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视网膜母细胞瘤(RB)是一种幼儿的恶性视网膜肿瘤,约4%的患者携带一条13号同源染色体长臂缺失。他们都有13q14部分或全部缺失,表明此部位的基因与RB的发生有关。在无此种缺失的病例中,25～40%有高外显率的RB按孟德尔常染色体显性规律遗传。酯酶D(EsD)基因已定位于13q14区,并与遗传型RB基因连锁。每个携带13q14缺失的杂合子患者,显示其EsD酶活性为正常个体的50%。缺失较大的患者几乎都合并有智力活动迟缓,而缺失较小的患者除发生RB外,表型是正常的。EsD酶分析已成功地用于识别表型正
Retinoblastoma (RB) is a malignant retinal neoplasm in young children. About 4% carry a long arm deletion of homologue 13. They all have 13q14 partial or complete deletion, indicating that the gene in this locus is related to the occurrence of RB. In the absence of such deletions, 25-40% of RBs with high penetrance are inherited by Mendelian autosomal dominant patterns. Esterase D (EsD) gene has been located in the 13q14 region, and with genetic RB gene linked. Each heterozygous patient carrying a 13q14 deletion showed an EsD enzyme activity of 50% of that of a normal individual. Almost all patients with large deletions had mental retardation, whereas patients with smaller defects had a normal phenotype other than RB. EsD enzyme assays have been used successfully to identify phenotypic positives