Genetic obesity: next-generation sequencing results of 1230 patients with obesity.

BACKGROUND: Obesity is a global and severe health problem. Due to genetic heterogeneity, the identification of genetic defects in patients with obesity can be time consuming and costly. Therefore, we developed a custom diagnostic targeted next-generation sequencing (NGS)-based analysis to simultaneously identify mutations in 52 obesity-related genes. The aim of this study was to assess the diagnostic yield of this approach in patients with suspected genetic obesity. METHODS: DNA of 1230 patients with obesity (median BMI adults 43.6 kg/m2; median body mass index-SD children +3.4 SD) was analysed in the genome diagnostics section of the Department of Genetics of the UMC Utrecht (The Netherlands) by targeted analysis of 52 obesity-related genes. RESULTS: In 48 patients pathogenic mutations confirming the clinical diagnosis were detected. The majority of these were observed in the MC4R gene (18/48). In an additional 67 patients a probable pathogenic mutation was identified, necessitating further analysis to confirm the clinical relevance. CONCLUSIONS: 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.

Long-Term Weight Outcome After Bariatric Surgery in Patients with Melanocortin-4 Receptor Gene Variants: a Case-Control Study of 105 Patients.

INTRODUCTION: Pathogenic heterozygous MC4R variants are associated with hyperphagia and variable degrees of obesity. Several research groups have reported short-term weight loss outcomes after bariatric surgery in a few patients with MC4R variants, but lack of longer-term data prevents evidence-based clinical decision-making. MATERIALS AND METHODS: Bariatric surgery patients with heterozygous (likely) pathogenic MC4R variants, from three collaborating centers in the Netherlands, France, and the UK, were compared to matched controls (matched 2:1 for age, sex, preoperative BMI, surgical procedure, and diabetes mellitus, but without MC4R mutations). Weight loss and regain outcomes up to 6 years of follow-up were compared. RESULTS: At 60 months of follow-up after RYGB, cases with MC4R variants showed weight regain with a mean of 12.8% (± 10.4 SD) total weight loss (TWL) from nadir, compared to 7.9% (± 10.5 SD) in the controls (p = 0.062). Among patients receiving SG, the cases with MC4R variants experienced inferior weight loss (22.6% TWL) during the first year of follow-up compared to the controls (29.9% TWL) (p = 0.010). CONCLUSIONS: This multicenter study reveals inferior mid-term weight outcomes of cases with MC4R variants after SG, compared to RYGB. Since adequate weight loss outcomes were observed after RYGB, this procedure would appear to be an appropriate surgical approach for this group. However, the pattern of weight regain seen in cases with MC4R variants after both RYGB and SG highlights the need for pro-active lifelong management to prevent relapse, as well as careful expectation management.

Recontacting in light of new genetic diagnostic techniques for patients with intellectual disability: Feasibility and parental perspectives.

A higher diagnostic yield from new diagnostic techniques makes re-evaluation in patients with intellectual disability without a causal diagnosis valuable, and is currently only performed after new referral. Active recontacting might serve a larger group of patients. We aimed to evaluate parental perspectives regarding recontacting and its feasibility in clinical genetic practice. A recontacting pilot was performed in two cohorts of children with intellectual disability. In cohort A, parents were recontacted by phone and in cohort B by letter, to invite them for a re-evaluation due to the new technologies (array CGH and exome sequencing, respectively). Parental opinions, preferences and experiences with recontacting were assessed by a self-administered questionnaire, and the feasibility of this pilot was evaluated. 47 of 114 questionnaires were returned. In total, 87% of the parents believed that all parents should be recontacted in light of new insights, 17% experienced an (positive or negative) emotional reaction. In cohort A, approached by phone, 36% made a new appointment for re-evaluation, and in cohort B, approached by letter, 4% did. Most parents have positive opinions on recontacting. Recontacting might evoke emotional responses that may need attention. Recontacting is feasible but time-consuming and a large additional responsibility for clinical geneticists.

Outcome of surveillance and prophylactic salpingo-oophorectomy in asymptomatic women at high risk for ovarian cancer.

OBJECTIVE: Women at high risk of ovarian cancer are currently offered two options: either surveillance or prophylactic bilateral salpingo-oophorectomy. The efficacy and outcome of surveillance remain unclear. METHODS: We performed a retrospective study. Between 1994 and 2000, we screened 383 high-risk women, of which 152 were BRCA1/2 mutation carriers. Surveillance consisted of annual gynecological examination, transvaginal ultrasound, and serum CA125 measurement. Exploratory or prophylactic surgery was performed in selected cases. RESULTS: There were no screen-detected primary ovarian cancers. Abnormal results at surveillance were observed in 74 (19.3%) of women; in 47 (63.5%), the abnormalities disappeared spontaneously. Exploratory surgery was performed in 20 (27.0%) women in whom one malignancy was found (metastatic breast cancer in the ovary). A rising CA125 value prompted further (non-surgical) evaluation in three women with a history of breast cancer: recurrent breast cancer was diagnosed in two women; in the third, a chondrosarcoma was found. 133 women opted for prophylactic bilateral salpingo-oophorectomy, whereby two unexpected malignancies were found (fallopian tube cancer and metastatic breast cancer). One interval primary ovarian cancer occurred, presenting as papillary serous carcinoma of the peritoneum 14 months after prophylactic bilateral salpingo-oophorectomy. Complications of prophylactic surgery were encountered in 15 (11.5%) women. CONCLUSIONS: Ovarian cancer surveillance has limited sensitivity, and a high number of false positive findings. This can lead to unnecessary surgical interventions, possibly resulting in surgery-related complications. It is important to inform high-risk women of these limitations. For now, prophylactic bilateral salpingo-oophorectomy remains the optimal risk-reducing strategy for women at high risk.