Concordance for the syndrome of autism in 40 pairs of afflicted twins

Abstract

The UCLA Registry for Genetic Studies in Autism was established in 1980 to test the hypothesis that genetic factors may be etiologically significant in subsets of patients. To date 61 pairs of twins have enrolled and 40 meet research diagnostic criteria for autism. The authors found a concordance for autism in these 40 pairs of 95.7% in the monozygotic twins (22 of 23) and 23.5% in the dizygotic twins (four of 17).

A Twin Study of Heritable and Shared Environmental Contributions to Autism

“…Twin studies have the potential to inform the relative contributions of genetic and environment factors to ASD etiology (Ronald and Hoekstra 2011). Early twin studies supported a strong genetic etiology to ASD (Bailey et al 1995; Folstein and Rutter 1977; Ritvo et al 1985; Steffenburg et al 1989). More recent diagnostic concordance studies have confirmed high monozygotic concordance for ASD (>88%), but also higher than previously appreciated dizygotic (>30%) and sibling (>15%) concordance rates (Ozonoff et al 2011; Rosenberg et al 2009; Taniai et al 2008).…”

Why We Should Study the Broader Autism Phenotype in Typically Developing Populations

“…The prominent role of genetics, rather than parenting, in both the etiology of ASD and the shared behavioral characteristics among family members took root with Folstein and Rutter's (1977) seminal article reporting higher concordance rates for ASD in monozygotic compared with same-sex dizygotic twins-a pattern that has been replicated in a number of subsequent twin studies (Bailey et al, 1995;Hallmayer et al, 2011;Le Couteur et al, 1996;Ritvo, Freeman, Mason-Brothers, Mo, & Ritvo, 1985). In addition, siblings have been found to have both an increased risk for ASD and elevated rates of autistic-like idiosyncrasies and communication disorders.…”

Practice Recommendations for Addressing Problem Behaviors in Siblings with Autism Spectrum Disorder

“…This topic warrants further investigation by researchers. Given the increasing prevalence of ASD and the fact that a sibling of a child with ASD is five times more likely to be affected with the diagnosis (Mason-Brothers, Mo, & Ritvo, 1985;Ritvo, Freeman, Mason-Brothers, Mo, & Ritvo, 1986;Bailey et al, 1995), it is likely that clinicians will increasingly encounter families dealing with the types of challenges described here. Thus, future research on how to best serve these families is warranted.…”

“…For example, Ozonoff et al (2011) found that 18.7% of siblings with one or more older siblings with ASD met diagnostic criteria themselves. In addition, twin studies have found a concordance rate for ASD of 60-95.7% in monozygotic twins but 0-23.5% in dizygotic twins (Mason-Brothers, Mo, & Ritvo, 1985;Ritvo, Freeman, Mason-Brothers, Mo, & Ritvo, 1986;Bailey et al, 1995). The combination of the heritability of ASD and the higher prevalence of problem behavior in individuals with ASD (Soke et al, 2016;Hill et al, 2014) means that there are likely many families with more than one child with ASD who also engages in challenging behaviors.…”