👤 Agnès Linglart

Pathogenic variants in five established leptin-melanocortin pathway genes (LEP, LEPR, MC4R, PCSK1, POMC) are associated with severe early-onset obesity and are targets for emerging treatments. However, these variants are rare in these patients, suggesting the involvement of additional genes interacting with this pathway. Next-generation sequencing (NGS) analysis was performed in 395 patients with severe obesity, including 213 children (mean BMI: 56.3 kg/m Pathogenic heterozygous variants were identified in 34 patients (8.6%), 18 of them harboring pathogenic variants in the 15 additional genes. In adults, early-onset obesity was more frequent in potentially pathogenic variants carriers than in non-carriers (83.3% vs. 55.0%, p = 0.04). No differences were observed in the other phenotypic characteristics. This supports the relevance of expanded genetic testing in severe obesity. Early-onset obesity remains a key clinical feature to guide genetic investigation and identify patients who may benefit from early personalized care and targeted treatments. Show less

15q24 microdeletion and microduplication syndromes are genetic disorders caused by non-allelic homologous recombination between low-copy repeats (LCRs) in the 15q24 chromosome region. Individuals with 15q24 microdeletion and microduplication syndromes share a common 1.2 Mb critical interval, spanning from LCR15q24B to LCR15q24C. Patients with 15q24 microdeletion syndrome exhibit distinct dysmorphic features, microcephaly, variable developmental delay, multiples congenital anomalies while individuals with reciprocal 15q24 microduplication syndrome show mild developmental delay, facial dysmorphism associated with skeletal and genital abnormalities. We report the first case of a 10 year-old girl presenting mild developmental delay, psychomotor retardation, epilepsy, ventricular arrhythmia, overweight and idiopathic central precocious puberty. 180K array-CGH analysis identified a 1.38 Mb heterozygous interstitial 15q24.1 BP4-BP1 microdeletion including HCN4 combined with a concomitant 2.6 Mb heterozygous distal 15q24.2q24.3 microduplication. FISH analysis showed that both deletion and duplication occurred de novo in the proband. Of note, both copy number imbalances did not involve the 1.2 Mb minimal deletion/duplication critical interval of the 15q24.1q24.2 chromosome region (74.3-75.5 Mb). Sequencing of candidate genes for epilepsy and obesity showed that the proband was hemizygous for paternal A-at risk allele of BBS4 rs7178130 and NPTN rs7171755 predisposing to obesity, epilepsy and intellectual deficits. Our study highlights the complex interaction of functional polymorphisms and/or genetic variants leading to variable clinical manifestations in patients with submicroscopic chromosomal aberrations. Show less