| Background Psoriasis is a common chronic inflammatory and hyperproliferative skin disease with a strong genetic component. Psoriasis vulgaris is the most common type (>90%). Prevalence rates of psoriasis ranges from 0 to 3% and shows a wide variability between different ethnic groups [1] The estimated prevalence rate of psoriasis is about 2% in the USA and northern Europe [2] In China, psoriasis affects 0.123% of the population and there have been more than 3 million cases reported since 1984[3]. In our recent studies, prevalence rate of psoriasis vulgaris in first-degree and second-degree relatives of the proband with psoriasis was 7.24% and 0.95% respectively, which were higher than that in general population [4]. A significant genetic component to psoriasis susceptibility has long been supported by observations of family disease clustering, elevated concordance rates amongst monozygous twins [5]. Over the last few years, a number of research groups have pursued major studies investigating the molecular genetic basis of psoriasis. Particular attention is given to the genetic analysis of the major histocompatibilty complex on human chromosome 6, a region subject to intense scrutiny [6,7]. Up to now, various HLA associations have been reported. There are increased frequencies of class I antigens HLA-A1, A2, A30, B13, B17, B37, B*57, B39, B46, Cw6, Cw7, Cw9, Cw11, and class II antigens DQA1*0201,DQB1*0303, DRB1*0701/02,DRB1*1401. [8,9,10,11] This relationship, however, tends to vary between patients of different racial and ethnic backgrounds [12,13l. During the past over 20 years, it was reported that the frequencies of several HLA antigens including Al, B13, B17, Cw4, Cw6 and DQB 1*0602, DRB 1*0701/02 were increased in PV in Chinese Hans [14]. In linkage disequilibrium analysis, certain alleles occur together more frequently than expected by chance; some risk or protective haplotypes were reported in different ethnical groups l19'26-28-29'30-'1^ Objective To identify special haplotypes in Chinese Hans that may contribute to the genetic susceptibility to PV. Material and Methods One hundred and thirty-eight psoriasis vulgarispatients and 149 non-psoriatic controls were typed for HLA- A, B, C, DQA1, DQB1, DRB1 by using the polymerose chain reaction sequence-specific primer (PCR-SSP) technique. Results (l)The allele frequencies of HLA-A*26 (26.09%vsl2.08%,OR=3.42,P<10-6,Pc<10-5) ,-B*27 (17.03%vsl.01%,OR=25.14,P<10-7,Pc<10-7) ,-Cw*0602 (15.58%vs5.03%,OR=4.04,P<10'5,Pc <10-2),-DQAl*0104(19.93%vs9.04%,OR=2.86,P<10-5,Pc<10-3),-DQAl*0201 (22.40%vsl0.74 %,OR=2.98,P<10-5,Pc<10-3), DQB1*0303 (l8.l2%vs9.73%,OR=4.65,P<10-7,Pc |
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