【Design】狐狸太太日記

A couple from Leicester have been given permission by the fertility watchdog to have a "saviour sibling" in a bid to help their sick 20-month-old daughter. 
Charlotte Mariethoz has the rare blood condition diamond blackfan anaemia and doctors say she needs a stem cell transplant from a genetic match. Her parents will now use IVF to try to have a "designer baby" to save her. In 2004, a British boy with the same disorder was saved by cells from a baby brother born after embryo selection. Michelle and Jayson Whitaker from Chesterfield had Jamie, a saviour sibling for their son Charlie after flying to the US to have the treatment there. Charlotte has already undergone a number of blood transfusions, and is at risk of further complications including a risk of developing a form of leukaemia. Without a transplant she would need further blood transfusions and steroids, her parents Catherine and Charlie have been told by doctors. Mrs Mariethoz said: "This is the first step in the right direction. Obviously there is a long way to go yet. "We hope this decision will now help other families in similar situations."

Genetic match 
The Human Fertility and Embryology Authority (HFEA) has issued a limited number of licences for similar treatments before. But critics say "designing" a child as a tissue donor for a sick sibling undesirable and unnecessary. Tissue testing involves taking one or two cells from an embryo when it is around three days old. If there is a match for the existing child, that embryo will be implanted in the mother's womb so it can develop. Once a baby is born, stem cells are removed from the umbilical cord and stored for four to six months when the transplant to the sick child can take place.

'Devastating' 
Charlotte's condition is not genetic, so there is very little chance any sibling will also be affected. But Dr Simon Fishel, who is treating the Mariethoz family, says using tissue typing will allow a child who is a genetic match for Charlotte to be conceived. "The family have been told that a non-related stem cell transplant is not acceptable, so maybe they should have more babies. "And it would be much more devastating to try naturally and find out they haven't got a match and can't help Charlotte." He said, if the treatment is successful, it would be the first time a saviour sibling would be known to have been conceived and born in the UK. Last year, the parents of six-year-old Zain Hashmi who requires treatment for the blood disorder betathalassaemia major, won permission to seek to create a saviour sibling from the House of Lords, after originally being refused a licence by the HFEA. 


患有可遺傳的視網膜胚細胞瘤的孩子，視網膜出現細胞變異，眼睛的瞳孔即如圖中男童的左眼那樣發白，影響視力。這種眼球癌每一萬五千名兒童就有一人患上，半數病例都源自遺傳。而獲遺傳導致該病的不健全基因的人，有九成機會患上該病。百分之九十五較早驗出的腫瘤都可治愈，但作為治療技術的化療和外科手術，都有致盲的風險。英國一名患上這種癌症的女子近日獲選中開創全國先例，通過移植前遺傳學診斷技術，篩選出沒有導致患上該病基因的試管胚胎懷孕，確保她的孩子不會患上該病。對擔心會把自己所得的病禍延下一代的父母來說，這種受孕技術無疑是一福音。

據《泰晤士報》十三日報道，英國一名女子開創全國先河，懷上經過基因篩選的健康胚胎，將會誕生所謂「設計嬰兒」，以避免下一代也患上母親所患的眼球癌，但這種生育方式引起了很大爭議。 這位準母親的身份未見透露。醫生以基因篩選技術，確保她沒有把自己可遺傳的視網膜胚細胞癌遺傳給孩子。

引起很大爭議

醫生測試這名女子和她丈夫以體外受精方式產生的胚胎，以了解有沒有癌症基因，好讓他們確定只把不受影響的胚胎移植到她的子宮內。相信這名女子的懷孕方式會增加有關「移植前遺傳學診斷」技術的爭議。 有人批評這種篩選生育方式為「不道德」，因為在此過程中可能摧毀可以發育成嬰兒但從來沒有得病的胚胎。而即使潛在可能得病的，出生後多年也都可能是健康的，一些失調是可以治理甚至或者可以預防的。

當局放寬規定 

治理該準母親的醫生瑟哈爾，是英國主要的「移植前遺傳學診斷」技術專家，獲人工授精與胚胎管理局許可，把沒有視網膜胚細胞癌和一種腸癌的基因的胚胎篩選出來，進行生育。人工授精與胚胎管理局剛在本星期初放寬規定，擴大胚胎所患基因遺傳疾病的篩選種類。《泰晤士報》說，以移植前遺傳學診斷技術檢測可遺傳癌症，此前已在美國成功進行。據《泰晤士報》報道，瑟哈爾說：「我們全都很興奮。我們討論的是把這種異常的基因從整個家族世系中去除。其實我們時常做這種事，但每次做都總令人驚奇。」

申請新的篩選 
現在，瑟哈爾的診所正計劃申請，把一名病人沒有BRCA1基因的胚胎篩選出來。這種基因能令其攜帶者患乳癌的終生風險增至八成。 嬰兒出生頭一年所患的所有癌症中，百分之十一是視網膜胚細胞癌。近半數個案都由RB1基因遺傳變種引起。父母有這種不健全基因，會有五成機會把它遺傳給孩子，而受遺傳者有九成機會將來會患腫瘤。而變種亦把患上其他癌症的終生風險由三分之一增至超過一半。