OBJECTIVE: We investigated the distribution of MICA triplet repeat polymorphism in a random population and in patients with seronegative spondyloarthritis from Sardinia compared to continental Italy. METHODS: We analyzed the distribution of MICA triplet repeat polymorphism in HLA-B*2709 [not associated with ankylosing spondylitis (AS)] and B*2705 (associated with AS) haplotypes, to verify whether the strong association of MICA-A4 with HLA-B27 reported in other populations is maintained in Sardinia, and compared the distribution of MICA-A alleles in HLA-B27 negative versus HLA-B27+ patients with AS. RESULTS: We found that the frequency of MICA-A4 triplet repeat allele in a random Sardinia population is higher (53.2%) than in other Caucasian populations (around 20%); this allele is strongly associated with both HLA-B*2709 and B*2705. No significant difference between HLA-B27+ patients with AS and healthy controls was found: the MICA-A4 allele was present in more than 90% of subjects. MICA-A4 was found in 16 out of 20 HLA-B27 negative Sardinian patients with AS, with a frequency (80%) more similar to that of the HLA-B27+ group of patients than that of controls. CONCLUSION: The high frequency of MICA-A4 allele in HLA-B27 negative patients with AS from Sardinia, suggests the presence within the HLA region of a susceptibility factor other and certainly weaker than B27. This factor is likely to be more easily found by analyzing genetically homogeneous populations like the Sardinian, characterized by a small number of very frequent haplotypes.
OBJECTIVE: We investigated the distribution of MICA triplet repeat polymorphism in a random population and in patients with seronegative spondyloarthritis from Sardinia compared to continental Italy. METHODS: We analyzed the distribution of MICA triplet repeat polymorphism in HLA-B*2709 [not associated with ankylosing spondylitis (AS)] and B*2705 (associated with AS) haplotypes, to verify whether the strong association of MICA-A4 with HLA-B27 reported in other populations is maintained in Sardinia, and compared the distribution of MICA-A alleles in HLA-B27 negative versus HLA-B27+ patients with AS. RESULTS: We found that the frequency of MICA-A4 triplet repeat allele in a random Sardinia population is higher (53.2%) than in other Caucasian populations (around 20%); this allele is strongly associated with both HLA-B*2709 and B*2705. No significant difference between HLA-B27+ patients with AS and healthy controls was found: the MICA-A4 allele was present in more than 90% of subjects. MICA-A4 was found in 16 out of 20 HLA-B27 negative Sardinian patients with AS, with a frequency (80%) more similar to that of the HLA-B27+ group of patients than that of controls. CONCLUSION: The high frequency of MICA-A4 allele in HLA-B27 negative patients with AS from Sardinia, suggests the presence within the HLA region of a susceptibility factor other and certainly weaker than B27. This factor is likely to be more easily found by analyzing genetically homogeneous populations like the Sardinian, characterized by a small number of very frequent haplotypes.
Authors: John D Reveille; Xiaodong Zhou; MinJae Lee; Michael H Weisman; Lin Yi; Lianne S Gensler; Hejian Zou; Michael M Ward; Mariko L Ishimori; Thomas J Learch; Dongyi He; Mohammad H Rahbar; Jiucun Wang; Matthew A Brown Journal: Ann Rheum Dis Date: 2018-10-19 Impact factor: 19.103
Authors: Harry Petrushkin; Md Samiul Hasan; Miles R Stanford; Farida Fortune; Graham R Wallace Journal: Front Immunol Date: 2015-03-24 Impact factor: 7.561