Papers by Roxanne Gendron
In humans, chromosome-number abnormalities have been associated with altered recombination and in... more In humans, chromosome-number abnormalities have been associated with altered recombination and increased maternal age. Therefore, age-related effects on recombination are of major importance, especially in relation to the mechanisms involved in human trisomies. Here, we examine the relationship between maternal age and recombination rate in humans. We localized crossovers at high resolution by using over 600,000 markers genotyped in a panel of 69 French-Canadian pedigrees, revealing recombination events in 195 maternal meioses. Overall, we observed the general patterns of variation in fine-scale recombination rates previously reported in humans. However, we make the first observation of a significant decrease in recombination rates with advancing maternal age in humans, likely driven by chromosome-specific effects. The effect appears to be localized in the middle section of chromosomal arms and near subtelomeric regions. We postulate that, for some chromosomes, protection against no...
Map to Chromosome 10P15
Familial ventricular aneurysms and septal defects
Univei-sité de Montréal Évaluation d'un modèle iii vitro dans l'étude des effets d'un apport supp... more Univei-sité de Montréal Évaluation d'un modèle iii vitro dans l'étude des effets d'un apport supplémentaire de cystéïne chez le nouveau-né humain par
Aortic Isthmus Flow Recording Predicts the Outcome of the Recipient Twin after Laser Coagulation in Twin-Twin Transfusion Syndrome
Fetal Diagnosis and Therapy
Ultrasound in Obstetrics & Gynecology, 2016
Objectives As postnatal identification of accelerated idioventricular rhythm (AIVR) relies on spe... more Objectives As postnatal identification of accelerated idioventricular rhythm (AIVR) relies on specific electrocardiographic patterns, prenatal diagnosis of this condition is challenging and its true incidence is unknown. The objectives of this study were to evaluate the performance of prenatal ultrasonography in identifying intrauterine cardiocirculatory events linked to specific electrocardiographic signs of postnatal AIVR, including left or right ventricular origin, and to assess the prenatal prognosis of this arrhythmia. Methods We reviewed Doppler tracings from the superior vena cava/ascending aorta (SVC/Ao), ductus venosus (DV), ductus arteriosus (DA) and aortic isthmus (AoI), as well as simultaneous M-mode recordings of septal and left ventricular wall motions of fetuses diagnosed with AIVR from January 2004 to December 2014. Results Three cases of AIVR were identified among 27 912 fetuses. SVC/Ao Doppler flow recordings revealed atrioventricular dissociation (ventricular rates within 20% of atrial rates) in all three fetuses and episodes of isorhythmic atrioventricular dissociation in one, while M-mode confirmed normal left ventricular shortening fraction in all cases. Fusion beats were observed on AoI tracing in one fetus, while simultaneous recordings of AoI and DA revealed signs of right bundle branch block in one case and left bundle branch block in the other two. On DV Doppler recordings, retrograde a-waves in the presence of simultaneous atrial and ventricular contractions were observed in all three fetuses, leading to an increase in
Ventricular outputs, central blood flow distribution and flow pattern through the aortic isthmus of fetuses with simple transposition of the great arteries
Acta Obstetricia et Gynecologica Scandinavica, 2016
Our objective was to determine the impact of simple transposition of the great arteries (TGA) on ... more Our objective was to determine the impact of simple transposition of the great arteries (TGA) on fetal left ventricular (LV) and right ventricular (RV) performances and central circulatory dynamics including the aortic isthmus. Ventricular stroke volumes were calculated as the product of the cross-sectional area of the corresponding semi-lunar valve and the flow velocity integral through these valves. Volume flow in ductus arteriosus (QDA ) was evaluated using the same technique. Flow through the lungs (QLUNGS ) was calculated by subtracting net QDA from flow in main pulmonary artery [net QDA = QDA minus retrograde ductus arteriosus (DA) diastolic flow]. Relative performance of each ventricle expressed as percentage of combined cardiac output was also indirectly assessed by the aortic isthmus systolic index (ISI) (nadir of incisura/peak systolic of the Doppler waveforms in the isthmus); the relation between ISI and QLUNGS was investigated. Fifty-one fetuses with TGA were compared with 74 normal controls matched for gestational age. TGA fetuses had higher QLV at T2 (58.6 ± 9.4% vs. 43.4 ± 5.0%, p < 0.001) and T3 (53.7 ± 8.9% vs. 43.9 ± 5.7%, p < 0.001). QLUNGS was higher in fetuses with TGA, in the second (50.4 ± 16.3% vs. 39.0 ± 16.8%, p = 0.007) and third trimesters of gestation (52.8 ± 22.0% vs. 37.1 ± 16.3%, p = 0.005). No difference was found between ISI values from normal and TGA groups. A significant inverse correlation was observed between ISI and QLUNGS (r = -0.55, p = 0.006). Central distribution of combined cardiac output of fetuses with simple TGA is characterized by a greater QLUNGS leading to a dominant LV. In prenatal TGA, changes in QLUNGS could be monitored by measuring ISI. The clinical importance of this last observation deserves further investigations.
OC18.04: Aortic isthmus predicts neonatal outcome in Twin-twin transfusion syndrome treated by laser coagulation
Ultrasound in Obstetrics & Gynecology, 2015
Retinopathy of prematurity
Ophthalmology Clinics of North America
The majority of cases of ROP regress spontaneously, but better treatment methods are needed to pr... more The majority of cases of ROP regress spontaneously, but better treatment methods are needed to prevent retinal detachment and other effects of ROP such as myopia. In the future, molecular mechanisms may be exploited to treat ROP.
Ultrasound in Obstetrics and Gynecology, 2010
Oral communication abstracts OC26.03: Table 1. Cardiac function parameters in study groups Contro... more Oral communication abstracts OC26.03: Table 1. Cardiac function parameters in study groups Control Ligature P DVPI 0.75 (0.25) 1.33 (0.75) 0.008 AoIPI 3.05 (0.45) 3.85 (1.16) 0.019 EF (%) 89.1 (8.2) 82 (24.6) n.s. IRT (ms) 38.1 (7.7) 50.1 (12.4) 0.004
Impressions of breastfeeding information and support among first-time mothers within a multiethnic community
The Canadian journal of nursing research = Revue canadienne de recherche en sciences infirmières, 2001
The purpose of this study was to document mothers' perceptions of breastfeeding information a... more The purpose of this study was to document mothers' perceptions of breastfeeding information and support received from hospital- and community-based health professionals within a multiethnic community. A telephone survey was conducted to assess: mothers' impressions of professional support for breastfeeding, whether recommended breastfeeding practices were followed by health professionals, and the nature and sources of breastfeeding information received. An ethnically diverse sample of 108 first-time breastfeeding mothers was surveyed at 3 weeks postpartum. Overall, the mothers' evaluations of professional support for breastfeeding were positive, even though they reported breastfeeding practices that fell short of recommended standards. Immigrant mothers were found more likely to experience hospital practices detrimental to breastfeeding success than Canadian-born mothers, but were also found more likely to receive professional breastfeeding support in the community. Sign...
Journal of the American Academy of Dermatology, 2014
Background: Visible vascular and pigmentary conditions have a negative impact on children's and a... more Background: Visible vascular and pigmentary conditions have a negative impact on children's and adolescents' quality of life (QoL). We sought to quantitate the effect of visible skin anomalies and their camouflage on QoL. Methods: In all, 41 patients, 5 years of age and older, were taught to use cosmetic camouflage. QoL was assessed using the Children's Dermatology Life Quality Index (CDLQI) before and 6 months after the intervention. Satisfaction and use were evaluated after 1 and 6 months. Results: Baseline QoL scores revealed a small impact of vascular anomalies (CDLQI score 4.2) and a small to moderate effect of pigmentary anomalies (CDLQI score 6.1). Six months after the intervention, QoL improved in the study population as a whole (CDLQI score 5.1 vs 2.1, P \ .001), with significant improvements documented for facial lesions and vascular malformations. Cosmetic camouflage was well tolerated and patients with pigmentary anomalies were more likely to continue using the products. Limitations: Limitations include small study population, few male patients, cultural influences not addressed, and limited range of conditions. Conclusions: Children and teenagers with visible vascular and pigmentary anomalies experience an impairment of QoL that is abrogated by introduction to use of cosmetic camouflage.
PLoS Genetics, 2011
In humans, chromosome-number abnormalities have been associated with altered recombination and in... more In humans, chromosome-number abnormalities have been associated with altered recombination and increased maternal age. Therefore, age-related effects on recombination are of major importance, especially in relation to the mechanisms involved in human trisomies. Here, we examine the relationship between maternal age and recombination rate in humans. We localized crossovers at high resolution by using over 600,000 markers genotyped in a panel of 69 French-Canadian pedigrees, revealing recombination events in 195 maternal meioses. Overall, we observed the general patterns of variation in fine-scale recombination rates previously reported in humans. However, we make the first observation of a significant decrease in recombination rates with advancing maternal age in humans, likely driven by chromosome-specific effects. The effect appears to be localized in the middle section of chromosomal arms and near subtelomeric regions. We postulate that, for some chromosomes, protection against non-disjunction provided by recombination becomes less efficient with advancing maternal age, which can be partly responsible for the higher rates of aneuploidy in older women. We propose a model that reconciles our findings with reported associations between maternal age and recombination in cases of trisomies.
Pediatric Research, 2003
The mucosal immune system is overactivated in Crohn disease (CD) and viral infections have been a... more The mucosal immune system is overactivated in Crohn disease (CD) and viral infections have been associated with clinical exacerbations. To investigate the potential association between mucosal inflammation and the cytokines involved in the early response to viruses, we analyzed colonic tissue levels of IL-2R␣, interferon-␣, and IL-15 in CD. Patients undergoing diagnostic colonoscopy were classified into controls (n ϭ 22) and three CD groups based on the histologic severity of inflammation and clinical activity: a) severely active CD (n ϭ 3); b) mild to moderately active CD (n ϭ 14); and c) quiescent CD (n ϭ 23). Rectal biopsies (two per patient) were homogenized and cytokine levels determined by ELISA kits. Statistical analysis was performed by ANOVA with Tukey and Scheffé tests. IL-2R␣ levels were increased in the active CD group compared with the quiescent CD group: a) 405 Ϯ 87, b) 159 Ϯ 31, and c) 33 Ϯ 15 pg/mg DNA (p Ͻ 0.001). The latter group was similar to controls (39 Ϯ 20 pg/mg DNA). Furthermore, a linear correlation (r ϭ 0.98) between IL-2R␣ and disease activity (Van Hees index) was observed. IL-15 levels were also higher in active compared with quiescent CD and controls: a) 0.69 Ϯ 0.23 and b) 0.72 Ϯ 0.31 versus c) 0.28 Ϯ 0.21 and 0.28 Ϯ 0.14 pg/mg DNA for controls (p Ͻ 0.05). Interferon-␣ levels were undetectable in all samples. Our data suggest that IL-2R␣ tissue levels correlate with CD activity. IL-15 is also overproduced in inflamed CD tissue. The lack of a parallel elevation of interferon-␣ does not support a role for viral induction of IL-15 in inflamed CD samples. (Pediatr Res 54: 456-461, 2003) Abbreviations CD, Crohn disease IL-2R␣, IL-2 receptor ␣-chain IBD, inflammatory bowel disease IFN-␣, interferon-␣
Pediatric Research, 2008
Children with hypoplastic left heart syndrome (HLHS) have an increased prevalence of central nerv... more Children with hypoplastic left heart syndrome (HLHS) have an increased prevalence of central nervous system (CNS) abnormalities. The extent to which this problem is due to CNS maldevelopment, prenatal ischemia, postnatal chronic cyanosis and/or multiple exposures to cardiopulmonary bypass is unknown. To better understand the etiology of CNS abnormalities in HLHS, we evaluated 68 neonates with HLHS; in 28 cases, both fetal ultrasound and echocardiogram data were available to assess head size, head growth and aortic valve anatomy (atresia or stenosis). In addition, we evaluated neuropathology in 11 electively aborted HLHS fetuses. The mean head circumference percentile in HLHS neonates was significantly smaller than HLHS fetuses (22 Ϯ 2% versus 40 Ϯ 4%, p Ͻ 0.001). A significant decrease in head growth, defined as a 50% reduction in head circumference percentile, was observed in half (14/28) of HLHS fetuses and nearly a quarter (6/28) were already growth restricted (Յ10%) at the time of initial evaluation. Brains from HLHS fetuses demonstrated chronic diffuse white matter injury of varying severity. These patterns of prenatal head growth and brain histopathology identify a spectrum of abnormal CNS development and/or injury in HLHS fetuses.
Pediatric Dermatology, 2009
Objectives: To explore the efficacy and safety of imiquimod 5% cream as a treatment for infantile... more Objectives: To explore the efficacy and safety of imiquimod 5% cream as a treatment for infantile hemangioma. Design: Phase II, openlabel, noncomparative study of imiquimod applied during 16 weeks, with posttherapy follow-up 16 weeks later (8 months total). Setting: Outpatient pediatric tertiary care referral center in Quebec, Canada. Participants: Healthy infants up to 8.8 months of age with previously untreated, nonulcerated, proliferative superficial or mixed infantile hemangioma, excluding periorbital, or perineal localization, ‡100 cm 2 in size. Intervention: Topical imiquimod applied three to seven times per week for 16 weeks to infantile hemangioma. Main Outcome Measures: Lesion area, volume, depth (Doppler ultrasound), and color (erythema), serum drug, and interferon-alpha levels. Results: Sixteen infants (11 girls, 5 boys) with a mean age at entry of 4.1 months and mean lesion area of 32.89 cm 2 , and volume of 39.98 cm 3 were enrolled. Two participants discontinued treatment early, one for an adverse event (crying upon application), the other because of the lack of compliance. Local skin reactions were consistent with those reported in adults. Two cases had a decrease and three had an increase in lesion parameters; otherwise no meaningful changes in lesion area, volume, or depth were observed. At the 4-month posttreatment visit, 11 of 14 subjects had improvement in erythema (marginal homogeneity test = 2.668, p = 0.008). Measured serum drug and interferon-alpha levels were low or undetectable. Conclusions: Treatment of infants with infantile hemangioma with imiquimod up to seven times per week for 16 weeks was generally well
Mapping of Familial Ventricular Septal Defects and Aneurysms to Chromosome 10
Heart, Lung and Circulation, 2009
Design and rationale of a genetic cohort study on congenital cardiac disease: experiences from a multi-institutional platform in Quebec
Cardiology in the Young, 2011
BackgroundCongenital cardiac disease is the most common malformation, and a substantial source of... more BackgroundCongenital cardiac disease is the most common malformation, and a substantial source of mortality and morbidity in children and young adults. A role for genetic factors is recognised for these malformations, but overall few predisposing loci have been identified. Here we report the rationale, design, and first results of a multi-institutional congenital cardiac disease cohort, assembled mainly from the French-Canadian population of the province of Quebec and centred on families with multiple affected members afflicted by cardiac malformations.MethodsFamilies were recruited into the study, phenotyped and sampled for DNA in cardiology clinics over the first 3 years of enrolment. We performed segregation analysis and linkage simulations in the subgroup of families with left ventricular outflow tract obstruction (LVOTO).ResultsA total of 1603 participants from 300 families were recruited, with 169 out of 300 (56.3%) families having more than one affected member. For the LVOTO ...
European Heart …, 2011
Methods and results A unique, large kindred segregating various forms of septal pathologiesinclu... more Methods and results A unique, large kindred segregating various forms of septal pathologiesincluding VSD, ventricular septal aneurysms, and atrial septal defects (ASD)was ascertained and characterized clinically and genetically. Eighteen family ...
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Papers by Roxanne Gendron