Hypertension and congenital aortic valve malformations are frequent causes of ascending aortic aneurysms. The molecular mechanisms of aneurysm formation under these circumstances are not well understood. Reference genes for gene activity studies in aortic tissue that are not influenced by aortic valve morphology and its hemodynamic consequences, aortic dilatation, hypertension, or antihypertensive medication are not available so far. This study determines genes in ascending aortic tissue that are independent of these parameters. Tissue specimens from dilated and undilated ascending aortas were obtained from 60 patients (age ≤70 years) with different morphologies of the aortic valve (tricuspid undilated n = 24, dilated n = 11; bicuspid undilated n = 6, dilated n = 15; unicuspid dilated n = 4). Of the studied individuals, 36 had hypertension, and 31 received ACE inhibitors or AT1 receptor antagonists. The specimens were obtained intraoperatively from the wall of the ascending aorta. We analyzed the expression levels of 32 candidate reference genes by quantitative RT-PCR (RT-qPCR). Differential expression levels were assessed by parametric statistics. The expression analysis of these 32 genes by RT-qPCR showed that EIF2B1, ELF1, and PPIA remained constant in their expression levels in the different specimen groups, thus being insensitive to aortic valve morphology, aortic dilatation, hypertension, and medication with ACE inhibitors or AT1 receptor antagonists. Unlike many other commonly used reference genes, the genes EIF2B1, ELF1, and PPIA are neither confounded by aortic comorbidities nor by antihypertensive medication and therefore are most suitable for gene expression analysis of ascending aortic tissue.

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TO THE EDITOR:We present a 43-year-old female patient with cytogenetically confirmed non-mosaic trisomy 21, hypothyroidism, and pericardial effusion. Down syndrome (trisomy 21) is the most common chromosomal anomaly, and since its life expectancy has increased beyond 50 years over the last decades [Wu and Morris, 2013], a mounting number of adult patients with Down syndrome seek treatment for somatic disease in routine clinical settings.Patients with Down syndrome have a higher prevalence of thyroid dysfunction, affecting 13-63% of individuals [Hardy et al., 2004]. Congenital hypothyroidism has been reported to be $28 times more common in newborns with Down syndrome than in controls [Fort et al., 1984;Patterson, 2009]. In the general population hypothyroidism can be complicated by pericardial effusion [Kabadi and Kumar, 1990;Hardy et al., 2004]. Echocardiographic studies on children have shown that individuals with Down syndrome have a significantly higher prevalence of isolated pericardial effusions compared to controls [Concolino et al., 2005]. However, it is still unclear whether the high prevalence of pericardial effusions in patients with Down syndrome is caused by hypothyroidism or if it should be considered an isolated finding. So far the association of pericardial effusion and hypothyroidism has repeatedly been reported in children [Martinez-Soto et al., 2010;Anah et al., 2011] but as yet only in two cases of male adults with Down syndrome [Said et al., 2007;Toorians and van Ekelen, 2007]. Pericardial effusions associated with hypothyroidism resolved after treatment with levothyroxine [Said et al., 2007;Toorians and van Ekelen, 2007;Martinez-Soto et al., 2010]. Evidence on the relationship between the two clinical conditions is still lacking in adults, especially in females with Down syndrome.A 43-year-old woman presented to the emergency room with a new onset of unspecific, breathing dependent chest pain and left sided shoulder pain, which had first occurred the night before. She had a medical history of recurrent pericardial effusions over the past 18 months, as well as long-standing hypothyroidism and hypoacusis. Her only medication was levothyroxine (75 mg daily). On physical examination she had normal heart sounds, no murmurs, and normal breathing sounds. Her heart rate was regular and her blood pressure 118/70 mmHg. Her abdomen was soft, non-tender, non-distended, and she had regular bowel sounds. Body temperature was normal (37.0˚C). She did not show any viral prodromal symptoms nor did she have any signs of volume-overload. Her ECG revealed a sinus rhythm with a heart rate of 64 beats per minute, no axis deviation, normal PR-, QRS-and QT-durations and no signs of acute ischemia, pericarditis or pericardial effusion. A transthoracic echocardiogram revealed a circumferential pericardial effusion with a maximum diameter of 22 mm in front of the right ventricle without apparent hemodynamic relevance. There were no signs of pulmonary hypertension, septal defects or other congenital cardiac abnormalitie...