Knowledge gap in genetic testing for autism

see Autism genetic testing: a qualitative study of awareness, attitudes, and experiences among parents of children with autism spectrum disorders

One of every 88 children born in the United States will be diagnosed with a form of autism, according to the US Centers for Disease Control and Prevention. Genetic testing for autism spectrum disorders (ASDs) has been available for a decade. However, the current rate of identifying an underlying genetic cause is less than 25%. In addition, genetic testing for ASDs raises issues of potential genetic discrimination, privacy concerns, and a potential psychological burden on parents and families. To assess current understanding and awareness of ASD genetic testing, Chen et al. conducted structured interviews with 42 parents of children diagnosed with autism. The research team recruited parents from community-based autism support groups in Texas to obtain a diverse ethnic and socioeconomic sample. Twelve parents in the sample had taken their child or children for genetic testing. Of the remainder, 63% had never heard of genetic testing for autism prior to the interview. Most of the parents (29 of 42) held positive attitudes about genetic testing, but 11 had negative attitudes, citing a variety of reasons. Most parents had learned about genetic testing through the mass media or scientific articles; only two interviewees had learned about ASD genetic testing from their children’s doctors. The authors advocate more education about autism genetic testing for both health-care providers and the public, as well as additional research to assess the influence of ethnic and socioeconomic status on attitudes toward genetic testing for autism. —Karyn Hede, News Editor

Single-gene defect, complex disease: explaining the disconnect

see Argininosuccinic aciduria: from a monogenic to a complex disorder

Ayelet Erez, winner of the 2012 William K. Bowes, Jr. Award in Medical Genetics, presents a review of complex phenotypes observed in inherited metabolic disorders, using the case of argininosuccinic aciduria (ASA) as a prototype. Erez, until recently a medical geneticist at Texas Children’s Hospital in Houston, has joined Israel’s Weizmann Institute, where she plans to establish a pediatric cancer genetic clinic. Her research has focused on understanding ASA, a rare inherited disorder caused by a defective gene necessary to make the enzyme argininosuccinate lyase (ASS1). Without the enzyme, the body can’t synthesize arginine, an essential amino acid. Her work using a mouse model of the disease helped establish that this single gene participated in more biological pathways than had previously been appreciated, including production of nitric oxide (NO), a known vasodilator. Patients with ASA can have chronic hypertension as a result. In her review, Erez shows how a single-gene defect can alter multiple metabolic pathways, leading to complex symptoms and predisposition to disease states. For example, although ASS1 contributes to the urea cycle in the liver, it is also expressed in other tissues, driven by the need for arginine in other metabolic pathways, including production of NO. Erez provides anecdotal evidence of a role for NO supplementation in treatment of some ASA patients and calls for a more nuanced understanding of interrelated metabolic pathways, with the goal of developing new treatments for inherited metabolic diseases. —Karyn Hede, News Editor