Coco R, Rahn M I, Estanga P García, Antonioli G, Solari A J
FECUNDITAS, Instituto de Medicina Reproductiva, Larrea 790, Buenos Aires, Argentina.
Hum Reprod. 2004 Dec;19(12):2784-90. doi: 10.1093/humrep/deh506. Epub 2004 Oct 28.
Complex chromosome rearrangements are rare aberrations that frequently lead to reproductive failure and that may hinder assisted reproduction. A 25-year-old azoospermic male was studied cytogenetically with synaptonemal complex analysis of spermatocytes from a testicular biopsy and fluorescence in situ hybridization (FISH) of lymphocytes. The spermatocytes showed a pentavalent plus a univalent chromosome. Cell death occurred mainly at advanced pachytene stages. The sex chromosomes were involved in the multiple, as shown by their typical axial excrescences. Two autosomal pairs, including an acrocentric chromosome (15), were also involved in the multiple. FISH allowed the definite identification of all the involved chromosomes. An inverted chromosome 12 is translocated with most of one long arm of chromosome 15, while the centromeric piece of this chromosome 15 is translocated with Yqh, forming a small marker chromosome t(15;Y). The euchromatic part of the Y chromosome is joined to the remaining piece of chromosome 12, forming a neo-Y chromosome. The patient shows azoospermia and a normal phenotype. The disruption of spermatogenesis is hypothetically due to the extent of asynaptic segments and to sex-body association during pachytene. This CCR occurred 'de novo' during paternal spermatogenesis. Meiotic analysis and FISH are valuable diagnostic tools in these cases.
复杂染色体重排是罕见的畸变，常导致生殖失败，并可能阻碍辅助生殖。对一名25岁的无精子症男性进行了细胞遗传学研究，对睾丸活检的精母细胞进行联会复合体分析，并对淋巴细胞进行荧光原位杂交（FISH）。精母细胞显示一个五价体加一个单价染色体。细胞死亡主要发生在粗线期晚期。性染色体参与了多重排列，表现为典型的轴向赘生物。两个常染色体对，包括一个近端着丝粒染色体（15号染色体），也参与了多重排列。FISH能够明确鉴定所有涉及的染色体。一条倒位的12号染色体与15号染色体的大部分长臂发生易位，而这条15号染色体的着丝粒片段与Yqh发生易位，形成一个小的标记染色体t(15;Y)。Y染色体的常染色质部分与12号染色体的剩余片段相连，形成一条新Y染色体。该患者表现为无精子症且表型正常。推测精子发生的破坏是由于粗线期非联会片段的长度以及性体关联。这种复杂染色体重排在父本精子发生过程中“从头”发生。减数分裂分析和FISH在这些病例中是有价值的诊断工具。
