To better understand parental opinions regarding the diagnostic process and use of genetic testing to assess risk for autism spectrum disorders (ASDs) in the younger siblings of affected children in the Unites States, we conducted a survey of parents who had at least one child with ASD. A total of 162 surveys were completed anonymously using an Internet-based survey tool. The mean reported time to ASD diagnosis and age at diagnosis were 35.2 months and 56.6 months, respectively. Seventy-two percent of parents felt there was a delay in diagnosis. Most parents indicated they would want to pursue genetic testing if a test were available that could identify risk in a younger sibling (80%). Earlier evaluation/intervention, closer monitoring, and lessened anxiety were reasons cited for testing. Our survey indicates most parents would pursue genetic risk assessment testing in children at high risk for ASD.
α-Actinins are actin-binding proteins that can be broadly divided into Ca(2+)-sensitive cytoskeletal and Ca(2+)-insensitive sarcomeric isoforms. To date, little is known about functional differences between the isoforms due to their indistinguishable activities in most in vitro assays. To identify functional differences in vivo between sarcomeric isoforms, we employed computational and molecular approaches to characterize the zebrafish (Danio rerio) genome, which contains orthologoues of each human α-actinin gene, including duplicated copies of actn3. Each isoform exhibits a distinct and unique pattern of gene expression as assessed by mRNA in situ hybridization, largely sharing similar expression profiles as seen in humans. The spatial conservation of expression of these genes from lower invertebrates to humans suggests that regulation and subsequent functions of these genes are conserved during evolution. Morpholino-based knockdown of the sarcomeric isoform, actn2, leads to skeletal muscle, cardiac, and ocular defects evident over the first week of development. Remarkably, despite the high degree of sequence conservation between actn2 and actn3, the phenotypes of α-actinin-2 deficient zebrafish can be rescued by overexpression of α-actinin-2 but not by α-actinin-3 mRNAs from zebrafish or human. These data provide functional evidence that the primary sequences of α-actinin-2 and α-actinin-3 evolved differences to optimize their functions.
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