NZ HD Diagnosis,

Family Planning & Prenatal Diagnosis

local Huntington's Disease Association which is the only source of support, information and to find out about the services available.

2 For those "at risk" who wish to go through the Predictive Test program must comply with the local protocol to ensure that the needed information and support is available for this devastating 'test' which most agree enables one's family to be positive and make the most of life at all times.

3 To find out how families were coping with having the results of the Predictive Test, the Association in Wellington arranged for Alison Gray, interviewer and editor of "Genes & Generations, Living With Huntington's Disease" to research into Family Responses to Predictive Testing among those who had been tested by the Central Regional Genetics Service.

4 Those coping with behavioral problems arising from Huntington’s Disease will appreciate the advice given by Professor Pete Ellis, of the Department of Psychological Medicine at the Wellington School of Medicine, to the Wellington HD Conference, September 1997.

5 Family Planning & Prenatal Diagnosis

Until recently an individual who is at risk of, or has HD and wishes to have a baby who will not inherit the condition, could opt to have a test during their pregnancy. This form of testing is called prenatal testing which is explained fully on the Canadian site.

In the British Huntington’s Disease Association Summer 98 Newsletter an article by Alison Lashwood, Genetic counselor at Guys Hospital, London, outlines a new form of prenatal testing which is being developed which should avoid the need for termination of a pregnancy inheriting the HD gene. This form of testing is called preimplantation diagnosis.

Preimplantation Diagnosis (PIGD) involves the creation of an embryo using "test tube" baby techniques (usually used for couples who have problems with infertility). A sperm from the male is used to fertilize an egg from the female invitro (IVF) (i.e. in a test tube). At a very early stage of embryo development, one or two cells are removed and analyzed for the presence or absence of the HD mutation. Only the embryos (a maximum of three) which do not have the HD mutation are then replaced in the female partner where it is hoped that these will lead to a successful pregnancy. There appears to be no evidence yet to suggest that removing a few cells at this early stage in embryo development causes any harm to a baby.

Difficulties with preimplantation diagnosis

It is important to stress that this form of testing is very much in its infancy. Although around 100 children have been born worldwide following PIGD for a variety of genetic conditions, there are no confirmed reports of a successful PIGD for HD yet.

The treatment used for couples wanting PIGD is similar to those undergoing IVF treatment. The pregnancy success rate for this treatment is about 1 live born baby in every 5 IVF cycles performed.

Funding for PIGD is similar to the way funding for IVF treatment is organized. Some local health authorities will pay for treatment, others will not fund it. This means that sadly many couples considering PIGD will have to raise some, if not all the cost themselves.

What is currently available for individuals/couples interested in PIGD for HD?

At present we do have a number of people at risk of HD who are on our waiting list for PGID. Some individuals have themselves had a positive predictive test. We would hope to be able to offer direct mutation screening in the embryos of these couples.

Direct mutation screening means that we can look for the gene change (mutation) that causes HD and we do not need blood samples from other family members.

We have also received requests from individuals who are at 25% risk of HD and have requested that their embryos are tested with no information given that might indicate whether the parent has HD gene or not. We call this PIGD by non-disclosure.

We may be able to test embryos of individuals requesting this by using "linkage analysis".

However this is not something that we will be able to do by direct mutation screening as we feel that it may be difficult to ensure that information about the HD nutation status of the embryos is not divulged inadvertently.

What do I do if I am interested in PIGD?

We are happy to receive referrals via other Genetic Centres throughout the UK. Therefore you would first need to contact your local geneticist to discuss your request. After receiving a referral, an interested couple will be written to by the PIGD team co-ordinator with details of what is involved in the process. Those who are still interested can then arrange an appointment which will be in London at St Thomas’ Hospital. At this point further details will be discussed regarding when testing may be possible and the limitations of PIGD.

Our PIGD program at Guy’s and St Thomas’ Hospital is one of several now licensed to practice in the UK. For details of other centres offering PIGD you should contact your local Genetics Centre.

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Let us hope that we have these services in NZ soon. Do discuss them with your regional Clinical Geneticist well before the beginning of your pregnancy. Today there is more information and options, which are becoming more readily available to enable families to have children without the gene.

Our Huntington’s Disease professionals, scattered throughout NZ can be contacted for any questions about any aspect of Huntington’s Disease.

Auckland

Dr Ingrid Winship                                          Beth Gorden- Feild Oficer
Clinical Geneticist                                         P.O. Box 91-489
Department Molecular Medicine                     Auckland Mail Service Centre
School of Medicine                                       Auckland
University of Auckland                                  Ph (09)4802 336 (Home)
Private Bag 92019                                        025 749 163
Auckland                                                     Fax (09) 4803 025
Phone(09) 3737 599 ext 6373
or (09) 6309 802
025 810 737

Jennie Giles & Dale Gilbert                         Dr Lynette Tippet
Genectic Services                                      Nueropsychologist
7th Floor                                                    Department of Psychology
Star Ship Hospital                                      University of Auckland
Auckland                                                   Private Bag 92 019
Pn (09) 6309 802                                        Auckland
Fax (09) 3074 978                                       Ph (09) 3737 599ext 8551 (work)
                                                                (09)4864 288 (home)

Wellington

Dr Joanne Dixon                                  Dorothy Dortell
Clinical Geneticist                                Social Worker
Wellington Hospital                              HDA (Wellington)
Private Bag 7902                                 Social Work Department
Wellington South                                 Wellington Hospital
Ph (04) 4855 999                                 Private Bag 7902
                                                         Wellington South
                                                         Ph (04) 3855 850
                                                         Fax 3844 022      

Christchurch

Caroline Lintott                                     Jaccy Creak
Genetic Associate                                Feild Officer
Lipid & Diabetes Research Group         HDA (Christchurch )
Hagley                                                 PO Box 13 018
Christchurch Hospital                            Armagh
Private Bag                                          Christchurch
Christchurch                                         Ph (03) 365 9409
Ph (03) 364 0449   
(03) 364 1092  (direct line)