NOD2 Versus MEFV: Differential Diagnosis of Yao Syndrome and Familial Mediterranean Fever.

Objectives: Yao syndrome (YAOS, OMIM 617321) was formerly designated as nucleotide-binding oligomerization domain-containing protein-2 (NOD2)-associated autoinflammatory disease (NAID). This disorder shares similar clinical phenotypes with hereditary periodic fever syndromes (HPFS). This study aimed to compare YAOS with familial Mediterranean fever (FMF). Methods: In this retrospective study, electronic medical records of a case series of YAOS were reviewed and data were analyzed. All patients underwent genetic testing for periodic fever syndrome 6-gene panel. Results: A total of 6 cases were presented. These patients were initially thought to have MEditerranean FeVer (MEFV)-negative FMF and received treatment with colchicine. They were eventually diagnosed with YAOS. The differences between these diseases were illustrated. In addition, both MEFV and NOD2 mutations were detected in some patients and family members. Patients with carriage of both gene mutations may present with heterogeneous disease expression. A close correlation between phenotypes and genotypes is needed to make a diagnosis. Conclusions: YAOS may mimic FMF. Molecular analysis should cover NOD2 whole gene sequencing to help distinguish these diseases. Both NOD2 and MEFV mutations may contribute to disease expression in an individual.