Genetic forms of obesity, including monogenic (MO) and syndromic (SO) obesity, are characterised by severe, early-onset weight gain due to disrupted central regulation of body weight, typically involving key pathways such as the leptin-melanocortin axis. These alterations result in marked hyperphagia and complex eating behaviours, yet clinical characterisation remains limited. This review aimed to describe the multidimensional eating behaviour profiles across genetically confirmed obesity, explore their variability, and evaluate existing assessment tools to support early diagnosis, personalised care, and therapeutic monitoring. We conducted a systematic review following PRISMA guidelines including publications up to 4 September 2025. A total of 162 studies involving individuals with genetically confirmed SO or MO were analysed. Eating behaviours were categorised into nine dimensions: food-centred thinking, food-seeking/stealing, hunger/satiety, ingestive/oral behaviours, nutritional quality, food preferences, food acceptability, loss of control eating, and eating restraint. Assessment tools and methodologies were systematically reviewed. Hyperphagia was consistently reported across genetic aetiologies, though definitions and measures remain heterogeneous. Prader-Willi syndrome (PWS), the most studied condition, was associated with early-onset hyperphagia, increased hunger, pronounced food preoccupation, compulsive food-seeking/stealing and strong preferences for carbohydrate-rich, large quantities and unusual food items. Similar behavioural traits were found in other SO and MO, including Bardet-Biedl syndrome, Alström syndrome, Fragile X syndrome, WAGR syndrome, pseudohypoparathyroidism Ia, 16p11.2 deletion and LEPR, POMC, and MC4R deficiencies. Behavioural traits appeared relatively consistent across sex, age, and genotypes within syndromes. Most studies relied on caregiver reports; existing tools such as the Hyperphagia Questionnaire (HQ) and Food-Related Problem Questionnaire (FRPQ), developed primarily for PWS, did not fully capture the behavioural spectrum or suit all cognitive profiles. Tools applicable to individuals without intellectual developmental disorders, particularly adults living independently, remain scarce. This is the first systematic review to comprehensively map eating behaviours across rare genetic obesity using a multidimensional approach. It highlights the shared feature of disrupted appetite regulation and emphasises the need for standardised, multidimensional tools suitable for both clinical and research contexts. Better behavioural characterisation will support targeted therapies and improve outcome monitoring in these high-need populations.

WT1-related disorders comprise a spectrum of conditions resulting from mutations or deletions of the WT1 gene. Alteration in this gene have been associated with many syndromes, including WAGR syndrome, Denys-Drash syndrome (DDS), Frasier syndrome (FS) and Meacham syndrome. We present the case of an 8-year-old phenotypically female child with symptoms of end-stage kidney disease (ESKD), hypertension and anasarca, requiring renal replacement therapy. This case is distinctive due to its unusual onset, the presence of thrombotic microangiopathy (TMA), and the detection of a heterozygous missense mutation in the WT1 gene (c.1298G>A, p.Cys433Tyr) located in exon 8, in association with a 46 XY karyotype. The kidney biopsy indicated advanced focal segmental glomerulosclerosis (FSGS) with characteristics of TMA, implying a possible alternative diagnosis. In light of the heightened malignancy risk, the patient had preventative laparoscopic gonadectomy, which revealed rudimentary testicular tissues. The identified genotype points toward a diagnosis of DDS. However, the clinical presentation is more consistent with features typically seen in FS. This discrepancy highlights the significant phenotypic and genotypic overlap between the two syndromes. As a result, there is ongoing discussion in the literature about whether DDS and FS should be considered distinct clinical entities or rather variable expressions along a shared disease spectrum.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized primarily by social deficits and repetitive behaviors. The mechanisms of ASD are complex and are not yet fully understood, although many ASD risk genes and mouse models have been reported. It has been suggested that deletion of PRRG4 (proline-rich and Gla domain 4) deletion may contribute to autism symptoms in patients with WAGR (Wilms' tumor, aniridia, gonadoblastoma, mental retardation) syndrome. The mouse model with PRRG4 gene deletion has not been reported so far. This study investigated whether brain-specific conditional knockout of PRRG4 induces ASD-like symptoms in mice by crossing the PRRG4fl/fl mice with Emx1-Cre mice, which express Cre in the cerebral cortex and hippocampus. The PRRG4 brain-specific knockout (PRRG4fl/fl-Cre+, PRRG4-CKO) mice exhibited social deficits, repetitive behaviors, and anxiety-like symptoms compared to PRRG4fl/fl control mice according to the results of various behavioral tests. PRRG4 knockout led to the increase in total dendritic length, branching, and dendritic spine density in the pyramidal neurons of the cerebral cortex and hippocampus, as well as enhanced levels of synaptic proteins including SYP and PSD95. Immunoprecipitation experiment with PRRG4 antibodies showed dramatic decreased interaction of PRRG4 and MAGI2 proteins in brain tissues from PRRG4-CKO mice compared to PRRG4fl/fl control mice. GST-RBD pull-down assay showed a significant decrease in RhoA-GTP levels in the cerebral cortex and hippocampus of PRRG4-CKO mice. Brain-specific conditional knockout of the PRRG4 in mice leads to ASD-like symptoms. PRRG4 protein may regulate dendritic and synaptic development in mice by activating RhoA through interaction with MAGI2. These findings provide evidence for a comprehensive understanding of PRRG4 function in vivo and support the association between PRRG4 loss and ASD phenotypes observed in WAGR syndrome.

Congenital aniridia (CA) is a severe and complex disorder involving the entire eye, primarily characterized by iris anomalies alongside other clinical features that pose significant risks to vision. This study seeks to offer a comprehensive overview of CA by detailing its clinical presentations, genetic underpinnings, associated phenotypes, and differential diagnoses. Additionally, it proposes a diagnostic framework to distinguish CA from other conditions that present with similar iris abnormalities. We conducted a comprehensive literature review to compile and analyze clinical and genetic data related to CA and its differential diagnoses. We included all studies describing the clinical characteristics, pathogenic variants, and associated syndromes of congenital aniridia. CA presents a wide range of ocular symptoms. Pathogenic variants in the PAX6 gene are the primary genetic cause of CA, though variations in other genes, including FOXC1, PITX2, CYP1B1, FOXD3, PITX3, CPAMD8, ITPR1, TENM3, TRIM44, COL4A1, CRYAA, and PXDN may also be implicated. The differential diagnosis of CA requires careful consideration of conditions with overlapping symptoms, such as WAGR syndrome (which involves deletions affecting the PAX6 and WT1 genes on chromosome 11p13, and potentially BDNF on 11p14.1), Axenfeld-Rieger syndrome (FOXC1/PITX2), ring-chromosome 6 syndrome (which involves FOXC1 microdeletion), COL4A1-related anterior segment dysgenesis, Gillespie syndrome (ITPR1 gene) or Peters anomaly. Accurate diagnosis can be achieved by evaluating specific clinical features-including iris anomalies, aniridia-associated keratopathy, cataracts, glaucoma, foveal hypoplasia, nystagmus, and optic nerve head abnormalities-supplemented by genetic testing. Understanding the diverse clinical presentations and genetic basis of diseases associated with iris abnormalities is essential for accurate diagnosis and effective management. Integrating genetic diagnostics into the evaluation process enables the development of tailored treatment strategies, which can significantly improve patient outcomes.