ACTG2 Variants in Pediatric Chronic Intestinal Pseudo-obstruction With Megacystis

Abstract

Background/aims: Chronic intestinal pseudo-obstruction (CIPO) is a clinically heterogeneous syndrome characterized by compromised peristalsis and intestinal obstruction. Variants of actin gamma 2 (ACTG2), a protein crucial for correct enteric muscle contraction, have been found in CIPO patients. The aim of this study is to examine the clinical features and ACTG2 variants in Korean patients with CIPO.

Methods: From January 1995 to August 2020, 12 patients diagnosed with CIPO were included and genetic analysis testing of ACTG2 was performed.

Results: Heterozygous ACTG2 missense variants were found in 6 patients (50.0%). The p.Arg257Cys variant was found in 3 patients, and p.Arg63Gln and p.Arg178His variants were found in 1 patient each. A novel variant, p.Ile193Phe, was found in 1 patient. Three patients were diagnosed at birth, 2 at the age of 1 year, and 1 at 3 years of age. Abnormal prenatal genitourinary ultrasonographic findings were found in all 6 patients; microcolon was found in 4 patients (66.7%), and megacystis in all 6 patients. The pathology showed abnormal ganglion cells as well as myopathic findings. All patients are dependent on total parenteral nutrition and are to date alive.

Conclusions: ACTG2 variants are commonly found in Korean patients with CIPO. In CIPO patients with megacystis and abnormal prenatal ultrasonography, genetic testing of ACTG2 should be considered. Molecular diagnosis of CIPO is more important than pathologic diagnosis.

Keywords: ACTG2; Intestinal pseudo-obstruction; Megacystis; Visceral myopathy.

Figure

Pathologic findings of patients with ACTG2 variants. (A) [Case 1] The inner circular muscle layer shows nuclear palisading (arrows). (B) [Case 2] The inner circular muscle layer shows vacuolar change (arrow). (C) [Case 3] The outer layer of the muscle shows acidophilic globular bodies (arrows). (D) [Case 5] The outer muscle layer shows marked thinning (arrows) (H&E, bar = 0.1 mm).