tailieunhanh - AN ATLAS OF SCHIZOPHRENIA - PART 4

Cuối cùng, Ngay cả Nếu không điều trị, triệu chứng tâm thần phân liệt cấp tính của các thường giải quyết. Thật không may này có nghĩa là không phải lúc nào đó không bệnh nhân sẽ bình phục hoàn toàn. Hơn 50% bệnh nhân chẩn đoán là đau khổ từ tâm thần phân liệt sẽ cho thấy bằng chứng về một mức độ đáng kể | Relationship s Percentage chizophrenic Parent Sibling Sibling and one parent affected Children of one affected parent Children of two affected parents Uncles aunts nephews nieces Grandchildren Unrelated Table Lifetime expectancy of broadly defined schizophrenia in the relatives of schizophrenics. Table reproduced with permission from Kendell RE Zealley AK. Companion to Psychiatric Studies. Edinburgh Churchill Figure A pair of monozygotic twins discordant for schizophrenia. The twin on the right has schizophrenia GENETICS The most important risk factor for schizophrenia is having an affected relative Figure and Table 3-5. Twin and adoption studies have been used to show that this is consequent upon genetic transmission. The consistently greater concordance in monozygotic MZ than dizygotic DZ twins4-10 Figure has been taken to indicate a genetic effect but does not prove this beyond doubt since MZ twins may be treated more similarly by their parents Figure . However adoption studies have demonstrated conclusively that liability to schizophrenia is transmitted through genes and not through some intrafamilial environmental effect Figure 11 12. Various models of genetic transmission of schizophrenia have been considered but found not to fit the data. There is no evidence to support the single major locus model which implies that a gene of major effect causes schizophrenia but has incomplete penetrance or variable expression. The polygenic model implies that there are many contributing genes while the multifactorial model postulates that there are both genetic and environmental factors. The so-called multifactorial polygenic model involves an interaction between multiple loci and environmental factors with schizophrenia being expressed only in individuals who exceed a certain threshold of liability. Although the mode of transmission has not been absolutely clarified molecular and genetic epidemiological .