[Analysis of synaptonemal complex from a carrier with 46,XY,t(11;18) balanced translocation].
摘要
Over ten years ago, two male patients of pregnancy wastage, who were the carriers of 4;6 and 4;13 reciprocal translocations, respectively, were analyzed with synaptonemal complexes (SCs) by de Perdigo et al. They suggested that the pregnancy wastage should be caused by heterosynapsis, which reciprocal translocations resulted in. The heterosynapsis might avoid spermatogenesis failure, but easily induced non-disjunction of some chromosomes and led to occurrence of unbalanced gametes. A new male patient of the pregnancy wastage was detected in China three years ago. Karyotyping of the patient showed 11;18 reciprocal translocation. Analysis of synaptonemal complexes (SCs) of the patient was performed using the EM technology of SC surface spreading, SDS treatment, AgNO3 staining. The SCs of 30 spermatocytes at pachytenes were analyzed. The SCs in electron micrographs were measured by the method published by de Perdigo et al. (1991). The results showed that each of the observed spermatocytes displayed 20 autosomal bivalents, a quadrivalent 11;18 and a sexual bivalent. Of the 30 spermatocytes, 21 each exhibited a quadrivalent of adequate quality for measurement and interpretation. The 21 quadrivalents were classified into three types: type I, quadrivalents with fully paired arms with the expected cross-configuration, two quadrivalents were of this type. Type II, quadrivalents with an evident heterosynapsis, forming five SC segments (four fully pairing arms and one middle pairing region), six quadrivalents were of this type. Type III, quadrivalents with four paired arms, but with asynapsed regions around the breakpoints, thirteen quadrivalents were of this type. Based on configuration, quadrivalents were classified into cis-configuration with above three types and trans-configuration with above two types except type I. Each of the analyzed quadrivalents showed four synaptic arms, which respectively paired between chromosome 11 and t18 (the translocated 18;11), 18 and t18, 1