Purpose: Vitamin D deficiency has emerged as another potential risk factor for coronavirus disease (COVID‐19) due to the immunomodulatory effects of 25 hydroxyvitamin D [25 (OH)D]. Vitamin D receptor (VDR) gene polymorphisms such as Fok I, Bsm I, Apa I, and Taq I are also associated with different courses of viral infections. This study aimed to evaluate the association between the VDR gene polymorphism at Fok I, Taq I, Bsm I, and Apa I genotypes and the prognosis of COVID‐19 in respect to vitamin D deficiency.Methods: Two‐hundred ninety‐seven patients with COVID‐19 were enrolled. Serum 25 (OH)D levels were measured. Four variant regions of the VDR gene, FokI, BsmI, ApaI, and TaqI were determined.Results: Eighty‐three percent of subjects had vitamin D deficiency, and 40.7% of the whole group had severe deficiency. Median 25 (OH)D level was 11.97 ng/ml. Vitamin D levels were not related to inflammatory markers, disease severity, admission to intensive care unit (ICU), and mortality. While disease severity was related to Fok I Ff genotype, it was Taq TT genotype for ICU admission. Moreover, the ApaI aa genotype was common among the patients who were died. None of the deceased subjects had the Fok I FF genotype.Conclusion: 25 (OH)D levels were not related to the severity and mortality of COVID‐19. VDR gene polymorphisms are independently associated with the severity of COVID‐19 and the survival of patients.

Background: Angiotensin‐converting enzyme 2 and transmembrane protease serine 2 are critical factors of virus transmission. Expression of angiotensin‐converting enzyme 2 is highest in testes, and testicular function and testosterone levels were affected by coronavirus disease 2019. Low testosterone levels are related to infections, especially respiratory tract infections, and could worsen clinical conditions by exacerbating cytokine storms and increasing pro‐inflammatory cytokines.Objectives: We aimed to evaluate the acute and chronic effects of coronavirus disease 2019 on gonadal functions. Our second aim was to detect the relationship between free testosterone levels and disease prognosis and determine the impact of low‐free testosterone on admission to the intensive care unit.Methods: Eighty‐one patients with reverse‐transcription polymerase chain reaction‐confirmed coronavirus disease 2019 were enrolled. Twenty‐nine patients were assessed again for 6 months post‐coronavirus disease 2019 follow‐up, and seven of them had a semen analysis. Serum follicle‐stimulating hormone, luteinizing hormone, sex hormone‐binding globulin, and total testosterone levels were measured.Results: In this observational study, 71.6% (n = 58) of patients had low free testosterone levels at baseline, in which 69% were considered secondary hypogonadism. A longer length of hospitalization and increased inflammatory markers (d‐dimer, high‐sensitive C‐reactive protein, and procalcitonin) were detected in the low‐free testosterone group. Follicle‐stimulating hormone, total, free, and bioavailable testosterone levels were lower in patients who required admission to the intensive care unit. Free testosterone levels were inversely correlated with the length of hospitalization and prognostic disease factors. Oligozoospermia and impaired progressive motility were present in 42.8% (3/7) of the patients. In 6 months post‐coronavirus disease 2019 follow‐up, out of 29 patients, 48.2% still had low testosterone levels.Conclusion: A high rate of hypogonadism (71.6%) was found, especially secondary hypogonadism, and about half of the patients had hypogonadism in the sixth months' follow‐up. Low free testosterone levels were correlated with inflammatory parameters, and it is related to the intensive care unit admission. Studies with long‐term follow‐up data in larger groups are needed to determine persistent hypogonadism and impaired spermatogenesis.

The analysis of extracellular vesicles has been accelerated because of the technological advancements in omics methods in recent decades. Extracellular vesicles provide multifaceted information regarding the functional status of the cells. This information would be critical in case of central nervous system cells, which are confined in a relatively sealed biological compartment. This obstacle is more dramatic in psychiatric disorders since their diagnosis primarily depend on the symptoms and signs of the patients. In this paper, we reviewed this rapidly advancing field by discussing definition of extracellular vesicles, their biogenesis and potential use as clinical biomarkers. Then we focused on their potential use in psychiatric disorders in the context of diagnosis and treatment of these disorders. Finally, we tried to combine the RDoC (Research Domain Criteria) with the use of extracellular vesicles in psychiatry research and practice. This review may offer new insights in both basic and translational research focusing on psychiatric disorders.