A number sign (#) is used with this entry because of evidence that susceptibility to Yao syndrome (YAOS) is conferred by variation in the NOD2 gene (605956) on chromosome 16q12.

Yao syndrome (YAOS) is an autoinflammatory disease characterized by periodic fever, dermatitis, arthritis, and swelling of the distal extremities, as well as gastrointestinal and sicca-like symptoms. The disorder is associated with specific NOD2 variants (Yao and Shen, 2017).

Yao et al. (2011) described 7 unrelated patients with apparent autoinflammatory disease with multisystem involvement. Mean age at disease onset was 40.7 years, and the patients characteristically presented with periodic fever, dermatitis, and inflammatory polyarthritis. Cutaneous features included pruritic or nonpruritic erythematous edematous plaques, patches, macules, papules, and linear scratch-like rash of the face, chest, abdomen, and limbs. There were gastrointestinal symptoms (pain and/or diarrhea) in 3 patients, with granulomas of the gut in 1; however, there was no radiographic, endoscopic, or histologic evidence of Crohn disease (see 266600). Recurrent chest pain occurred in 2 patients, with 1 having pleuritis and pericarditis. Three patients had sicca-like symptoms, with blurred vision and dry eyes; examination excluded uveitis in all 3, and Sjogren syndrome (270150) evaluation was negative.

Yao et al. (2013) studied 22 patients with autoinflammatory disease, including the 7 previously reported by Yao et al. (2011). Mean age at diagnosis was 40 years, with a range from age 17 to 72 years, and mean disease duration of 4.7 years. Of the 22 patients, 20 (90.9%) had arthritis or arthralgia, and 19 (86.4%) had skin manifestations; weight loss, episodic self-limiting fever, and/or gastrointestinal (GI) symptoms were present in 13 (59.1%), dry eyes and mouth in 9 (40.9%), chest pain in 5 (22.7%), and pulmonary parenchymal disease in 3 (13.6%). None of the patients exhibited uveitis. Laboratory evaluation revealed that 9 patients had an elevated sedimentation rate and/or C-reactive protein level; however, none of the patients showed serologic evidence of systemic autoimmune disease. Yao et al. (2013) stated that this disorder differs markedly from Blau syndrome (186580), with the dermatitis being spongiotic rather than granulomatous, and without the chronic joint deformity (camptodactyly) and uveitis seen in Blau syndrome. In addition, Blau syndrome lacks GI manifestations, whereas approximately 60% of patients studied by Yao et al. (2013) had GI symptoms.

Yao et al. (2015) reported that 54 of 143 patients with a clinical phenotype suggestive of Yao syndrome had variants in the NOD2 gene. Forty-nine (91%) of the patients with NOD2 variants had intermittent skin symptoms, primarily erythematous patches and plaques. Twenty patients underwent skin biopsy, which showed spongiotic dermatitis in 7, granulomatous changes in 4, perivascular dermatitis in 4, and 'other dermatitis' in 4. Arthritis and/or arthralgia was present in 47 (87%) of the patients, and 39 (72%) reported recurrent intermittent abdominal pain and/or diarrhea of varying degrees. Recurrent fever occurred in 33 (61%) of the patients, dry eyes and/or dry mouth in 30 (56%), and lower extremity swelling in 17 (32%). In addition, 9 (14%) patients experienced recurrent chest pain, with 5 having pleuritis and/or pericarditis.

Yao and Kontzias (2022) described 11 patients with YAOS. All of the patients had an autoinflammatory phenotype including skin rash, arthralgia, and gastrointestinal symptoms. Most of the patients also had ocular manifestations, including 7 with eyelid swelling and 6 with sicca. Eight patients experienced fevers, 4 had chest pain, 5 had asthma, and 7 had elevated acute phase reactants (erythrocyte sedimentation rate, C-reactive protein).

Yao and Shen (2017) outlined diagnostic criteria for Yao syndrome, of which the 2 major criteria were periodic occurrence at least twice, and recurrent fever and/or dermatitis. Four minor criteria included oligo- or polyarthralgia/inflammatory arthritis, or distal extremity swelling; abdominal pain and/or diarrhea; sicca-like symptoms; and pericarditis and/or pleuritis. The molecular criterion consisted of the presence of NOD2 rare variants; and exclusion criteria included high titer antinuclear antibodies, inflammatory bowel disease, Blau syndrome, adult sarcoidosis, primary Sjogren syndrome, and monogenic autoinflammatory diseases. Patients were designated as having Yao syndrome if they met the 2 major criteria and one or more minor criteria, as well as the molecular and exclusion criteria.

Yao et al. (2015) stated that Yao syndrome is common relative to other autoinflammatory diseases in the American adult population, with an estimated population prevalence of 1 to 10 per 100,000.

In 7 unrelated patients with multisystem autoinflammatory disease, 5 of whom were negative for mutation in the periodic fever-associated genes TNFRSF1A (191190) and/or MEFV (608107), Yao et al. (2011) identified heterozygosity for a known intronic variant in the NOD2 gene, IVS8+158 (605956.0007). Four of the patients also carried the R702W variant in NOD2 (605956.0003). Yao et al. (2011) stated that the clinical relevance of these gene mutations remained to be determined, and that this disease might be genetically complex rather than mendelian.

In 22 patients with autoinflammatory disease, including the 7 patients previously studied by Yao et al. (2011), Yao et al. (2013) screened the NOD2 gene and found that all carried at least 1 variant: 21 had the IVS8+158 variant, and 8 had the R702W variant. Ten of the patients were tested for mutations in other autoinflammation-associated genes, including TNFRSF1A, MEFV, and NLRP3 (606416), with negative results.

Yao et al. (2015) genotyped 143 patients with symptoms suggestive of Yao syndrome for NOD2 variants and identified 54 patients who fulfilled criteria for Yao syndrome, including the presence of NOD2 variants. The IVS8+158 variant was detected in 46 of the 54 patients, including 30 who carried only IVS8+158 and 18 who also carried other known variants, including R702W, 3020insC (605956.0001), and G908R (605956.0002). In addition, 9 other rare NOD2 variants were detected in 13 of the patients. Yao et al. (2015) noted that it remained unclear whether these variants were causative or served as markers indirectly associated with the disease.

Yao and Kontzias (2022) identified mutations in the NOD2 gene in 11 patients with YAOS; 5 patients had a single mutation (3 with IVS8+158), 5 patients had biallelic mutations (all with IVS8+158 on 1 allele), and 1 patient had 3 mutations. The mutations were identified by next-generation sequencing of a panel of genes associated with periodic fever syndromes.