Mental retardation (MR) is a group of common and complex disabilities affecting the central nervous system and appears before the period of brain developmental maturity. Recently, only 40% of genetic MR has been identified, however 60% remains unexplained. In this study, we applied exome sequencing to identify the mutation p.R430X in UPF3B gene in an MR pedigree, which was validated by Sanger sequencing and completely cosegregated within this family. UPF3B gene encodes a protein involved in nonsense-mediated mRNA decay (NMD). By real-time quantitative PCR, we detected the significant difference in the mRNA expression levels of the UPF3B and the classical NMD pathway target growth arrest and DNA-damage-inducible-beta (GADD45B) between the patients and the controls. Our results directly implicated that the mutation p.R430X in UPF3B gene was the genetic etiology of the MR pedigree.

Objective:Recent observational studies have reported that body fat distribution might be differentially associated with subclinical atherosclerosis. We previously reported that visceral fat area (VFA) ⩾80 cm2 is the optimal cutoff for identifying abdominal obesity in Chinese subjects. We examined whether VFA ⩾80 cm2 reflects the association between abdominal obesity and subclinical atherosclerosis, and if determination of the visceral fat quantity is useful for assessing subclinical atherosclerosis in asymptomatic individuals.Methods and results:Participants (N=1005, men 515, women 490, 34–66 years) free of cardiovascular disease underwent magnetic resonance imaging and carotid ultrasound assessment to quantify VFA and carotid intima–media thickness (C-IMT). Overweight/obese subjects (body mass index (BMI) ⩾25.0 kg m−2) had a higher C-IMT than lean subjects (BMI <25.0 kg m−2) (P<0.01). Subjects with VFA ⩾80 cm2 had significantly higher C-IMT than those without abdominal obesity regardless of BMI (P<0.01). By multivariate regression analysis adjusted for anthropometric measurements and cardiovascular risk factors, waist circumference but not BMI was independently correlated with C-IMT in men (P<0.001). Similar findings were observed with an accurate obesity indices adjusted model, which showed that VFA was an independent risk factor for increased C-IMT in men but not in women.Conclusions:VFA ⩾80 cm2 effectively identified carotid atherosclerosis for both lean and obese individuals in middle-aged Chinese men.