Craddock N, McGuffin P
Department of Psychological Medicine, University of Wales College of Medicine, Cardiff, U.K.
Ann Med. 1993 Aug;25(4):317-22. doi: 10.3109/07853899309147291.
Affective (mood) disorders are common. There are several methodological impediments to genetic studies of affective disorders, including uncertainties about the best definition of disease phenotype, difficulties in the assessment of lifetime diagnosis and variable age of onset of illness. Despite these difficulties, family, twin and adoption studies provide compelling evidence for the existence of important genetic factors in determining susceptibility to affective disorders. However, the mode of inheritance is unknown. Simple mendelian inheritance may occur in some families but cannot explain the majority of cases. With the advent of polymorphic DNA markers, linkage and association studies have become more useful methods for the genetic analysis of complex disorders such as affective illness. No consistent finding has yet emerged, although chromosomal region 11p15 (and to a lesser extent Xq28) are of continuing interest. In addition to further study of these regions it will also be necessary to look for susceptibility loci in other parts of the genome. Large samples will almost certainly be required. If susceptibility loci of major effect exist then linkage approaches will find them. However, if there are only loci of small effect, then association approaches will be necessary. At present, it seems prudent to pursue both linkage and association approaches together.
情感（心境）障碍很常见。情感障碍的遗传学研究存在一些方法学上的障碍，包括疾病表型的最佳定义存在不确定性、终生诊断评估困难以及发病年龄各异。尽管存在这些困难，但家族、双生子和收养研究为确定情感障碍易感性时重要遗传因素的存在提供了令人信服的证据。然而，遗传模式尚不清楚。简单的孟德尔遗传可能在一些家族中出现，但无法解释大多数病例。随着多态性DNA标记的出现，连锁和关联研究已成为对情感疾病等复杂疾病进行遗传分析的更有用方法。尽管11p15染色体区域（以及程度较轻的Xq28）一直备受关注，但尚未出现一致的研究结果。除了对这些区域进行进一步研究外，还需要在基因组的其他部位寻找易感基因座。几乎肯定需要大样本。如果存在主要效应的易感基因座，那么连锁研究方法将会找到它们。然而，如果只有小效应基因座，那么关联研究方法将是必要的。目前，同时采用连锁和关联研究方法似乎是审慎之举。
