NDT Advance Access originally published online on September 17, 2006
Nephrology Dialysis Transplantation 2007 22(1):196-202; doi:10.1093/ndt/gfl504
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Changes in fat mass after initiation of maintenance dialysis is influenced by the uncoupling protein 2 exon 8 insertion/deletion polymorphism
1Divisions of Baxter Novum and Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden, 2Institute of Nephrology, First Hospital, Peking University, Beijing, PR China and 3Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
Correspondence and offprint requests to: Peter Stenvinkel, MD, PhD, Divisions of Renal Medicine and Baxter Novum, Karolinska Institutet, K-56 Karolinska University Hospital Huddinge, 141 86 Stockholm, Sweden. Email: peter.stenvinkel{at}ki.se
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Abstract |
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Background. A high body mass index (BMI) has been reported to confer a survival advantage in end-stage renal disease (ESRD) patients. On the other hand, body fat accumulation, especially visceral adipose tissue, is an important risk factor for cardiovascular disease, as well as a clinically important source of adipokines. Uncoupling protein 2 (UCP2) uncouples respiration from ATP synthesis, thus regulating energy expenditure and fat oxidation. In this longitudinal cohort study, we investigated the impact of the UCP2 insertion/deletion (ins/del) polymorphism on body composition changes in ESRD patients starting dialysis.
Methods. A total of 222 incident Caucasian ESRD patients (mean age 53 ± 12 years; 60% males) were investigated close to the start of dialysis with peritoneal dialysis (PD; n = 126) or haemodialysis (HD; n = 96), and again after about 1 year (n = 159). Genotyping of the UCP2 ins/del polymorphism was performed in the patients and in 207 healthy controls. Dual-energy X-ray absorptiometry was conducted at baseline and after 1 year to monitor body composition.
Results. While HD patients and PD patients with the ins/del genotype did not display any changes in body composition, the 48 PD patients with the del/del genotype that completed follow-up had a significant increase; 
BMI (0.7 ± 1.8 kg/m2), body fat mass (3.5 ± 3.8 kg) and truncal fat mass (1.7 ± 1.2 kg). In a multiple linear regression analysis, the del/del genotype was an independent predictor of the increase in truncal fat mass in PD patients (F-ratio = 7.99, P < 0.05) together with age and diabetes mellitus.
Conclusions. PD patients, but not HD patients, with the UCP2 del/del genotype showed a significant increase in total and truncal fat mass during the first year of dialysis therapy, suggesting a possible role for UCP2 in dissipating the excess energy of a high-glucose environment.
Keywords: body composition; dialysis; fat mass; polymorphism; UCP2