Whole exome sequencing revealed novel pathogenic variants in Vietnamese patients with FEVR.

Background: Familial exudative vitreoretinopathy (FEVR) is a rare inherited disorder marked by incomplete retinal vascularization associated with exudation, neovascularization, and tractional retinal detachment. FEVR is genetically heterogeneous and is caused by variants in six genes: FZD4, LRP5, NDP, TSPAN12, ZNF408, and CTNNB1. In addition, the phenotypic overlap between FEVR and other disorders has been reported in patients harboring variants in other genes, such as KIF11, ATOH7, and RCBTB1. Purpose: To identify pathogenic variants in Vietnamese pediatric patients diagnosed with FEVR and to investigate the clinical findings in correlation with each causative gene. Methods: A total of 20 probands underwent ocular examinations with fundoscopy (ophthalmoscopy) or fluorescein angiography. Genomic DNA was extracted from the peripheral blood of the probands and their family members. Multiplex ligation-dependent probe amplification (MLPA) was employed to detect copy number variants of FEVR-causing genes. Short variants were screened by whole-exome sequencing (WES) and then validated by Sanger sequencing. Results: Fluorescein angiography showed retinal vascular anomalies in all patients. Other ocular abnormalities commonly found were strabismus, nystagmus, exudation, and retinal detachment. Genetic analysis identified 12 different variants in the FZD4, NDP, KIF11, and ATOH7 genes among 20 probands. Four variants were novel, including FZD4 c.169G>C, p.(G57R); NDP c.175-3A>G, splicing; KIF11 c.2146C>T, p.(Q716*) and c.2511_2515del, p.(N838Kfs*17). All patients with the KIF11 variant showed signs of microcephaly and intellectual disability. The patient with Norrie syndrome and their family members were found to have a deletion of exon 2 in the NDP gene. Conclusions: This study sheds light on the genetic causes of ocular disorders with the clinical expression of FEVR in Vietnamese patients. WES was applied as a comprehensive tool to identify pathogenic variants in complex diseases, such as FEVR, and the detection rate of pathogenic mutations was up to 60%.

Thermohydraulic performance augmentation in a solar air heater using a perforated circular segment vortex generator.

Hybrid turbulators have been introduced as a feasible solution to improve heat transfer in fluid channels. In this study, a perforated circular segment was used as a vortex generator to enhance the heat transfer rate in an air collector duct. The effects of key parameters, including Reynolds numbers ranging from 6000 to 18,000 (four values), angles of attack from 30 to 90° (five values), and inline and staggered segment arrangements, on heat transfer, pressure loss, and thermohydraulic performance were investigated. A 3D numerical simulation using the RNG k-ε turbulence model with experimental verification was performed in this study. The results showed that the maximum thermohydraulic performance parameter was 1.3, and an attack angle of 30° provided the best performance. Strong turbulence occurred with an angle of attack of 60°, which caused a large pressure loss in comparison with the heat transfer enhancement. The maximum turbulence kinetic energy shifted from the root to the peak of a segment when the angle of attack increased. The Nusselt number and friction factor of the staggered configuration were 1.72 times and 1.88 times the corresponding values of the inline arrangement.