Olafsson I, Kristjánsson K, Hjaltadóttir G, Schwartz M, Thornórsson A V
Landspitali University Hospital, Fossvogi, 108 Reykjavík, Iceland.
Laeknabladid. 2000 Mar;86(3):163-6.
Androgen insensitivity syndrome (AIS) is a X-linked rescessive disorder characterized by impairment of the androgen-dependant male sexual differentiation. The cause of AIS is in most cases a mutation in the gene of the androgen receptor on the X chromosome. In this study we describe an Icelandic family with two girls with AIS. A search for mutations in the androgen receptor gene was performed in order to identify the genetical and molecular basis for AIS in this family.
Genomic DNA was isolated from two girls with complete AIS and their close relatives. PCR was used to amplify all eight exons of the androgen receptor gene of the two AIS girls and SSCP used to screen for mutations. DNA fragments showing abnormal SSCP pattern were subjected to nucleotide sequencing. PCR based diagnostic method was developed and used to detect the mutation causing AIS in the family.
Using SSCP and DNA sequencing a CGA to CAA missense mutation in exon 5 at codon 752 was identified. The mutation causes in an Arg to Gln amino acid substitution (R752Q mutation) in the ligand binding domain of the androgen receptor and a complete androgen insensitivity. Members of the family were genotyped using a PCR based method for identification of the mutant allele. The results strongly indicated a de novo mutation in a germ cell of the maternal grandmother, as the mutation was not found in her blood leucocytes. The diagnostic test provided a basis for genetic counselling for the family.
雄激素不敏感综合征（AIS）是一种X连锁隐性疾病，其特征为雄激素依赖的男性性分化受损。在大多数情况下，AIS的病因是X染色体上雄激素受体基因的突变。在本研究中，我们描述了一个有两名患AIS女孩的冰岛家庭。对雄激素受体基因的突变进行了搜索，以确定该家庭中AIS的遗传和分子基础。
从两名患有完全性AIS的女孩及其近亲中分离基因组DNA。采用PCR扩增两名AIS女孩雄激素受体基因的所有8个外显子，并用SSCP筛选突变。对显示异常SSCP模式的DNA片段进行核苷酸测序。开发了基于PCR的诊断方法并用于检测该家族中导致AIS的突变。
通过SSCP和DNA测序，在第5外显子752密码子处鉴定出CGA到CAA的错义突变。该突变导致雄激素受体配体结合域中的精氨酸到谷氨酰胺氨基酸替代（R752Q突变）以及完全的雄激素不敏感。使用基于PCR的方法对家族成员进行基因分型以鉴定突变等位基因。结果强烈表明，该突变是外祖母生殖细胞中的新生突变，因为在她的血液白细胞中未发现该突变。该诊断测试为该家族的遗传咨询提供了依据。
