Reading the Writing on the Genome

Researchers uncover mutations common to autism

By Mary J. Loftus

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gene analysts: Christa Lese Martin and Daniel Moreno De Luca are helping to link duplications or deletions on segments of DNA to a behavioral diagnosis of autism.

Kay Hinton

“15q11-13.” “16 p11.2.” Associate professor Christa Lese Martin, operations director of the Emory Genetics Laboratory, and postdoctoral fellow Daniel Moreno De Luca frequently speak in code as part of a team that produced a landmark result in autism genetics.

About thirty-five thousand genes make up the human genome. Martin and Moreno De Luca, along with their colleagues, helped to identify regions of the genome where mutations—in this case, duplications or deletions—exist that are implicated in autism.

About 30 to 40 percent of all autism can be given a genetic diagnosis, says Martin.

“Our study uses routine data from clinical labs to create a centralized database, showing frequencies, genotype, and phenotype data, and other relevant information from children with all different types of developmental disorders,” she says.

The data identified gains or losses on segments of DNA that were common to patients clinically diagnosed with autism.

The team made an intriguing find on a segment of chromosome 7. Deletion of the region is associated with Williams syndrome, in which individuals, although developmentally delayed, often exhibit “striking verbal abilities, highly social personalities, and an affinity for music.” Duplication of the same region, researchers found, is associated with autism.

Further studies should allow researchers to outline a network of genes whose activity is altered in people with autism.

“Most families just want to know what caused their child’s autism, and what they can do to help them,” Martin says.

Distinct genetic subtypes provide a greater degree of explanation for patients and families, a biological diagnosis that can guide families in future decision making and treatments. The genetic region affected can help identify associated disorders and clinical outcomes, and estimate the risk of recurrence in siblings.

Also, diagnostic genetic tests are beneficial because they can provide earlier, more accurate detection of autism in young children (it is hard to make a clinical diagnosis before age two).

Perhaps most important, families can get to know other families whose children have the same genetic diagnosis. “They can share information and recommend educational services or other therapies that worked for them,” Martin says.

Chromosomal microarray analysis, which can find much smaller chromosomal deletions and duplications, had the highest detection rate among clinically available genetic tests for patients with autism.

“Now, even pediatricians’ offices can offer genetic testing to families whose children are thought to have autism,” Martin says.

The main focus of the cytogenetics lab within the Genetics Laboratory is the identification and characterization of chromosomal imbalances involved in neurodevelopmental disorders. These include intellectual and developmental disabilities as well as autism.

New genetic counseling program

In addition to scientific research and analysis, Emory’s Department of Human Genetics is broadening services such as genetic counseling for families affected by such disorders.

The School of Medicine is launching a new Academic Health Professions program in genetic counseling. The two-year program combines cutting-edge coursework with multiple and varied clinical experiences. Graduates will receive a master of medical science in human genetics and genetic counseling.

Directed by Cecelia Bellcross, the program has received accreditation through the American Board of Genetic Counseling. Applications are open for the first class, which begins in summer 2012.

“The opportunity to create Georgia’s first genetic counseling training program has been a tremendous experience,” Bellcross says. “We are excited to offer a novel training program that is built upon the exceptional clinical, research, and laboratory expertise of the department faculty and staff, as well as genetic service providers throughout the greater Atlanta area. We are looking forward to training genetic counselors who will become leaders in this era of genomic medicine.”

While family history and genetic testing are increasingly becoming an integral part of medical care, there is a national shortage of board-certified genetic counselors who can help both the health care provider and the patient interpret genetic information related to risk, says Stephen Warren, chair of the Department of Human Genetics.

“Emory’s strong clinical and basic science activities in medical genetics will provide an ideal training environment,” Warren says.

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