Pereira S R F, Pereira A C N, Souza M T V L, Ramos M R B P
Departamento de Biologia, Laboratório de Genética e Biologia Molecular, Universidade Federal do Maranhão, São Luís, MA, Brasil.
Genet Mol Res. 2008 Oct 21;7(4):1089-96. doi: 10.4238/vol7-4gmr483.
A cytogenetic study was carried out in a girl with virilized external genitalia, who showed a karyotype containing a Y isochromosome in mosaic form: mos46,X,iso(Y)(qter-->p11.3::p11.3-->qter)[80]/45,X[17]/46,X,+mar[3]. The chromosome aberrations were confirmed by fluorescence in situ hybridization analysis, with both whole chromosome paint Y probe and centromeric X chromosome probe. The molecular analyses by PCR detected the presence of the SRY, DAZ and AMGY genes, confirming the presence of the whole long arm and almost whole short arm of the Y chromosome. We suggest that the structural alteration of the Y chromosome was a new mutation, which occurred in the initial mitotic divisions of the embryo, originally 46,XY. The breakpoints occurred on the distal extremity of the short arm with later fusion of its extremities producing a Y isochromosome. The later numerical alteration occurred as a consequence of chromosomal instability. Although almost all cells (80%) in peripheral blood belonged to the iso(Y) line with a duplicated SRY gene, this did not determine male sexual differentiation in the patient. The result of accurate evaluation provides correct sex assignment and the prevention of the neoplastic degeneration of a dysgenetic gonad.
对一名外生殖器男性化的女孩进行了细胞遗传学研究，其核型显示含有嵌合形式的Y等臂染色体：mos46,X,iso(Y)(qter→p11.3::p11.3→qter)[80]/45,X[17]/46,X,+mar[3]。通过荧光原位杂交分析，使用全染色体涂染Y探针和着丝粒X染色体探针，证实了染色体畸变。通过聚合酶链反应进行的分子分析检测到SRY、DAZ和AMGY基因的存在，证实了Y染色体的整个长臂和几乎整个短臂的存在。我们认为Y染色体的结构改变是一种新突变；它发生在胚胎最初的有丝分裂过程中，最初为46,XY。断点发生在短臂的远端，随后其末端融合产生一条Y等臂染色体。后来的数目改变是染色体不稳定的结果。虽然外周血中几乎所有细胞（80%）属于具有重复SRY基因的iso(Y)系，但这并没有决定患者的男性性分化。准确评估的结果为正确的性别认定和发育异常性腺的肿瘤性退变预防提供了依据。
