess the role of CNVs and chromosomal abnormalities, at a genome
76 wide level, in a clinically well defined collection of individuals with FASD, to further define
77 genomic risk contribution in this common disorder.
78 Materials and methods
79 Participants
80 Ninety five children diagnosed with FASD and eighty seven aged matched, typically
81 developing controls as internal control were recruited through the NeuroDevNet Canadian FASD
82 study cohort (Portales Casamar et al. 2016; Reynolds et al. 2011) and the majority of clinical
83 centers used the Canadian FASD Guidelines for diagnosis (Chudley et al. 2005). Siblings of
84 some probands, if consented, were also recruited for this study (Table S1). Our FASD cases have
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85 a sex ratio of 0.73 (male: 40; female: 55; Table S1; 0.85 in internal controls). Research Ethics
86 Board approval was obtained from each participating centre, and all caregivers and participants
87 provided written informed consent. Saliva samples were collected from the children. Details of
88 saliva collection and storage is provided elsewhere (Portales Casamar et al. 2016).
89 Genotyping, CNV calling, and detection of rare variants
90 DNA extracted from saliva using standard protocols was genotyped on two Illumina Human
91 Omni2.5 SNP array platforms (Omni2.5m Quad; n=132 and Omni2.5m 8; n=50) at The Centre
92 for Applied Genomics in Toronto according to the manufacturer’s protocol. Relevant microarray
93 data are deposited in the Gene Expression Omnibus (https://www.ncbi.nlm.nih.gov/geo/; 94 GSE102650). Quality control and ancestryDraft assessment procedures were as described previously 95 (Gazzellone et al. 2016; Oskoui et al. 2015). Ancestry was determined using PLINK v1.07
96 (Purcell et al. 2007).
97 CNV calling was performed as previously described with slight modifications (Oskoui et al.
98 2015). In brief, three CNV calling algorithms were used for both cases and internal controls: i.e.
99 iPattern (Pinto et al. 2011), PennCNV (Wang et al. 2007), and QuantiSNP (Colella et al. 2007).
100 We then analyzed “stringent” CNVs, those detected by at least two methods. Detecting large
101 CNVs particularly sex chromosomal aneuploidies is challenging (Oskoui et al. 2015). Hence,
102 these large CNVs are sometimes fragmented. If found, they were merged and their identity
103 confirmed by examining the probe density and B allele frequencies in the region.
104 We identified rare CNVs as those at not more than 0.1% frequency among 10,851 population
105 control samples (explained in detail in (Zarrei et al. 2017a)), using a 50% reciprocal overlap
106 strategy (Conrad et al. 2010; Redon et al. 2006). This list was further restricted with those that
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107 are not present in the study internal controls, which are age matched to the cases. We
108 additionally removed those with less than 75% overlap with copy number stable regions,
109 according to our stringent CNV map of the human genome (Zarrei et al. 2015). We investigated
110 CNVs > 20kb and covered by ≥ 5 consecutive probes (Mosca et al. 2016). Validation of relevant
111 CNVs to FASD was performed by TaqMan Copy Number Assays. The resulting list of all CNVs
112 is shown in Table S1. The genomic coordinates used are based on Human Genome Build
113 GRCh37/hg19.
114 Searching for CNVs deemed relevant to FASD
115 We investigated CNVs impacting coding sequence of our FASD genes or those implicated in 116 other neurodevelopmental disorders (YuenDraft et al. 2017; Yuen et al. 2016; Yuen et al. 2015). We 117 also examined OMIM genes with neurological function or other functions that may be congruent
118 with FASD physiology. Our FASD gene list comprises the top 30 genes differentially methylated
119 in children with FASD (Portales Casamar et al. 2016), top ranked genes identified using binary
120 matrix filtering (Lombard et al. 2007), and genes involved in alcohol metabolism in humans and
121 human homologues of those with established interactions with alcohol in animal models
122 (Eberhart and Parnell 2016). CNVs in regions associated with known genomic disorders
123 including DECIPHER syndrome loci (Firth et al. 2009) and ClinGen loci (Rehm et al. 2015),
124 were also analyzed. All CNV data was also compared to population control data in the Database
125 of Genomic Variants (MacDonald et al. 2014).
126 Gene-set burden enrichment analysis and burden of pLI scores
127 Gene sets with an a priori association to neuropsychiatric disorders were compiled following
128 methods described elsewhere (Marshall et al. 2017; Merico et al. 2015) (Table S2). We also
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129 included a protein