11个Fabry病家系的α-半乳糖苷酶A活性及GLA基因检测

目的 建立Fabry病α-半乳糖苷酶A（α-gal A）酶活性及基因检测体系,并对基因型临床表型进行分析。方法 检测11个Fabry病家系先证者及家系成员外周血粒细胞α-gal A活性及GLA基因。酶活性检测采用底物荧光法,基因检测采用PCR直接测序法,并进行临床评估。结果 在11个Fabry病家系中检出9种GAL基因突变,包括5个错义突变（R301Q、I91T、G132R、F273L、D165Y）,2个无义突变（W236X、R342X）,1个单碱基缺失（1082delG）和1个大片段缺失（44 bp nt．1077）,其中4种为新突变（D165Y、F273L、1082delG、44 bp nt．1077）。11个家系中通过基因及酶活性检测,确诊男性半合子13例,女性杂合子12例。男性半合子α-gal A酶活性显著下降,女性杂合子α-gal A酶活性部分下降,1/4女性杂合子的α-gal A酶活性处于正常范围内。结论 确诊了11个Fabry病家系的GLA基因突变类型,并筛出所有家系中先证者以外的患者14例。外周血粒细胞α-gal A酶活性和GAL基因检测是筛查和诊断Fabry病的有效手段。

Study of alpha-galactosidase A activity detection and gene survey in 11 Chinese pedigrees with Fabry disease

Objective To investigate the alpha-galactosidase A activity and the mutations of GLA gene in Chinese pedigrees with Fabry disease. Methods All 7 exons and their neighboring intronic sequences of the GLA gene of the probands were analyzed by PCR and direct sequencing. The α-gal A enzymatic activity in peripheral leukocytes was measured by fluorogenic substrate, 4-methylumbelliferyl-a-D-galactopyranoside. Mutation screening in the pedigrees of the probands was also performed. Results Nine mutations including 4 novel mutations was identified in 11 probands. The mutations comprised of missense mutations (R301Q, I91T, G132R, F273L, D165Y), nonsense mutations (R342X, W236X), as well as a single nucleotide deletion (1082delG) and a gross deletion (44 bp nt. cd 1077). Forteen carriers of the relevant mutations including 3 hemizygotes and 11 heterozygotes in the pedigrees and less than 50% probands offered a positive family history at the beginning of the study. All the hemizygotes showed low enzymatic activity (<1 nmol•hr－1•mg－1) but 1/4 of heterozygotes had the enzymatic activity within normal range. Conclusions Nine mutations including 4 novel mutations in 11 Chinese pedigrees with Fabry disease are identified by PCR-DNA sequencing. Gene analysis and enzymatic activity detection should be performed to improve the identification of the disease. Identification of new mutations in this disease and mutation screening in the pedigrees will be helpful to the genetic counselling and proper treatment.