- 期刊
Prenatal Genetic Counseling on a Woman with Advanced Maternal Age and a Family History of a Known Genetic Disease
對有家族性遺傳病之高齡產婦的產前遺傳諮詢
摘要
例行的遺傳病帶因者分析及產前診斷方法是：若家族內特定的突變基因型屬已知，則直接對該突變基因進行分析；若突變基因型不明，則以間接方式的連鎖分析法行之。另一比較費勁的方法是從整個致病基因序列裡一一去找出突變的位置。本文報導一個產前診斷的特殊案例。來就診的病人是一位高齡產婦，已知家中有一位小孩患了囊胞性纖維瘤(Cystic fibrosis)，但產前染色體檢查結果，卻意外發現懷了患唐氏症(Down Syndrom)的胎兒。該患囊胞性纖維瘤的小孩原先只知帶了△F508 及另一不明來源的突變對偶基因，但經一再努力分析之後才確定係罕見的 Q207X；也因此，預防性的產前診斷工作變成可行。惟沒想到，染色體產前檢查竟會發現胎兒患有唐氏症。雖然分子檢查結果顯示是個完全不帶△F508或Q207X突變的正常胎兒，該病人夫婦因受太大打擊即行墮胎。儘管囊胞性纖維瘤在台灣屬罕見疾病，本案例提醒遺傳諮詢員一個重要的課題：在提供產前遺傳諮詢服務時，必要告知產婦懷孕前後可能遭遇的全面狀況。
並列摘要
Carrier and prenatal diagnosis for families with known genetic disease are usually carried out by direct mutational analysis of the diseased gene if the mutations are known, or by an indirect method such as linkage analysis if the mutation is not identified. An alternative is the direct DNA sequencing of the entire diseases gene for mutations. Here we report a prenatal diagnosis of a woman with advanced maternal age who had an affected child with cystic fibrosis (CF) and unexpectedly revealed a fetus with trisomy 21 in the current pregnancy. The affected child was compound heterozygous for △F508 and an unidentified CF allele in the initial diagnosis. After much effort had been made to identify the unknown mutant allele and to find informative markers for linkage analysis, a rare mutation, Q207X, was eventually identified and a definitive diagnosis of CF for the subsequent pregnancy was possible. Unfortunately, the cytogenetic finding of a fetus with aneuploidy was so emotionally devastating that the pregnancy was terminated despite the absence of CF mutations. Although the occurrence of CF in Taiwan is rare, this case emphasizes the importance of thorough consideration of all factors that may affect pregnancy outcome during prenatal genetic counseling.