SMN1型
脊髓性肌萎缩
形状记忆合金*
载波测试
遗传学
等位基因
生物
外显子
遗传咨询
遗传连锁
基因检测
基因
产前诊断
组合数学
胎儿
数学
怀孕
作者
Shuji Ogino,Debra G. B. Leonard,Hanna Rennert,Warren J. Ewens,Robert Wilson
出处
期刊:American journal of medical genetics
[Wiley]
日期:2002-06-21
卷期号:110 (4): 301-307
被引量:167
摘要
As evidenced by the complete absence of a functionally critical sequence in exon 7, approximately 94% of individuals with clinically typical spinal muscular atrophy (SMA) lack both copies of the SMN1 gene at 5q13. Hence most carriers have only one copy of SMN1. Combining linkage and dosage analyses for SMN1, we observed unaffected individuals who have two copies of SMN1 on one chromosome 5 and zero copies of SMN1 on the other chromosome 5. By dosage analysis alone, such individuals, as well as carriers of non-deletion disease alleles, are indistinguishable from non-carrier individuals. We report that approximately 7% of unaffected individuals without a family history of SMA have three or four copies of SMN1, implying a higher frequency of chromosomes with two copies of SMN1 than previously reported. We present updated calculations for disease and non-disease allele frequencies and we describe how these frequencies can be used for genetic risk assessment in carrier testing for SMA.
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