@article {365, title = {Diagnosis of Chronic Intestinal Pseudo-obstruction and Megacystis by Sequencing the ACTG2 Gene.}, journal = {J Pediatr Gastroenterol Nutr}, volume = {65}, year = {2017}, month = {2017 10}, pages = {384-387}, abstract = {

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.

}, keywords = {Actins, Adult, Child, Child, Preschool, Chronic Disease, Duodenum, Female, Fetal Diseases, Genetic Markers, Genetic Testing, Humans, Infant, Infant, Newborn, Intestinal Pseudo-Obstruction, Male, Mutation, Sequence Analysis, DNA, Urinary Bladder, Whole Exome Sequencing}, issn = {1536-4801}, doi = {10.1097/MPG.0000000000001608}, author = {Milunsky, Aubrey and Baldwin, Clinton and Zhang, Xiaoying and Primack, Daniel and Curnow, Adrian and Milunsky, Jeff} } @article {393, title = {Loss-of-Function Variants in MYLK Cause Recessive Megacystis Microcolon Intestinal Hypoperistalsis Syndrome.}, journal = {Am J Hum Genet}, volume = {101}, year = {2017}, month = {2017 Jul 06}, pages = {123-129}, abstract = {

Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a congenital disorder characterized by loss of smooth muscle contraction in the bladder and intestine. To date, three genes are known to be involved in MMIHS pathogenesis: ACTG2, MYH11, and LMOD1. However, for approximately 10\% of affected individuals, the genetic cause of the disease is unknown, suggesting that~other~loci are most likely involved. Here, we report on three MMIHS-affected subjects from two consanguineous families with~no~variants~in the known MMIHS-associated genes. By performing homozygosity mapping and whole-exome sequencing, we found~homozygous variants in myosin light chain kinase (MYLK) in both families. We identified a 7~bp duplication (c.3838_3844dupGAAAGCG~[p.Glu1282_Glyfs51]) in one family and a putative splice-site variant (c.3985+5C>A) in the other. Expression studies and splicing assays indicated that both variants affect normal MYLK expression. Because MYLK encodes an important kinase required for myosin activation and subsequent interaction with actin filaments, it is likely that in its absence, contraction of smooth muscle cells is impaired. The existence of a conditional-Mylk-knockout mouse model with severe gut dysmotility and abnormal function of the bladder supports the involvement of this gene in MMIHS pathogenesis. In aggregate, our findings implicate MYLK as a gene involved in the recessive form of MMIHS, confirming that this disease of the visceral organs is heterogeneous with a myopathic origin.

}, keywords = {Abnormalities, Multiple, Base Sequence, Colon, Female, Genes, Recessive, Homozygote, Humans, Intestinal Pseudo-Obstruction, Male, Mutation, Myosin-Light-Chain Kinase, Pedigree, Urinary Bladder}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.05.011}, author = {Halim, Danny and Brosens, Erwin and Muller, Fran{\c c}oise and Wangler, Michael F and Beaudet, Arthur L and Lupski, James R and Akdemir, Zeynep H Coban and Doukas, Michael and Stoop, Hans J and de Graaf, Bianca M and Brouwer, Rutger W W and van Ijcken, Wilfred F J and Oury, Jean-Fran{\c c}ois and Rosenblatt, Jonathan and Burns, Alan J and Tibboel, Dick and Hofstra, Robert M W and Alves, Maria M} } @article {416, title = {Visceral myopathy: Clinical and molecular survey of a cohort of seven new patients and state of the art of overlapping phenotypes.}, journal = {Am J Med Genet A}, volume = {170}, year = {2016}, month = {2016 11}, pages = {2965-2974}, abstract = {

Visceral motility dysfunction is a key feature of genetic disorders such as megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS, MIM moved from 249210 to 155310), chronic intestinal pseudo-obstruction (CIPO, MIM609629), and multisystemic smooth muscle dysfunction syndrome (MSMDS, MIM613834). The genetic bases of these conditions recently begun to be clarified with the identification of pathogenic variants in ACTG2, ACTA2, and MYH11 in individuals with visceral motility dysfunction. The MMIHS was associated with the heterozygous variant in ACTG2 and homozygous variant in MYH11, while the heterozygous variant in ACTA2 was observed in patients with MSMDS. In this study, we describe the clinical data as well as the molecular investigation of seven individuals with visceral myopathy phenotypes. Five patients presented with MMIHS, including two siblings from consanguineous parents, one had CIPO, and the other had MSMDS. In three individuals with MMIHS and in one with CIPO we identified heterozygous variant in ACTG2, one being a novel variant (c.584C>T-p.Thr195Ile). In the individual with MSMDS we identified a heterozygous variant in ACTA2. We performed the whole-exome sequencing in one sibling with MMIHS and her parents; however, the pathogenic variant responsible for her phenotype could not be identified. These results reinforce the clinical and genetic heterogeneity of the visceral myopathies. Although many cases of MMIHS are associated with ACTG2 variants, we suggest that other genes, besides MYH11, could cause the MMIHS with autosomal recessive pattern. {\textcopyright} 2016 Wiley Periodicals, Inc.

}, keywords = {Abnormalities, Multiple, Actins, Child, Preschool, Colon, Consanguinity, DNA Mutational Analysis, Fatal Outcome, Female, Genetic Association Studies, Humans, Infant, Infant, Newborn, Intestinal Pseudo-Obstruction, Male, Mutation, Phenotype, Polymorphism, Single Nucleotide, Treatment Outcome, Ultrasonography, Prenatal, Urinary Bladder}, issn = {1552-4833}, doi = {10.1002/ajmg.a.37857}, author = {Moreno, Carolina Araujo and Metze, Konradin and Lomazi, Elizete Aparecida and Bertola, D{\'e}bora Romeo and Barbosa, Ricardo Henrique Almeida and Cosentino, Viviana and Sobreira, Nara and Cavalcanti, Denise Pontes} } @article {257, title = {Heterozygous de novo and inherited mutations in the smooth muscle actin (ACTG2) gene underlie megacystis-microcolon-intestinal hypoperistalsis syndrome.}, journal = {PLoS Genet}, volume = {10}, year = {2014}, month = {2014 Mar}, pages = {e1004258}, abstract = {

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a rare disorder of enteric smooth muscle function affecting the intestine and bladder. Patients with this severe phenotype are dependent on total parenteral nutrition and urinary catheterization. The cause of this syndrome has remained a mystery since Berdon{\textquoteright}s initial description in 1976. No genes have been clearly linked to MMIHS. We used whole-exome sequencing for gene discovery followed by targeted Sanger sequencing in a cohort of patients with MMIHS and intestinal pseudo-obstruction. We identified heterozygous ACTG2 missense variants in 15 unrelated subjects, ten being apparent de novo mutations. Ten unique variants were detected, of which six affected CpG dinucleotides and resulted in missense mutations at arginine residues, perhaps related to biased usage of CpG containing codons within actin genes. We also found some of the same heterozygous mutations that we observed as apparent de novo mutations in MMIHS segregating in families with intestinal pseudo-obstruction, suggesting that ACTG2 is responsible for a spectrum of smooth muscle disease. ACTG2 encodes γ2 enteric actin and is the first gene to be clearly associated with MMIHS, suggesting an important role for contractile proteins in enteric smooth muscle disease.

}, keywords = {Abnormalities, Multiple, Actins, Adolescent, Adult, Child, Child, Preschool, Colon, Exome, Female, Heterozygote, Humans, Intestinal Pseudo-Obstruction, Male, Muscle, Smooth, Mutation, Urinary Bladder}, issn = {1553-7404}, doi = {10.1371/journal.pgen.1004258}, author = {Wangler, Michael F and Gonzaga-Jauregui, Claudia and Gambin, Tomasz and Penney, Samantha and Moss, Timothy and Chopra, Atul and Probst, Frank J and Xia, Fan and Yang, Yaping and Werlin, Steven and Eglite, Ieva and Kornejeva, Liene and Bacino, Carlos A and Baldridge, Dustin and Neul, Jeff and Lehman, Efrat Lev and Larson, Austin and Beuten, Joke and Muzny, Donna M and Jhangiani, Shalini and Gibbs, Richard A and Lupski, James R and Beaudet, Arthur} }