Intrauterine exposures mediated by maternal diet may affect risk of cardiovascular disease, obesity, and type 2 diabetes. Recent evidence, primarily from animal studies and observational data in humans, suggests that the epigenome can be altered by maternal diet during the periconceptional period and that these programming events may underlie later disease risk. A randomized controlled trial of periconceptional micronutrient supplementation in The Gambia, where seasonal nutritional variations affect fetal growth and postnatal outcomes, provided a unique opportunity to test this hypothesis. Specifically, we targeted imprinted genes, which play important roles in allocation of maternal resources while being epigenetically regulated. DNA methylation at 12 differentially methylated regions (DMRs) was analyzed in cord blood samples from 58 offspring of women participating in a double-blind randomized-controlled trial of pre- and periconceptional micronutrient supplementation (including folate, zinc, and vitamins A, B, C, and D). We observed sex-specific effects of micronutrient supplementation, reducing methylation levels at two of the DMRs analyzed, IGF2R in girls and GTL2-2 in boys. This pilot study is the first to analyze DNA methylation in the context of a randomized controlled trial, and it provides suggestive evidence that periconceptional maternal nutrition alters offspring methylation at imprinted loci.

Phelan-McDermid syndrome (PMS, OMIM# 606232) results from either different rearrangements at the distal region of the long arm of chromosome 22 (22q13.3) or pathogenic sequence variants in the SHANK3 gene. SHANK3 codes for a structural protein that plays a central role in the formation of the postsynaptic terminals and the maintenance of synaptic structures. Clinically, patients with PMS often present with global developmental delay, absent or severely delayed speech, neonatal hypotonia, minor dysmorphic features, and autism spectrum disorders (ASD), among other findings. Here, we describe a cohort of 210 patients with genetically confirmed PMS. We observed multiple variant types, including a significant number of small deletions (<0.5 Mb, 64/189) and SHANK3 sequence variants (21 cases). We also detected multiple types of rearrangements among microdeletion cases, including a significant number with post-zygotic mosaicism (9.0%, 17/189), ring chromosome 22 (10.6%, 20/189), unbalanced translocations (de novo or inherited, 6.4%), and additional rearrangements at 22q13 (6.3%, 12/189) as well as other copy number variations in other chromosomes, unrelated to 22q deletions (14.8%, 28/189). We compared the clinical and genetic characteristics among patients with different sizes of deletions and with SHANK3 variants. Our findings suggest that SHANK3 plays an important role in this syndrome but is probably not uniquely responsible for all the spectrum features in PMS. We emphasize that only an adequate combination of different molecular and cytogenetic approaches allows an accurate genetic diagnosis in PMS patients. Thus, a diagnostic algorithm is proposed.

BackgroundRubinstein-Taybi syndrome (RSTS) is a rare autosomal dominant neurodevelopmental disorder characterized by broad thumbs and halluces. RSTS is caused by mutations in CREBBP and in EP300 genes in 50–60% and 8%, respectively. Up to now, 76 RSTS-EP300 patients have been described. We present the clinical and molecular characterization of a cohort of RSTS patients carrying EP300 mutations.MethodsPatients were selected from a cohort of 72 individuals suspected of RSTS after being negative in CREBBP study. MLPA and panel-based NGS EP300 were performed.ResultsEight patients were found to carry EP300 mutations. Phenotypic characteristics included: intellectual disability (generally mild), postnatal growth retardation, infant feeding problems, psychomotor and language delay and typical facial dysmorphisms (microcephaly, downslanting palpebral fissures, columella below the alae nasi, and prominent nose). Broad thumbs and/or halluces were common, but angulated thumbs were only found in two patients. We identified across the gene novel mutations, including large deletion, frameshift mutations, nonsense, missense and splicing alterations, confirming de novo origin in all but one (the mother, possibly underdiagnosed, has short and broad thumbs and had learning difficulties).ConclusionsThe clinical evaluation of our patients corroborates that clinical features in EP300 are less marked than in CREBBP patients although it is difficult to establish a genotype-phenotype correlation although. It is remarkable that these findings are observed in a RSTS-diagnosed cohort; some patients harbouring EP300 mutations could present a different phenotype. Broadening the knowledge about EP300-RSTS phenotype may contribute to improve the management of patients and the counselling to the families.

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Abstract Background: Rubinstein-Taybi syndrome (RSTS) is a rare congenital disorder characterized by broad thumbs and halluces, intellectual disability, distinctive facial features, and growth retardation. Clinical manifestations of RSTS are varied and overlap with other syndromes' phenotype, which makes clinical diagnosis challenging. CREBBP is the major causative gene (55%-60% of the cases), whereas pathogenic variants found in EP300 represent the molecular cause in 8% of RSTS patients. A wide range of CREBBP pathogenic variants have been reported so far, including point mutations (30%-50%) and large deletions (10%). Methods: The aim of this study was to characterize the CREBBP genetic variant spectrum in 39 RSTS patients using Multiplex Ligation-dependent Probe Amplification and DNA sequencing techniques (Sanger and Trio-based whole-exome sequencing). Results: We identified 15 intragenic deletions/duplications, ranging from one exon to the entire gene. As a whole, 25 de novo point variants were detected: 4 missense, 12 nonsense, 5 frameshift, and 4 splicing pathogenic variants. Three of them were classified as of uncertain significance and one of the patients carried two different variants. Conclusion: Seventeen of the 40 genetic variants detected were reported for the first time in this work contributing, thus, to expand the molecular knowledge of this complex disorder. K E Y W O R D S CREBBP, epigenetics, genotype-phenotype correlation, Rubinstein-Taybi syndrome 2 of 13 | PÉREZ-GRIJALBA Et AL.

BackgroundRubinstein-Taybi syndrome (RSTS; OMIM #180849, #613684) is a rare autosomal dominant genetic condition characterized by broad thumbs and halluces, facial dysmorphism, short stature and variable degree of intellectual disability. RSTS is associated with mutations in CREBBP and EP300 genes in 50–60% and 5–8% of cases, respectively. The majority of cases are de novo heterozygous mutations.Case presentationHere we describe a familial RSTS case, associated with a novel EP300 mutation. The proband was a 9 years old female, with mild learning difficulties. Her mother, who also had learning difficulties, was found to have short and broad thumbs. MLPA and panel-based NGS of CREBBP and EP300 were performed. A novel heterozygous frameshift mutation in exon 31 of the EP300 gene (c.7222_7223del; p.(Gln2408Glufs*39)) was found in both.ConclusionsThis case represents the first case of inherited EP300-RSTS. The location of the frameshift deletion not affecting HAT domain and PHD finger, could explain the mild phenotype and the well-preserved intelligence. These patients are mildly affected, and this case highlights the possible missed diagnosis. We would recommend molecular testing of apparently healthy parents, and in the case of inherited mutations, of all adult first degree relatives at risk.Electronic supplementary materialThe online version of this article (doi:10.1186/s12881-016-0361-8) contains supplementary material, which is available to authorized users.