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Casting a Wide Net: Whole-Exome Sequencing

November 1, 2013 7:00 am

A recent study shows that whole-exome sequencing can be used to diagnose genetic defects in patients with a range of phenotypes (NEJM 2013; 369: 1502-11).

In this study, the first 250 patients who had whole-exome sequencing performed at Baylor College of Medicine were studied.  80% had neurological problems and all had undergone previous extensive evaluation.

Results:

• The authors identified “86 mutated alleles that were highly likely to be causative in 62 patients (25%)”
• 83% of the autosomal dominant mutant alleles (n=33) and 40% of the X-linked mutant alleles (n=9) occurred de novo.
• In four patients, the authors identified multiple causative genes.  This may lead to a paradigm shift from Occam’s razor towards more cases of “multiple hits.”
• The authors speculate that the yield of this type of testing will improve as databases grow since many mutations at this time are of uncertain clinical significance

Bottomline: While this approach was used mainly in individuals with unexplained neurological problems, the use of whole-exome sequencing has broad potential.  In GI/Liver, the uses could include unexplained diarrheal disorders, metabolic/cholestatic liver disease, failure to thrive, inflammatory bowel disease, and many other conditions.

Related blog links:

• Understanding chromosomal microarrays | gutsandgrowth
• “It is never boring to be a physician” | gutsandgrowth

Posted by gutsandgrowth

Categories: Pediatrics

Tags: genetic mutations, whole-exome sequencing

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