Monoamniotic monochorionic twins discordant for noncompaction cardiomyopathy

Abstract

Occasionally “identical twins” are phenotypically different, raising the question of zygosity and the issue of genetic versus environmental influences during development. We recently noted monochorionic-monoamniotic twins, one of which had an isolated cardiac abnormality, noncompaction cardiomyopathy, a condition characterized by cardiac ventricular hypertrabeculation. We examined the prenatal course and subsequent pathologic correlation since ventricular morphogenesis may depend on early muscular contraction and blood flow. The monochorionic-monoamniotic female twin pair was initially identified since one fetus presented with increased nuchal translucency. Complete heart block was later identified in the fetus with nuchal translucency who did not survive after delivery. In contrast, the unaffected twin had normal cardiac studies both prenatally and postnatally. Pathologic analysis of the affected twin demonstrated noncompaction of the left ventricle with dysplasia of the aortic and pulmonary valves. Dissection of the cardiac conduction system disclosed atrioventricular bundle fibrosis. Maternal lupus studies, amniocentesis with karyotype, and studies for 22q11.2 were normal. To test for zygosity, we performed multiple STR marker analysis and found that all markers were shared even using non-blood tissues from the affected twin. These studies demonstrate that monozygotic twins that are monochorionic monoamniotic can be discordant for cardiac noncompaction. The results suggest further investigation into the potential roles of pathologic fibrosis, contractility, and blood flow in cardiac ventricle development.

Non-Compaction Left Ventricle Myocardium: A Symptom, Syndrome or Development Variation?

“…Во-вторых, слой некомпакт-ного миокарда располагается всегда эндокардиально, что соответствует направлению компактизации "сна-ружи вовнутрь". В-третьих, многочисленные описа-ния диагностики СНМЛЖ внутриутробно и у ново-рожденных не позволяют предположить развитие НМЛЖ вследствие длительно текущей кардиомиопа-тии [13][14][15][16]. Известно большое число генов, контролирующих эмбриогенез сердца, однако их точная роль в процес-сах компактизации миокарда в эмбриональном пери-оде изучена недостаточно.…”

Implications of genetic testing in noncompaction/hypertrabeculation

“…Pedigrees have been a cornerstone for evaluating families [Bennett et al, 2008], and they are essential in evaluation for cardiomyopathies [Morales et al, 2008]. Noncompaction/hypertrabeculation has been seen in concordant twins [Ali, 2008; Peters et al, 2012], in discordant twins [Ng et al, 2013], and in families with other cardiomyopathies or cardiac disease [Budde et al, 2007; Dellefave et al, 2009]. Evidence for familial disease, consanguinity [Shieh et al, 2012] or specific inheritance patterns should be examined thoroughly [Hoedemaekers et al, 2010].…”

Response to Finsterer and Stöllberger “Explanations for discordance of noncompaction in monozygotic twins”

“…To our knowledge, there has been no evidence of heart dysfunction in the living twin [Ng et al, 2013] and the family will be followed.We agree that the definition of noncompaction is an interesting and unsettled issue. Finsterer and Stollberger [2015] for their comments in their letter in this issue.…”

“…Finsterer and Stollberger [2015] for their comments in their letter in this issue. To our knowledge, there has been no evidence of heart dysfunction in the living twin [Ng et al, 2013] and the family will be followed.We agree that the definition of noncompaction is an interesting and unsettled issue. We provide here a reference regarding underdeveloped papillary muscles in cases [Burke et al, 2005].…”

“…Finsterer and Stollberger [2015] for their comments in their letter in this issue. To our knowledge, there has been no evidence of heart dysfunction in the living twin [Ng et al, 2013] and the family will be followed.…”