Coronavirus disease 2019 (COVID‐19) is an infectious disease, and the reason behind the currently ongoing pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). Angiotensin‐converting enzyme (ACE2) has been recognized as the specific receptor of the SARS‐CoV‐2 virus. Although the possible effect of ACE2 gene polymorphism remains unknown, human ACE2 receptor expression influences SARS‐CoV‐2 susceptibility and COVID‐19 disease outcome. In this study, we aimed to investigate the relationship between ACE gene I/D polymorphism, ACE2 receptor gene polymorphism, and COVID‐19 severity. ACE gene insertion/deletion (I/D) polymorphism and ACE2 receptor gene rs2106809 and rs2285666 polymorphisms were determined using polymerase chain reaction (PCR) and PCR‐based restriction fragment length polymorphism methods, respectively, in 155 COVID‐19 patients who were divided into three groups (mild, moderate, and severe) according to clinical symptoms. However, the distribution of genotype and allele frequencies of ACE gene I/D, ACE2 receptor gene rs2106809, and rs2285666 polymorphisms were not statistically significant in all groups. In conclusion, in the study population, ACE gene I/D, ACE2 receptor gene rs2106809, and rs2285666 polymorphisms were not associated with the severity of COVID‐19 infection. Although ACE2 receptor gene expression may affect the susceptibility to COVID‐19, there is no existing evidence that the ACE or ACE2 gene polymorphisms are directly associated with COVID‐19 severity. Interindividual differences in COVID‐19 severity might be related to epigenetic mechanisms of ACE2 receptor gene expression or variations in other genes suggested to play a critical role in COVID‐19 pathogenesis such as pro‐inflammatory cytokines and coagulation indicators.

The occurrence of frequent MEFV mutations in BD patients suggests that the MEFV gene is involved in the pathogenesis of Behçet's disease.

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We used exome sequencing of blood DNA in four unrelated patients to identify the genetic basis of metaphyseal chondromatosis with urinary excretion of D-2-hydroxy-glutaric acid (MC-HGA), a rare entity comprising severe chondrodysplasia, organic aciduria, and variable cerebral involvement. No evidence for recessive mutations was found; instead, two patients showed mutations in IDH1 predicting p.R132H and p.R132S as apparent somatic mosaicism. Sanger sequencing confirmed the presence of the mutation in blood DNA in one patient, and in blood and saliva (but not in fibroblast) DNA in the other patient. Mutations at codon 132 of IDH1 change the enzymatic specificity of the cytoplasmic isocitrate dehydrogenase enzyme. They result in increased D-2-hydroxy-glutarate production, a-ketoglutarate depletion, activation of HIF-1a (a key regulator of chondrocyte proliferation at the growth plate), and reduction of N-acetylaspartyl-glutamate level in glial cells. Thus, somatic mutations in IDH1 may explain all features of MC-HGA, including sporadic occurrence, metaphyseal disorganization, and chondromatosis, urinary excretion of D-2-hydroxy-glutaric acid, and reduced cerebral myelinization.

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