MONOZYGOTIC TWINNING AND STRUCTURAL DEFECTS
MONOZYGOTIC TWINNING AND STRUCTURAL DEFECTS
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DOI：
10.1016/s0022-3476(79)80278-4
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发表时间：
1979-01-01
影响因子：
5.1
通讯作者：
MILLER, JR
中科院分区：
文献类型：
--
作者：
SCHINZEL, AAGL;SMITH, DW;MILLER, JR
与双卵双胞胎或单胞胎相比，单卵双胞胎的结构缺陷过多。过剩由三类缺陷组成。第一种包括作为MZ孪晶的一部分的缺陷，例如连体孪晶和一些非晶孪晶。此外，所有早期胚胎畸形和畸形复合体，如sirenomelia mc，无前脑畸形mc和无脑畸形mc在同卵双胞胎中增加。这种关联的原因被认为是MZ双胞胎和早期畸形问题的共同病因。MZ双胞胎提供了一个很好的模型来欣赏特定的畸形复合体的光谱，因为双胞胎往往有不同的严重程度的同一类型的结构缺陷。Goldenhar综合征、de Lange综合征和Rubinstein-Taybi综合征的不一致和一致MZ双胞胎的发现表明，这些“综合征”可能是早期畸形综合征。其他两类被认为是次要的MZ孪生过程。最独特的类别是由同卵双胞胎之间的任何血管交换引起的。根据其性质，血管连接可能会在早期发育期间引起双胞胎中一个心脏状态的反向流动，或者在存活的双胞胎中引起血管内凝血引起死亡双胞胎的血管破裂。后者的缺陷可能包括小头畸形、脑穿通囊肿、积水性无脑畸形、肠闭锁、皮肤发育不全和截肢。不均匀生长可能是动脉-静脉胎盘异位的结果。最后一类是由于妊娠晚期子宫内拥挤引起的畸形。这些与DZ双胞胎没有区别。
An excess of structural defects occurs in monozygotic twins compared to dizygotic twins or singletons. The excess is composed of three categories of defects. The first includes defects which are part of the MZ twinning, such as conjoined twins and some amorphous twins. In addition, all early embryonic malformations and malformation complexes such as sirenomelia mc, holoprosencephaly mc, and amencephaly mc are increased in MZ twins. The reason for this association is considered to be the common etiology for both the MZ twinning and the early malformation problem. MZ twins provide an excellent model for appreciating the spectra of particular malformation complexes, since the twins often have different gradations in severity of the same type of structural defect. The finding of both discordant and concordant MZ twins with Goldenhar, de Lange, and Rubinstein-Taybi syndromes suggests that these “syndromes” might be early malformation complexes. The other two categories are considere secondary to the MZ twinning process. The most unique category results from any vascular interchange between the MZ twins. Depending on their nature, vascular connections may give rise to reverse flow with acardiac status in one twin during early development, or to vascular disruptions from a deceased co-twin with intravascular coagulation causing embolization in the surviving co-twin. The latter defects may include microcephaly, porencephalic cysts, hydranencephaly, intestinal atresia, aplasia cutis, and limb amputation. Unequal growth may occur as a result of artery to vein placental anastomoses. The final category is deformations due to crowding in utero during late gestation. These do not differ from those in DZ twins.