Davis J O, Phelps J A
Dept. of Psychology, Southwest Missouri State University, Springfield 65804-0027, USA.
Schizophr Bull. 1995;21(1):13-8. doi: 10.1093/schbul/21.1.13.
High concordance for schizophrenia in monozygotic (MZ) twins is often cited as evidence for the etiological influence of genetics; however, even if twins are separated at birth, MZ twin concordance is influenced by the shared prenatal environment. Study of the placentation status of MZ twins provides a way to investigate some prenatal influences, including the possible role of viral infections. The probability of shared infections is likely to be greater in monochorionic MZ twin pairs than in dichorionic pairs because of shared fetal circulation in the monochorionic pairs. We drew from published twin studies and used reported concordance for handedness as a retrospective marker of placentation status. We found that MZ twin pairs with opposite-hand preferences were concordant for psychosis in 9 of 15 cases (60%), while only 18 of 56 twin pairs (32%) with same-hand preferences were concordant for psychosis. These results suggest that shared prenatal viral infection may account for much of the high concordance for schizophrenia in identical twins.
同卵双胞胎中精神分裂症的高一致性常被引为遗传学病因影响的证据；然而，即使双胞胎在出生时就分开，同卵双胞胎的一致性仍受共享的产前环境影响。对同卵双胞胎胎盘形成状态的研究提供了一种调查某些产前影响的方法，包括病毒感染的可能作用。由于单绒毛膜双胞胎对中存在共享的胎儿循环，单绒毛膜同卵双胞胎对中共享感染的可能性可能比双绒毛膜双胞胎对更大。我们借鉴已发表的双胞胎研究，并将报告的利手一致性用作胎盘形成状态的回顾性标记。我们发现，15例中9例（60%）利手偏好相反的同卵双胞胎对在精神病方面具有一致性，而56例利手偏好相同的双胞胎对中只有18例（32%）在精神病方面具有一致性。这些结果表明，共享的产前病毒感染可能是同卵双胞胎中精神分裂症高一致性的主要原因。
