| Psoriasis is a well-characterized, inflammatory, hyperoliferative skin disease. Etiological factors have not yet been definite at present. The prevalence rate of psoriasis in natural population has been reported to vary from 0.1%-3%. It affects approximately 2% of prople in northern European and North American white populatios, but it is relatively infrequent, even rare, among blacks, in the Japanese population, and in native North and South American populations. A large investigation found that the prevalence rate was 0.123% in China in 1984. At present, there are more than 300 million patients with psoriasis in our country. There were lots of theory of etiology with regard to psoriasis, such as heredity, obstacle of metabolism, infection and obstacle of immunological function and so on is possibly important induced factors. As for its genetic model has not been definitely concluded at present. The purpose of this study was to explore the effects of genetic factors on the onset of psoriasis vulgaris and the possible genetic model of psoriasis.1043 patients with psoriasis vulgaris were studied by questionnaire and follow-up. The complex segregation analysis and heritability was performed, with the aid of Penrose's method, Falconer's, Epi info 6.0 and SAGE-REGTL program. The results showed that CD For the male and female patients, the peak ages of the first onset were and years , respectively.(2)In 1043 psoriatics, 308 cases (29.5%) reported to have a family history of psoriasis. The age of onset was earlier in man with family history than that in man without family history (p<0.01), but the female patients did not. The age of onset was early 8.4 years in psoriatics, whose fathers and /or mothers suffering from psoriasis than that in psoriatics with normal parents (p<0.05). (3)The number of cases with type I psoriasis (early onset, ageof the first onset < 40) was 899(86.19%), and that with type II (late onset, age of the first onset >40) was 144 (13.81%). The morbidities of first-degree relatives were 7.67% in type I psoriatic and 5.27% in type II (p<0.01), and those of second-degree relatives were 1.04% in types I psoriatic and 0.17% in type II (p<0.01). The onset of psoriasis was earlier in the females than that in the males in type I psoriasis (p<0.01), but it was not the same in type II (p>0.05).(4)Prevalence of psoriasis in first-degree and second-degree relatives of the proband with psoriasis was 7.68%,0.90% respectively, which were higher than that in general population(0.146%)(5)A ratio of s/q approached 1/Vq with Penrose's method, and the heritability of psoriasis in first-degree and second-degree relatives was 67.04%,46.6% respectively. Mendelian, No-major-gene and Environment model was rejected by complex segregation analysis. Conclusion it suggests that psoriasis vulgaris follows a pattern of polygenetic or multifactorial inheritance rather than single-gene one, and the genetic factors play an important role in the pathogenesis.
|
PDF Full Text Request