Braun A, Kammerer S, Cleve H, Löhrs U, Schwarz H P, Kuhnle U
Institute of Anthropology and Human Genetics, Children's Hospital, University of Munich, Germany.
Am J Hum Genet. 1993 Mar;52(3):578-85.
Recently, the gene for the determination of maleness has been identified in the sex-determining region on the short arm of the Y chromosome (SRY) between the Y-chromosomal pseudoautosomal boundary (PABY) and the ZFY gene locus. Experiments with transgenic mice confirmed that SRY is a part of the testis-determining factor (TDF). We describe a sporadic case of a patient with intersexual genitalia and the histological finding of ovotestes in the gonad, which resembles the mixed type of gonadal tissue without primordial follicle structures. The karyotype of the patient was 46,XY. By PCR amplification, we tested for the presence of PABY, SRY, and ZFY by using DNA isolated from peripheral blood leukocytes and for the presence of SRY by using DNA obtained from histological gonadal slices. The SRY products of both DNA preparations were further analyzed by direct sequencing. All three parts of the sex-determining region of the Y chromosome could be amplified from leukocytic DNA. The patient's and the father's SRY sequences were identical with the published sequence. In the SRY PCR product of gonadal DNA, the wild-type and two point mutations were present in the patient's sequence, simulating a heterozygous state of a Y-chromosomal gene: one of the mutations was silent, while the other encoded for a nonconservative amino acid substitution from leucine to histidine. Subcloning procedures showed that the two point mutations always occurred together. The origin of the patient's intersexuality is a postzygotic mutation of the SRY occurring in part of the gonadal tissue. This event caused the loss of the testis-determining function in affected cells.
最近，已在Y染色体短臂上的性别决定区域（SRY）中，介于Y染色体假常染色体边界（PABY）和ZFY基因座之间，鉴定出了决定男性性别的基因。转基因小鼠实验证实，SRY是睾丸决定因子（TDF）的一部分。我们描述了一例散发性病例，患者生殖器两性畸形，性腺组织学检查发现为卵睾，类似于无原始卵泡结构的混合型性腺组织。患者的核型为46,XY。通过PCR扩增，我们使用从外周血白细胞中分离的DNA检测PABY、SRY和ZFY的存在，并使用从性腺组织切片获得的DNA检测SRY的存在。对两种DNA制备物的SRY产物进行直接测序进一步分析。Y染色体性别决定区域的所有三个部分均可从白细胞DNA中扩增出来。患者和父亲的SRY序列与已发表序列相同。在性腺DNA的SRY PCR产物中，患者序列中存在野生型和两个点突变，模拟了Y染色体基因的杂合状态：其中一个突变是沉默的，另一个编码从亮氨酸到组氨酸的非保守氨基酸替换。亚克隆程序表明，这两个点突变总是同时出现。患者两性畸形的起源是性腺组织部分发生的SRY合子后突变。这一事件导致受影响细胞中睾丸决定功能丧失。
