👤 Mathieu Peyre

The potential causal effects of perinatal exposure to polyunsaturated fatty acids (PUFAs) on child neurodevelopment remains controversial. To infer causation, we assessed the association of perinatal PUFA patterns and child neurodevelopment by using conventional regression analyses and 1-sample Mendelian randomization (MR). Among 1096 mother-child pairs from the French Etude des Déterminants Pré- et Postnatals du Développement de la Santé de L'enfant cohort, patterns of perinatal exposure to PUFAs were previously identified combining PUFA levels from maternal and cord erythrocytes, and colostrum. Child verbal, performance, and full-scale intelligence quotients (IQs) were assessed at ages 5-6 y. Among maternal fatty acid desaturase (FADS) variants genotyped, 2 candidates, rs174546 (FADS1) and rs174634 (FADS3), were selected, as instrumental variables, for the MR analysis. The association of PUFA patterns with child IQ was examined by conventional multivariable linear regression and 2-stage least-squares MR regression. In the conventional approach, the first pattern "high omega-3 long-chain PUFAs (LC-PUFAs), low omega-6 LC-PUFAs" was positively associated with verbal IQ [β (95% confidence interval) = 1.24 (0.27, 2.21) points per 1 standard deviation (SD) increase in pattern] and full-scale IQ [1.11 (0.18, 2.05)]. This pattern was independent of FADS variants, rendering MR analysis inapplicable. The third pattern, "colostrum LC-PUFAs," was positively associated with verbal [1.11 (0.19, 2.02)], performance [1.01 (0.09, 1.93)], and full-scale IQ [1.13 (0.25, 2.01)]. The MR approach, based on genetic instruments strongly associated with the third pattern, supported the beneficial effect on performance IQ [2.93 (0.05, 5.81) points per 1 SD increase in genetically predicted pattern]. The MR also suggested a deleterious effect of the fourth pattern "linoleic acid (LA) and dihomo-gamma-linolenic acid (DGLA)" on performance IQ [-1.66 (-3.22, -0.09)]. These findings supported the potential beneficial effects of perinatal exposure to LC-PUFAs on child neurodevelopment while highlighting possible adverse effects associated with exposure to LA and DGLA. Show less

The molecular pathogenesis of pediatric ependymoma remains unclear. Our study was designed to identify genetic changes implicated in ependymoma progression. We characterized 59 ependymoma samples (33 at diagnosis and 26 at relapse) using array-comparative genomic hybridization (aCGH). Specific chromosomal imbalances were confirmed by fluorescent in situ hybridization, and candidate genes were assessed by real-time quantitative polymerase chain reaction (qPCR), immunohistochemistry, sequencing, and in vitro functional studies. aCGH analysis revealed a significant increase in genomic imbalances on relapse compared with diagnosis, such as gain of 9qter and 1q (54% v 21% and 12% v 0%, respectively) and loss of 6q (27% v 6%). Supervised tumor classification showed that gain of 9qter was associated with tumor recurrence, age older than 3 years, and posterior fossa location. Using a candidate-gene strategy, we found an overexpression of two potential oncogenes at the locus 9qter: Tenascin-C and Notch1. Moreover, Notch pathway analysis (qPCR) revealed overexpression of Notch ligands, receptors, and target genes (Hes-1, Hey2, and c-Myc), and downregulation of Notch repressor Fbxw7. We confirmed by immunohistochemistry the overexpression of Tenascin-C and Hes-1. We detected Notch1 missense mutations in 8.3% of the tumors (only in the posterior fossa location and in case of 9q33-34 gain). Furthermore, inhibition of Notch pathway with a gamma-secretase inhibitor impaired the growth of ependymoma stem cell cultures. The activation of the Notch pathway and Tenascin-C seem to be important events in ependymoma progression and may represent future targets for therapy. We report, to our knowledge for the first time, recurrent oncogenic mutations in pediatric posterior fossa ependymomas. Show less