Biomedical subjects

Hilde Peeters

Publications and source records attributed to Hilde Peeters.

7 recordsLinked to original sources

PubMed2026

Shared genetic basis and structure of syndromic and normal facial variation.

The question of how gene mutations of large effect and common variants of small effect relate to phenotypic variation dates from the origins of genetics. Mendelian diseases result from rare germline variants with major effects, while complex traits are associated with multiple, mostly common variants of small effect. High-dimensional phenotypes, such as facial shape, can shed new light on this age-old dichotomy, as their variation can be characterized in terms of directions in multivariate morphospace. Within such spaces, do Mendelian disease mutations move phenotypes along the same directions as common variants, or do they forge new directions that diverge from the common structure of background variation? Here, we analyze facial shape variation for 66 syndromes, quantify multivariate axes of facial shape variation for each syndrome, and test whether common genetic variants in cohorts of non-syndromic subjects are associated with phenotypic position along these same axes. We find that syndromic facial shape generally follows the background variance-covariance structure of facial shape in the general population. Furthermore, syndromic probands' unaffected relatives have subtle facial morphology resembling the syndromes of their affected relatives. These results suggest that Mendelian disease variants act on facial shape in ways similar to common variants. Syndromic probands with higher "severity" likely occur on genetic backgrounds with higher cumulative severity of common variants for each syndromic axis. These findings position Mendelian diseases at extremes along phenotypic continua that exist in the background population rather than as qualitatively different phenotypes distinct from the overall structure of normal human phenotypic variation.

Humans↗

PubMed2026

Evidence supporting the role of GIGYF2 in synapse development and autism.

Autism spectrum disorder (ASD) is a heterogeneous condition in which genetically defined subtypes offered insights into underlying biological mechanisms and potential targeted treatments. Here, we investigate the clinical and pathogenic significance of GIGYF2 variants in ASD through an integrated approach combining clinical genetics, conditional knockout (cKO) mouse models, neurobiology, and molecular studies. Through targeted sequencing, large-scale genomic data analysis of neurodevelopmental disorder cohorts, and international collaborations, we identified ten affected individuals from eight families harboring de novo or dominantly inherited likely gene-disruptive (LGD) variants and 13 affected individuals from 13 families with de novo missense variants in GIGYF2. Clinical characterization of 16 probands with GIGYF2 variants revealed common features, including ASD, language problems, intellectual disability, and anxiety. In a Gigyf2 cKO mouse model, we observed pronounced autistic-like behaviors, cognitive deficits, and anxiety-like behaviors, mirroring phenotypes observed in affected individuals. Mechanistically, Gigyf2 deficiency disrupted synaptic homeostasis, as evidenced by altered spine density and miniature excitatory postsynaptic currents, and impaired IGF-1R/mTOR signaling, along with dysregulation of synapse-related genes such as Nrp2. Pharmacological inhibition of mTOR with rapamycin or Torin1, as well as Nrp2 knockdown rescued synaptic defects in Gigyf2 KO neurons. These findings define a novel ASD subtype associated with GIGYF2 variants and establish GIGYF2 as a key regulator of synaptic development and function, implicating GIGYF2 dysfunction in ASD pathogenesis and highlighting the IGF-1R/mTOR pathway as a potential therapeutic target for GIGYF2-related ASD subtype.

Journal Article↗

PubMed2025

Optimized phenotyping of complex morphological traits: enhancing discovery of common and rare genetic variants.

Genotype-phenotype (G-P) analyses for complex morphological traits typically utilize simple, predetermined anatomical measures or features derived via unsupervised dimension reduction techniques (e.g. principal component analysis (PCA) or eigen-shapes). Despite the popularity of these approaches, they do not necessarily reveal axes of phenotypic variation that are genetically relevant. Therefore, we introduce a framework to optimize phenotyping for G-P analyses, such as genome-wide association studies (GWAS) of common variants or rare variant association studies (RVAS) of rare variants. Our strategy is two-fold: (i) we construct a multidimensional feature space spanning a wide range of phenotypic variation, and (ii) within this feature space, we use an optimization algorithm to search for directions or feature combinations that are genetically enriched. To test our approach, we examine human facial shape in the context of GWAS and RVAS. In GWAS, we optimize for phenotypes exhibiting high heritability, estimated from either family data or genomic relatedness measured in unrelated individuals. In RVAS, we optimize for the skewness of phenotype distributions, aiming to detect commingled distributions that suggest single or few genomic loci with major effects. We compare our approach with eigen-shapes as baseline in GWAS involving 8246 individuals of European ancestry and in gene-based tests of rare variants with a subset of 1906 individuals. After applying linkage disequilibrium score regression to our GWAS results, heritability-enriched phenotypes yielded the highest SNP heritability, followed by eigen-shapes, while commingling-based traits displayed the lowest SNP heritability. Heritability-enriched phenotypes also exhibited higher discovery rates, identifying the same number of independent genomic loci as eigen-shapes with a smaller effective number of traits. For RVAS, commingling-based traits resulted in more genes passing the exome-wide significance threshold than eigen-shapes, while heritability-enriched phenotypes lead to only a few associations. Overall, our results demonstrate that optimized phenotyping allows for the extraction of genetically relevant traits that can specifically enhance discovery efforts of common and rare variants, as evidenced by their increased power in facial GWAS and RVAS.

Humans↗

PubMed2006

Sesn1 is a novel gene for left-right asymmetry and mediating nodal signaling.

Remarkable progress has been made in understanding the molecular mechanisms underlying left-right asymmetry in vertebrate animal models but little is known on left-right axis formation in humans. Previously, we identified SESN1 (also known as PA26) as a candidate gene for heterotaxia by positional cloning of the breakpoint regions of a de novo translocation in a heterotaxia patient. In this study, we show by means of a zebrafish sesn1-knockdown model that Sesn1 is required for normal embryonic left-right determination. In this model, developmental defects and expression data of genes implicated in vertebrate left-right asymmetry indicate a role for Sesn1 in mediating Nodal signaling. In the lateral plate mesoderm, Nodal signaling plays a central role in left-right axis formation in vertebrates and is mediated by FoxH1 transcriptional induction. In line with this, we show that Sesn1 physically interacts with FoxH1 or a FoxH1-containing complex. Mutation analysis in a panel of 234 patients with isolated heterotaxia did not reveal mutations, indicating that these are only exceptional causes of human heterotaxia. In this study, we identify SESN1 as an indispensable gene for vertebrate left-right asymmetry and a new player in mediating Nodal signaling.

Animals↗

PubMed2006

Human laterality disorders.

Heterotaxia is a group of congenital disorders characterized by a misplacement of one or more organs according to the left-right axis. Bilateral asymmetry of internal organs is conserved among all vertebrate species. Analyses in animal models such as mouse, chicken, frog and zebrafish allowed for a remarkable progress of knowledge on the embryonic and genetic mechanisms underlying internal left-right asymmetry. In this review we focus on the insights from these model organisms that are useful for a better understanding of the etiology and pathogenesis of human heterotaxia. The known causes of human heterotaxia are reviewed and situated within the conceptual framework that originates from vertebrate model organisms. Furthermore, we attempt to apply the rapidly increasing insights gained from both animal models and human genetics to clinical practice in order to contribute to a more accurate conceptual classification, genetic diagnosis and counseling.

Animals↗

PubMed2006

Two female siblings with congenital heart disease, postaxial polydactyly, ectopic neuropituitary gland, hair anomalies and characteristic facial features: a new syndrome?

We present two siblings from unrelated parents presenting with intrauterine growth retardation, a congenital heart defect, postaxial polydactyly, a brain malformation (ectopic neuropituitary gland associated with a hypoplastic adenopituitary in one of them, and a hypoplastic cerebellum and vermis in the other), abnormal hair with temporal balding, a striking facial dysmorphism and, at least in the child who survived, postnatal growth retardation and severe developmental delay. This probably represents a novel syndrome.

Choristoma↗

PubMed2005

Focal preauricular dermal dysplasia: distinctive congenital lesions with a bilateral and symmetric distribution.

We present three unrelated children with distinctive congenital facial skin lesions. All three children had two to three well-circumscribed, round or oval vesicular lesions, 1/2-1 cm in diameter on each cheek at birth. The lesions were located along an arc from the top of the ear to the corner of the mouth. Patient 1 was born with a unilateral cleft lip and palate, and a cutaneous hemangioma in the right palm. She is developing normally. Patient 2 has neurological sequelae after suffering an unexplained large left-sided intracerebral hemorrhage perinatally. Patient 3 has a small chin, somewhat cupped ears and a nevus on the left foot. He is developing normally. This condition has been described in the dermatological literature as focal facial dermal hypoplasia with preauricular localization. No cases with associated anomalies have been published previously. Most cases have been sporadic but familial occurrence compatible with autosomal dominant and autosomal recessive inheritance has been documented. If an embryonic fusion defect of the mandibular and maxillary prominences underlies the anomaly, the cleft lip and palate seen in one of our patients may be non-coincidental. No mutations in the TWIST2 gene were found in DNA extracted from peripheral leukocytes in the two children who were investigated.

DNA Mutational Analysis↗