By a “cruel stroke of genetic fate”, the Allen family turn out to be affected by not just for one, but two horrendous genetic diseases. This programme, the second in the Bitter Inheritance series on genetic disease, begins by telling the story of Bethany, a young girl who was born with Sanfilippo syndrome. (Further information about this disease can be found at this BBC website). This is a rare autosomal recessive disorder, i.e. you need to inherit a faulty copy of the relevant gene from both parents. The disease causes the progressive degeneration of both the nervous system, including the brain, and will ultimately lead to Bethany’s death, probably during her mid-teens. With no cure available, the family frequently express their feeling of helplessness and frustration. As John, her father, states “when you are told that your daughter is going to die… you can’t imagine it”. The family is provided with much support by friends and doctors who reassure the parents that she is happy and that “she’ll never know she has got it, and she’ll never be in any pain”.
After much deliberation, Bethany’s parents (00:04:24) decide they want to try and have another child. Without any sort of medical intervention, there is a 1-in-4 possibility that the new child will also have the syndrome. This raises a clear ethical question – knowing those odds, should the parents continue? If they do take that risk, are they prepared to abort an affected foetus? As it turns out, the new child is not a sufferer, but clips show the emotional rollercoaster taken by both parents along the way and the difficult decisions the have to make (00:19:50 to 00:20:32 and 00:30:19 to 00:38:20).
Whilst all of this is going on, it turns out that Bethany’s grandmother has Huntington’s disease (HD). Like Sanfilippo Syndrome, HD is a progressive neurodegenerative disease, but it differs both in the way it is inherited (in an autosomal dominant fashion, i.e. if you’ve got one copy of the gene, then you will get the disease) and at the time of onset (a sufferer normally starts to show symptoms in their 40s rather than aged 2 to 4). A section halfway through the episode (00:23:05 to 00:28:17) shows the burden on the already emotionally-strained family; as Jo, Bethany’s mother, puts it “If you think about it too much, you would crack up”. Jo’s sister summarises the nightmare scenario which might unfold over the next ten years: “For Jo, she could have a mother that’s ill [with HD], a daughter who’s sick [with Sanfilippo], a sister who is seriously ill [with HD] and find that she is also seriously ill [with HD]”.
As in the previous episode on the Gorry Family, the issue of who should be tested crops up. This is particularly controversial for late-onset diseases such as HD, because it is feasible for a younger family member to be tested before the condition before the person they believe may have passed it to them has shown any symptoms. If the younger person tests positive, the older relative is guaranteed to get the disease but may not have wished to know their own genetic status. Note that the fifth episode of Bitter Inheritance, focussing on the Day Family, revisits Huntington’s disease, and the issues of whether or not to be tested, in more detail.
As with other episodes in this series, this 40 minute programme has only been transmitted twice: 17th January 2002 (BBC2; 21:50) and 9th June 2003 (BBC2; 23:20). Copies can be obtained from the BUFVC, TRILT identifier 001685A8).