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      Combined obstructive hypertrophic cardiomyopathy and double outlet right ventricle in an infant with Down syndrome

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          Abstract

          Patient: Male, 2

          Final Diagnosis: Obstructive hypertrophic cardiomyopathy

          Symptoms: Congestive heart failure

          Medication: —

          Clinical Procedure: Left ventricular septal myectomy • repair of congenital heart disease

          Specialty: Cardiology

          Objective:

          Rare disease

          Background:

          Hypertrophic cardiomyopathy (HCM) is uncommon in Down syndrome (DS). When combined with congenital heart disease (CHD) both morbidity and mortality may be greater compared to CHD alone. Whether HCM in DS patients is related to having trisomy 21 versus a second site mutation is unknown.

          Case Report:

          We report a case of severe HCM in an infant with DS in combination with double outlet right ventricle (DORV) who required surgery for relive of sub-aortic obstruction and congestive heart failure. We predicted that this infant would have a second site mutation involving either a sarcomeric protein or metabolic disorder as a cause for his HCM. Using current genetic and metabolic testing as well as histologic assessment of excised cardiac tissue we sought to further characterize the nature of the HCM. A successful resection of sub-aortic stenosis and DORV repair was performed. Genetic and metabolic testing was negative for gene defects and/or syndromes commonly associated with familial HCM. Excised cardiac tissue from the ventricular septum exhibited myocyte hypertrophy and sub-endocardial fibrosis but no sarcomeric disarray, myocyte fibrosis or glycogen storage. Metabolic testing for common forms of mitochondrial disease was negative. Post-operative echocardiograms show persistent, non-obstructive septal hypertrophy.

          Conclusions:

          Unlike prior reports, this child required a surgical intervention to relieve his sub-aortic obstruction. Thus, HCM in this population can be more serious that previously suspected. Although testing did not reveal the cause of his HCM, we still suggest screening for known causes of HSC until the etiology of the HCM in DS is well understood.

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          Most cited references20

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          DSCR1, overexpressed in Down syndrome, is an inhibitor of calcineurin-mediated signaling pathways.

          Down syndrome is one of the major causes of mental retardation and congenital heart malformations. Other common clinical features of Down syndrome include gastrointestinal anomalies, immune system defects and Alzheimer's disease pathological and neurochemical changes. The most likely consequence of the presence of three copies of chromosome 21 is the overexpression of its resident genes, a fact which must underlie the pathogenesis of the abnormalities that occur in Down syndrome. Here we show that DSCR1, the product of a chromosome 21 gene highly expressed in brain, heart and skeletal muscle, is overexpressed in the brain of Down syndrome fetuses, and interacts physically and functionally with calcineurin A, the catalytic subunit of the Ca(2+)/calmodulin-dependent protein phosphatase PP2B. The DSCR1 binding region in calcineurin A is located in the linker region between the calcineurin A catalytic domain and the calcineurin B binding domain, outside of other functional domains previously defined in calcineurin A. DSCR1 belongs to a family of evolutionarily conserved proteins with three members in humans: DSCR1, ZAKI-4 and DSCR1L2. We further demonstrate that overexpression of DSCR1 and ZAKI-4 inhibits calcineurin-dependent gene transcription through the inhibition of NF-AT translocation to the nucleus. Together, these results suggest that members of this newly described family of human proteins are endogenous regulators of calcineurin-mediated signaling pathways and as such, they may be involved in many physiological processes.
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            Down syndrome suppression of tumor growth and the role of the calcineurin inhibitor DSCR1

            The incidence of many cancer types is significantly reduced in individuals with Down syndrome1–4 and it is proposed that this broad cancer protection is conferred by the elevated expression of one or more of the 231 supernumerary genes on the extra copy of chromosome 21. One such gene is the Down syndrome candidate region-1 (Dscr1, RCAN1), which encodes a protein that suppresses vascular endothelial growth factor (VEGF)-mediated angiogenic signalling via the calcineurin pathway5–10. Here we show that DSCR1 is elevated in Down syndrome individuals and a mouse model of Down syndrome. Further, we show that the modest elevation in expression afforded by a single extra transgenic copy of Dscr1 is sufficient to confer significant suppression of tumor growth in mice and that such resistance is a consequence of a deficit in tumor angiogenesis arising from suppression of the calcineurin pathway. We also provide evidence that attenuation of calcineurin activity by DSCR1 together with another chromosome 21 gene DYRK1A, may be sufficient to dramatically diminish angiogenesis. These data provide a mechanism for the reduced cancer incidence in Down syndrome and identifies the calcineurin signalling pathway and its regulators DSCR1 and DYRK1A as potential therapeutic targets in cancers arising in all individuals.
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              Is Open Access

              Gene expression in cardiac tissues from infants with idiopathic conotruncal defects

              Background Tetralogy of Fallot (TOF) is the most commonly observed conotruncal congenital heart defect. Treatment of these patients has evolved dramatically in the last few decades, yet a genetic explanation is lacking for the failure of cardiac development for the majority of children with TOF. Our goal was to perform genome wide analyses and characterize expression patterns in cardiovascular tissue (right ventricle, pulmonary valve and pulmonary artery) obtained at the time of reconstructive surgery from 19 children with tetralogy of Fallot. Methods We employed genome wide gene expression microarrays to characterize cardiovascular tissue (right ventricle, pulmonary valve and pulmonary artery) obtained at the time of reconstructive surgery from 19 children with TOF (16 idiopathic and three with 22q11.2 deletions) and compared gene expression patterns to normally developing subjects. Results We detected a signal from approximately 26,000 probes reflecting expression from about half of all genes, ranging from 35% to 49% of array probes in the three tissues. More than 1,000 genes had a 2-fold change in expression in the right ventricle (RV) of children with TOF as compared to the RV from matched control infants. Most of these genes were involved in compensatory functions (e.g., hypertrophy, cardiac fibrosis and cardiac dilation). However, two canonical pathways involved in spatial and temporal cell differentiation (WNT, p = 0.017 and Notch, p = 0.003) appeared to be generally suppressed. Conclusions The suppression of developmental networks may represent a remnant of a broad malfunction of regulatory pathways leading to inaccurate boundary formation and improper structural development in the embryonic heart. We suggest that small tissue specific genomic and/or epigenetic fluctuations could be cumulative, leading to regulatory network disruption and failure of proper cardiac development.
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                Author and article information

                Journal
                Am J Case Rep
                Am J Case Rep
                amjcaserep
                The American Journal of Case Reports
                International Scientific Literature, Inc.
                1941-5923
                2013
                01 November 2013
                : 14
                : 453-458
                Affiliations
                [1 ]Department of Pediatrics, University of Kansas Medical Center, Kansas City, KS, U.S.A.
                [2 ]Department of Pathology, University of Kansas Medical Center, Kansas City, KS, U.S.A.
                [3 ]Department of Pediatrics, Division of Cardiology, University of Kansas Medical Center, Kansas City, KS, U.S.A.
                Author notes

                Authors’ Contribution:

                [A]

                Study Design

                [B]

                Data Collection

                [C]

                Statistical Analysis

                [D]

                Data Interpretation

                [E]

                Manuscript Preparation

                [F]

                Literature Search

                [G]

                Funds Collection

                Corresponding Author: Valerie A. Schroeder, e-mail: vschroeder@ 123456kumc.edu
                Article
                889581
                10.12659/AJCR.889581
                3821707
                3a58ce89-4f21-4cf0-9ef2-8090d61b2e6d
                © Am J Case Rep, 2013

                This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License

                History
                : 18 July 2013
                : 06 August 2013
                Categories
                Articles

                conal-truncal defect,hypertrophic cardiomyopathy,down syndrome

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