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NGS-based gene panel analysis in patients with obesity led to a definitive diagnosis of a genetic obesity disorder in 3.9% of obese probands, and a possible diagnosis in an additional 5.4% of obese probands. The highest yield was achieved in a selected paediatric subgroup, establishing a definitive diagnosis in 12 out of 164 children with severe early onset obesity (7.3%). These findings give a realistic insight in the diagnostic yield of genetic testing for patients with obesity and could help these patients to receive (future) personalised treatment.

Objective Leptin receptor (LepR) deficiency is an autosomal-recessive endocrine disorder causing early-onset severe obesity, hyperphagia and pituitary hormone deficiencies. As effective pharmacological treatment has recently been developed, diagnosing LepR deficiency is urgent. However, recognition is challenging and prevalence is unknown. We aim to elucidate the clinical spectrum and to estimate the prevalence of LepR deficiency in Europe. Design Comprehensive epidemiologic analysis and systematic literature review. Methods We curated a list of LEPR variants described in patients and elaborately evaluated their phenotypes. Subsequently, we extracted allele frequencies from the Genome Aggregation Database (gnomAD), consisting of sequencing data of 77 165 European individuals. We then calculated the number of individuals with biallelic disease-causing LEPR variants. Results Worldwide, 86 patients with LepR deficiency are published. We add two new patients, bringing the total of published patients to 88, of which 21 are European. All patients had early-onset obesity; 96% had hyperphagia; 34% had one or more pituitary hormone deficiencies. Our calculation results in 998 predicted patients in Europe, corresponding to a prevalence of 1.34 per 1 million people (95% CI: 0.95–1.72). Conclusions This study shows that LepR deficiency is more prevalent in Europe (n = 998 predicted patients) than currently known (n = 21 patients), suggesting that LepR deficiency is underdiagnosed. An important cause for this could be lack of access to genetic testing. Another possible explanation is insufficient recognition, as only one-third of patients has pituitary hormone deficiencies. With novel highly effective treatment emerging, diagnosing LepR deficiency is more important than ever.

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Background Underlying medical causes of obesity (endocrine disorders, genetic obesity disorders, cerebral or medication-induced obesities) are thought to be rare. Even in specialized pediatric endocrinology clinics, low diagnostic yield is reported, but evidence is limited. Identifying these causes is vital for patient-tailored treatment. Objectives To present the results of a systematic diagnostic workup in children and adolescents referred to a specialized pediatric obesity center. Methods This is a prospective observational study. Prevalence of underlying medical causes was determined after a multidisciplinary, systematic diagnostic workup including growth charts analysis, extensive biochemical and hormonal assessment and genetic testing in all patients.

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Chromosomal microarray analysis is an important diagnostic tool to identify copy number variations (CNV). Some of the CNVs affect susceptibility regions, which means that deletions or duplications in these regions have partial penetrance and often give an increased risk for a spectrum of neurocognitive disorders. Not much is known about the impact of rare CNV susceptibility syndromes on the life of patients or their parents. In this study, we focus on one specific susceptibility CNV disorder, 16p11.2 deletion syndrome. This rare condition is characterised by an increased risk of mild intellectual disability, autism spectrum disorder, epilepsy, and obesity. We aimed to explore the impact of such a disorder on the family members involved in the daily care of children with this syndrome. Three focus group discussions were held with 23 Dutch (grand)parents. Thematic analysis was performed by two independent researchers. The following five themes emerged: (1) the end of a diagnostic odyssey and response to the diagnosis, (2) after the diagnosis—life with a child with 16p11.2 deletion syndrome, (3) access to medical care and support services, (4) nobody knows what 16p11.2 deletion syndrome is, and (5) future perspective—ideal care. The participants experienced a lack of knowledge among involved professionals. Together with the large variability of the syndrome, this led to fragmented care and unfulfilled needs regarding healthcare, social, and/or educational assistance. Care for children with a CNV susceptibility syndrome could be improved by a multidisciplinary approach or central healthcare professional, providing education and information for all involved professionals.