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.Another indication of the genetic or epigenetic nature of autism.
Wednesday, October 7, 2009
A study in the Archives of Pediatrics & Adolescent Medicine looked at 210 dizygotic (DZ) twin pairs and 67 monozygotic (MZ). All were under 18 and had at least one twin diagnosed with autism spectrum disorder (ASD).