A powerful new genetic test that scans for rare childhood diseases is providing faster and more conclusive results than ever before. The test examines the entire genome to identify the single gene mutation that led to the disorder.

When Calvin Lapidus was eight months old, his mother Audrey suspected he was not developing normally, even though his doctors said he was.

By eight months he wasnt sitting up on his own," she recalled. "He wasnt rolling over on his own and he was just missing his milestones.

A frantic odyssey to learn what was wrong led the family to the Clinical Genomics Center at the University of California Los Angeles. The Center had just introduced a test called exome sequencing, an analysis of the entire genome at once, instead of gene by gene. Calvin was its first patient, said Stanley Nelson, a UCLA professor of human genetics and pathology and laboratory medicine.

He described the typical scenario: Children come in with a set of symptoms, a set of problems, a set of issues, and its very difficult for physicians to say which one of 5,000 diseases this patient has.

Some conditions are so rare that a physician may have only seen a few, if any, cases in his or her practice.

Sequencing DNA

The team at the Center extracted and sequenced DNA from blood samples from Calvin and his parents. Then they scanned all the genes simultaneously to find the single mutation that caused the disorder.

Nelson said that on average every location in the genome is examined and re-examined 100 times.

What that means is that we see 50 of the DNA variants that you got from your mom," he said. "We see 50 of the DNA variants that you got from your dad at every single base position in the exome, or in the protein coating part of the genome.

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New Genetic Test Diagnoses Rare Childhood Diseases