Huntington's disease: a clinical review

Huntington disease (HD) is a rare neurodegenerative disorder of the central nervous system characterized by unwanted choreatic movements, behavioral and psychiatric disturbances and dementia. Prevalence in the Caucasian population is estimated at 1/10,000-1/20,000. Mean age at onset of symptoms is 30-50 years. In some cases symptoms start before the age of 20 years with behavior disturbances and learning difficulties at school (Juvenile Huntington's disease; JHD). The classic sign is chorea that gradually spreads to all muscles. All psychomotor processes become severely retarded. Patients experience psychiatric symptoms and cognitive decline. HD is an autosomal dominant inherited disease caused by an elongated CAG repeat (36 repeats or more) on the short arm of chromosome 4p16.3 in the Huntingtine gene. The longer the CAG repeat, the earlier the onset of disease. In cases of JHD the repeat often exceeds 55. Diagnosis is based on clinical symptoms and signs in an individual with a parent with proven HD, and is confirmed by DNA determination. Pre-manifest diagnosis should only be performed by multidisciplinary teams in healthy at-risk adult individuals who want to know whether they carry the mutation or not. Differential diagnoses include other causes of chorea including general internal disorders or iatrogenic disorders. Phenocopies (clinically diagnosed cases of HD without the genetic mutation) are observed. Prenatal diagnosis is possible by chorionic villus sampling or amniocentesis. Preimplantation diagnosis with in vitro fertilization is offered in several countries. There is no cure. Management should be multidisciplinary and is based on treating symptoms with a view to improving quality of life. Chorea is treated with dopamine receptor blocking or depleting agents. Medication and non-medical care for depression and aggressive behavior may be required. The progression of the disease leads to a complete dependency in daily life, which results in patients requiring full-time care, and finally death. The most common cause of death is pneumonia, followed by suicide

Decreasing uptake of predictive testing for Huntington's disease in a German centre: 12 years' experience (1993–2004)

In this retrospective study, we examined changes in decision-making for and against the predictive genetic test for Huntington's disease including 478 persons at risk who had undergone genetic counselling in one centre in Germany between 1993 and 2004. At the outset of the counselling procedure the majority of subjects (71%) wanted to make use of the test, yet the actual demand of the predictive test result declined from 67 to 38% over the years. In addition, the time interval between counselling session and blood withdrawal was reduced, as determined by the counselees: in 2000–2004 the majority of persons at risk made the appointment for blood withdrawal after the shortest possible time span. Demographic factors of the cohort remained comparatively stable in the investigated time period. An association was evident between the ratio of test usage and the counselling person. These and other possible factors influencing the time flow of predictive DNA testing are discussed. Further studies are necessary to investigate whether changes of test demand rates are a general phenomenon

Quality issues concerning genetic counselling for presymptomatic testing: a European Delphi study.

Genetic counselling for presymptomatic testing is complex, bringing both ethical and practical questions. There are protocols for counselling but a scarcity of literature regarding quality assessment of such counselling practice. Generic quality assessment tools for genetic services are not specific to presymptomatic testing (PST). Therefore, the aim of this study was to identify aspects of effective counselling practice in PST for late-onset neurological disorders. We used the Delphi method to ascertain the views of relevant European experts in genetic counselling practice, ascertained via published literature and nomination by practitioners. Ethical approval was obtained. Questionnaires were sent electronically to a list of 45 experts, (Medical Doctors, Geneticists, Genetic Counsellors and Genetic Nurses), who each contributed to one to three rounds. In the first round, we provided a list of relevant indicators of quality of practice from a literature review. Experts were requested to evaluate topics in four domains: (a) professional standards; (b) service standards; (c) the consultant's perspective; and (d) protocol standards. We then removed items receiving less than 65% approval and added new issues suggested by experts. The second round was performed for the refinement of issues and the last round was aimed at achieving final consensus on high-standard indicators of quality, for inclusion in the assessment tool. The most relevant indicators were related to (1) consultant-centred practice and (2) advanced counselling and interpersonal skills of professionals. Defined high-standard indicators can be used for the development of a new tool for quality assessment of PST counselling practice