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Diagnosis of Chronic Intestinal Pseudo-obstruction and Megacystis by Sequencing the ACTG2 Gene

Milunsky, Aubrey*,†; Baldwin, Clinton*; Zhang, Xiaoying*; Primack, Daniel*; Curnow, Adrian‡,§; Milunsky, Jeff*,†

Journal of Pediatric Gastroenterology & Nutrition: October 2017 - Volume 65 - Issue 4 - p 384–387
doi: 10.1097/MPG.0000000000001608
Original Articles: Gastroenterology

Objectives: The diagnosis of chronic intestinal pseudo-obstruction has depended on clinical features, manometry, and imaging. This report aimed to determine the efficacy of sequencing the actin γ-2 (ACTG2) gene for diagnosis. In addition, the goal was to determine how often a mutation would be found in our randomly collected cohort of probands and those probands published previously.

Methods: Whole exome sequencing was performed in 4 probands with chronic intestinal pseudo-obstruction. Subsequently, only the ACTG2 gene was sequenced in another 24 probands (total 28). We analyzed published data of 83 probands and our 28 (total 111) and determined how many had pathogenic variants and the precise genotype.

Results: Whole exome and Sanger sequencing revealed a pathogenic variant in the ACTG2 gene in 4 out of 28 of our probands and in 45 out of 83 published probands (49/111 [44.1%]). Moreover, a mutational hotspot in the ACTG2 gene was recognized. Genetic heterogeneity is evident.

Conclusions: Pooled gene sequencing results from 1 individual in each of 111 families enabled a precise diagnosis of an ACTG2 mutation in 49 (44%). The benefit to patients and families of early confirmation of a motility disorder not only helps avoid unnecessary intervention, but also enables institution of appropriate treatments and avoidance of secondary disorders such as malnutrition and poor growth. Knowledge of a pathogenic variant in a parent, with a 50% risk of recurrence, provides an opportunity for genetic counseling.

*Center for Human Genetics, Cambridge

Department of Obstetrics and Gynecology, Tufts University School of Medicine, Boston, MA

St. Luke's Regional Medical Center, Boise, ID

§University of Washington Center for Mendelian Genomics, Seattle, WA.

Address correspondence and reprint requests to Aubrey Milunsky, MD, DSc, Center for Human Genetics, 840 Memorial Dr, Suite 101, Cambridge, MA 02139 (e-mail: amilunsky@chginc.org).

Received 29 July, 2016

Accepted 26 February, 2017

The study was supported by Human Genome Research Institute and the National Heart, Lung, and Blood Institute grant U54HG006493.

The authors report no conflicts of interest.

© 2017 by European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology,