Characteristics and Concordance of Autism Spectrum Disorders Among 277 Twin Pairs

Department of Medical Informatics, Kennedy Krieger Institute, Baltimore, MD 21211, USA.
JAMA Pediatrics (Impact Factor: 5.73). 10/2009; 163(10):907-14. DOI: 10.1001/archpediatrics.2009.98
Source: PubMed


To examine patterns of autism spectrum disorder (ASD) inheritance and other features in twin pairs by zygosity, sex, and specific ASD diagnosis.
Cross-sectional study.
Internet-based autism registry for US residents.
Survey results from 277 twin pairs (210 dizygotic [DZ] and 67 monozygotic [MZ]) aged 18 years or younger with at least 1 affected twin.
Zygosity and sex.
Concordance within twin pairs of diagnosis, natural history, and results from standardized autism screening.
Pairwise ASD concordance was 31% for DZ and 88% for MZ twins. Female and male MZ twins were 100% and 86% concordant, respectively, and DZ twin pairs with at least 1 female were less likely to be concordant (20%) than were male-male DZ twin pairs (40%). The hazard ratio for ASD diagnosis of the second twin after a first-twin diagnosis was 7.48 for MZ vs DZ twins (95% confidence interval, 3.8-14.7). Affected DZ individual twins had an earlier age at first parental concern and more frequent diagnoses of intellectual disability than did MZ twins; MZ twins had a higher prevalence of bipolar disorder and Asperger syndrome and higher concordance of the latter. Results of autism screening correlated with parent-reported ASD status in more than 90% of cases.
Our data support greater ASD concordance in MZ vs DZ twins. Overall higher functioning, psychiatric comorbidity, and Asperger syndrome concordance among affected MZ vs DZ twins may also suggest differential heritability for different ASDs. For families in which one MZ twin is diagnosed with ASD, the second twin is unlikely to receive an ASD diagnosis after 12 months. In addition, Internet parent report of ASD status is valid.

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Available from: Rebecca E Rosenberg, Oct 15, 2015
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    • "This is because the primary differences between MZ and DZ twins, aside from nonshared factors (e.g., experiences outside the home, friends, etc.), are genetically mediated. Twin studies to date yield heritability estimates of ASD between 70 and 80% [27] [28] [29]. Aside from one recent study suggesting a significant contribution of shared environmental factors to ASD (experiences that are common to both twins, e.g., socioeconomic status and parental mental health problems [4]), these studies have generally reported small or nonsignificant shared environmental effects. "
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    BioMed Research International 08/2015; 2015:672784. DOI:10.1155/2015/672784 · 2.71 Impact Factor
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    • "( Fombonne , 2003 ) and affects approximately 1% of the population ( Centers for Disease Control and Prevention , 2012 ) . Recent studies have provided overwhelming evidence for genetic involvement in ASD ( Bishop , Maybery , Wong , Maley , & Hallmayer , 2006 ; Constantino et al . , 2006 ; Constantino , Zhang , Frazier , Abbacchi , & Law , 2010b ; Rosenberg et al . , 2009 ; Taniai , Nishiyama , Miyachi , Imaeda , & Sumi , 2008 ; Veenstra - VanderWeele , Christian , & Cook , 2004 ) . The risk of having a child with ASD increases with a family history of ASD , with heritability estimates ranging between 37% and 70% ( Constantino et al . , 2013 ; Hallmayer et al . , 2011 ) . First degree relatives of childr"
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    ABSTRACT: Head circumference growth in individuals with an Autism Spectrum Disorder (ASD) has been well characterized in the first two to three years of life and reflects a period of acceleration followed by a period of deceleration when compared with their typically developing (TD) peers. While this altered growth trajectory has been consistently found for head circumference, it is less clear if an abnormal growth trajectory also exists across measures of height and weight. Moreover, most studies have focused on infancy and early childhood, and no longitudinal data have been collected in older children with ASD. This review focuses on the physical growth trajectory of individuals with ASD, and proposes that a general growth dysregulation is present in ASD, and that an endophenotype within ASD may exist that is characteristic of extreme overgrowth. Two possible explanations for a general growth dysregulation are suggested: (1) a connective tissue disorder, which is frequently associated with increased height and disproportionate body ratios; and (2) a dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, which regulates growth hormones. The existence of a general growth dysregulation, and possible endophenotype, may serve as a potential biological marker in ASD.
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    • "The measured ASD monozygote concordance rate using the IAN database varies from 41/60 = 0.683 (2014) to 59/67 = 0.881[2] or somewhere between 68.3% and 88.1%. What does the multimutation model predict the monozygote concordance rate to be? "
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