Whole genome sequencing could become prenatal standard of care

By Piriya Mahendra, medwireNews Reporter

Whole genome sequencing of the DNA code of prenatal samples accurately and quickly identifies the location of chromosomal abnormalities, and could become a prenatal standard of care, researchers propose.

Whole genome sequencing enables the locations of chromosomal abnormalities to be identified within 14 days, which would enable physicians to predict the diagnosis of serious congenital disorders prenatally, counsel parents, and plan perinatal care, they say.

Unlike the current prenatal diagnostic methods of karyotyping and array comparative genomic hybridization (aCGH), whole genome sequencing provides the information required to detect "breakpoints" in the chromosomes at which rearrangements have occurred, and therefore determine the genomic regions altered.

Zehra Ordulu (Harvard Medical School, Boston, Massachusetts, USA) and team used whole genome sequencing to diagnose CHARGE syndrome, which is the leading cause of congenital deafblindness, in one of three prenatal samples they tested.

"Whole genome sequencing was consistent with a diagnosis of CHARGE syndrome, which was not possible based on prenatal imaging and the other commonly used prenatal genetic testing methods," remarked Ordulu as she presented her team's findings at the American Society of Human Genetics 2012 meeting in San Francisco, California, USA.

"This diagnosis would have changed medical care from an initial plan to repair an isolated heart defect to management of a morbid condition requiring immediate assessment of breathing and feeding difficulties."

Ordulu and team discovered a single disrupted gene in the other two prenatal samples analyzed using whole genome sequencing. In these cases, "whole genome sequencing reassured the parents that a known genomic syndrome is not associated with the single disrupted gene and provided valuable additional information to the historical risk assessment of an untoward outcome," she explained.

Lead author Cynthia Morton, also from Harvard Medical School, said: "Early detection of a genetic disorder is of significant importance for informing genetic counseling and for managing the pregnancy, birth, and further clinical follow-up.

"This study foretells an empowered prenatal diagnostic environment in which DNA sequencing becomes the standard of care."

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