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PubMed1998

Predictive testing for Huntington's disease: ten years' experience in two Italian centres.

Pre-symptomatic testing for Huntington's disease (HD) has been available as a clinical service in the medical centres of Rome and Genoa since December 1987, initially by DNA-linkage and since mid-1993 by direct mutation analysis. A multidisciplinary approach and a protocol which follows the Ethical Issue Policy Statement on Huntington's Disease Molecular Genetics Predictive Test has been used. In the period under study, 332 subjects requested the test, 288 were enrolled in the protocol and nearly half of these completed it. One hundred and forty-eight people withdrew from the testing procedure for various reasons but most frequently due to a more realistic evaluation of all possible consequences of test results, induced by psychological counselling. Therefore, 140 people completed the test. The overall gene-carrier/non-carrier ratio was 0.46:1. None of the identified gene carriers had catastrophic reactions such as suicide, suicide attempts or major psychiatric disorders. All appear to have had a similar pattern of reactions to an adverse result and none expressed regret for undergoing the test. In conclusion, presymptomatic testing for HD can be considered a safe procedure without adverse consequences when framed in an integrated protocol at qualified genetic centres.

Adaptation, Psychological↗
PubMedDate not supplied

Emotional reactions to predictive testing in Alzheimer's disease and other inherited dementias.

This work describes the reasons and emotional responses of healthy descendants after counseling for presenilin mutations in early-onset familial Alzheimer's disease (EOFAD), tau mutations in familial frontotemporal dementia (FTD), and prion mutations in fatal familial insomnia (FFI). A multidisciplinary protocol following Huntington's disease counseling guidelines and a post-test follow-up program were developed to counsel healthy descendants of affected families. The psychological consequences, anxiety levels, and depression status were assessed through validated scales before and after disclosing the information. Nine people from three different families, one with EOFAD, another with FTD, and the other with FFI came for counseling. Their main reason for testing was to initiate early treatment in the future. Disclosing the information decreased anxiety in two carriers, increased it temporarily in one, and had no effect in another. All noncarriers felt relieved. Overall, after a mean of 30 months of follow-up, no negative psychological reactions were observed. All participants positively valued the program. Although preliminary, our observations suggest that predictive testing in EOFAD, FTD, and FFI is safe and may be of benefit when performed with a delicate approach under strict pretest counseling protocols and post-test follow-up programs. The emotional reactions were similar, although the diseases, their phenotype, and mutation characteristics were different.

Adult↗
PubMed2004

Sensitivity to carbon dioxide in subjects with a single lifetime panic attack: possible clinical "bedside" predictive test for panic disorder after a first attack.

There is currently no way of knowing whether a patient who has recently had a single panic attack has incipient panic disorder. Sensitivity to carbon dioxide (CO2) is lower in healthy volunteers than in panic disorder patients. If this is also true of people who experience a single lifetime panic attack, it could be used as a prognostic test. Subjects with a single lifetime panic attack and subjects with panic disorder received an inhalation of 35% CO2. Subjects completed the panic symptoms scale (PSS), and also stated whether they considered that they had experienced an attack. None of 14 subjects with a single lifetime panic attack, compared to 7 of 17 subjects with panic disorder (P=.009), had an attack. The PSS also distinguished between the groups. The 35% CO2 challenge warrants further investigation as a predictive test after a first panic attack.

Administration, Inhalation↗
PubMed2005

[Predictive testing: presymptomatic diagnosis in neurogenetic disorders].

Presymptomatic testing is available since 15 years for Huntington disease and it is now possible for a number of other neurogenetic disorders, mostly neurodegenerative disorders. The possibility of determining the genetic status of an at-risk person for the disorder which run in his family raises questions because of the absence of preventive and curative treatments in most instances. In addition, being carrier does not tell you when the disease will start and how it will evolve, impairing the possibilities of planning the future. A pluridisciplinary approach to predictive testing with care before, during and after the test taking into account the medical, social and psychological aspects of the disease is good practice. At the present time, only a minority of at-risk individuals request presymptomatic testing and almost 50 % do not pursue until the results. The consequences of the test may be harmful, more frequently after an unfavorable than after a favorable result. Although the motivations and the outcome in terms of request for prenatal testing after a carrier result are different in Huntington's disease and spinocerebellar ataxias, our experience underlines the benefit of pluridisciplinary care and of time for decision taking. For other disorders like familial Alzheimer's disease, or familial Creutzfeldt-Jakob disease, the experience in presymptomatic testing is still limited but the situation seems similar to Huntington's disease because of the presence of dementia. It will be interesting to study the motivations and the outcome of the tests in disorders like autosomal dominant spastic paraplegias which usually do not reduce the life expectancy. Nevertheless, the overall situation might change greatly when efficient treatments will become available in these disorders.

Adult↗
PubMed1989

Aspects of the immune response to contact allergens: opportunities for the development and modification of predictive test methods.

A variety of guinea-pig tests are currently employed to assess the skin-sensitizing potential of chemicals. Although some such tests, in particular the guinea-pig maximization test and the occluded patch test of Buehler, have become well established, widely applied and are of proven value in the safety evaluation of chemicals, they have certain limitations. It is the purpose of this review to examine various aspects of the immune response to contact allergens and the way in which an understanding of the molecular and cellular events that characterize the induction and elicitation of contact sensitivity may be applied to the development and modification of predictive test methods. Attention is focused on the role of dendritic cell migration and T lymphocyte activation during the induction phase of skin allergy and the association of acute-phase proteins and vasoactive amines with the elicitation reaction.

Allergens↗
PubMed1993

Diagnosis of Huntington disease: a model for the stages of psychological response based on experience of a predictive testing program.

Persons diagnosed as affected with Huntington's disease (HD) may have similar stages of psychological response to the clinical presentation of the illness. Here we describe a model of these stages of response based on our experience during a predictive testing program for HD. During the Warning Stage, asymptomatic persons are aware of their risk status for HD and develop defenses which favor adaptation to their genetic risk. In response to the initial signs and symptoms of HD (the Incipient Stage) unconscious working through of this realization occurs while it is still kept out of conscious awareness. When symptoms become obvious such that recognition of disease onset is inevitable (Breakthrough Stage) the possibility of the diagnosis of HD is assimilated. After the delivery of the diagnosis during the Adjustment Stage, short- and long-term adaptive responses to living with HD occur. Recognition of the stage of psychological response of a patient who presents with HD is important prior to delivering a clinical diagnosis. In a significant minority of cases, the psychological readiness lags behind the clinical symptomatology and premature presentation of a diagnosis may result in significant untoward adverse events. Understanding of the stages of response may provide a framework for evaluating the psychological state of the person with HD and determining their readiness to receiving the diagnosis. This model may have relevance to the psychological responses of patients to the diagnosis of other late onset autosomal dominant disorders.

Adaptation, Psychological↗
PubMed1999

Fenfluramine challenge test predicts outcome in pharmacological treatment of patients with functional gastrointestinal disorder.

We investigated if response to the fenfluramine challenge test could predict outcome in 47 nonpsychiatric patients with chronic functional gastrointestinal disorder (FGD) treated with mianserin, a drug closely related to mirtazepine, or placebo. Sixty milligrams of fenfluramine was given orally in the morning on nonfasting basis. Serum cortisol (COR) and prolactin (PRL) were analyzed at baseline, and after 120, 180, and 240 minutes. Patients were then randomized into a 7-week double-blind treatment trial with mianserin or placebo. Response to treatment with mianserin (76% vs.18% for placebo) was closely linked to a high increase in PRL and COR following a fenfluramine challenge test (positive predictive power=72%). Adding length of illness history increased both positive and negative predictive power to 92%. Our results indicate that the fenfluramine challenge test may be a potentially useful tool to identify nonpsychiatric subjects with FGD, who will most likely respond to treatment with a combined alpha2 and 5HT-2 and -3 antagonist.

Adult↗
PubMedDate not supplied

Can the impingement test predict outcome after arthroscopic subacromial decompression?

The impingement test, placement of local anesthetic in the subacromial space, is considered a useful tool in diagnosing impingement syndrome. The purpose of this study was to examine the predictive value of the impingement test with respect to outcome after arthroscopic subacromial decompression. Fifty-five patients who had a preoperative impingement test were evaluated at 3 and 12 months postoperatively. We noted 88% satisfactory results in patients in whom the impingement test was positive, with only 63% satisfactory results at 3 months and 60% satisfactory results at 12 months in patients in whom the impingement test was negative. Although workers' compensation patients tended to have lower scores than others, the impingement test result was more predictive of outcome than was compensation status. Impingement test results and preoperative American Shoulder and Elbow Surgeons scores were independent predictors of postoperative American Shoulder and Elbow Surgeons scores. Our evidence indicates that the impingement test can be used as a predictor of outcome for patients with impingement syndrome treated by arthroscopic subacromial decompression.

Adult↗
PubMed1987

A predictive test for Huntington's disease: recombinant DNA technology and implications for nursing.

A genetic marker for Huntington's disease has been located through the use of new recombinant deoxyribonucleic acid (DNA) technology. As a result, researchers can now identify presymptomatic individuals who will develop this disease. Recently, the same approach used to locate the Huntington's disease marker led to the discovery of gene markers for Alzheimer's disease and manic-depressive illness. It is likely that clinical tests for this and other neurogenetic diseases will soon become available. The ability to perform presymptomatic and prenatal testing on individuals at risk for genetic diseases raises difficult ethical, social, and psychological issues. It is imperative that nurses understand the technology involved and be prepared to help clients cope with the profound effects genetic testing will have on their lives. Using the example of the discovery of the genetic marker for Huntington's disease, this article examines one aspect of current recombinant DNA technology, discusses the major issues raised by the availability of a predictive test, and looks at implications for nursing care.

DNA, Recombinant↗
PubMed1982

Ethics of a predictive test for Huntington's chorea.

"Index Medicus" and 18 other publications have been consulted in an attempt to provide an easily assimilated selection of the recently published and widely dispersed material relevant to the ethical debate the editors of the "BMJ" called for on 4 March 1978. The medical profession is shown to be deeply divided on the ethics of a predictive test for Huntington's chorea. Some members are already using the prospect of a reliable test as an inducement to potential transmitters of this incurable hereditary disease to postpone procreation. Other members would prefer to see any future test withheld from every applicant until such time as radically improved means of treatment or a cure is discovered. The evolution of generally acceptable professional guidelines requires further informed debate.

Adult↗
PubMed1999

TaqMan PCR-based gene dosage assay for predictive testing in individuals from a cancer family with INK4 locus haploinsufficiency.

BACKGROUND: A genetic syndrome of cutaneous malignant melanoma and nervous system tumors recently has been characterized and shown to be linked to the INK4 locus in the 9p21 region. Hemizygosity at adjacent physically mapped microsatellite markers indicated deletion of p16, p19, and p15 clustered tumor suppressors. Because individuals from this family could benefit from predictive testing in terms of cancer prevention, we developed a direct test without need to analyze parental DNAs to comply with the rules of individual consent and secrecy. METHODS: We developed an assay using TaqManTM real-time quantitative PCR, with p15 as the test sequence and albumin (ALB) as the reference gene. The normalized ratio of p15/ALB is expected to yield a value of approximately 1 in individuals without the deletion, whereas a ratio of approximately 0.5, indicating p15 haploinsufficiency, is expected in predisposed individuals. RESULTS: All patients harboring the previously defined at-risk haplotype were correctly identified using this approach. In six individuals with deletions, the p15/ALB ratios were 0.472-0.556 (SD, 0.013-0.078). In the five individuals without deletions, the ratios were 0.919-1.019 (SD, 0.006-0.075). CONCLUSIONS: This is the first report of a high-throughput, automatable gene dosage assay successfully applied to the identification of a germ-line deletion. This approach, not limited by marker informativeness or the need for harvesting live cells, can be applied to any condition with haploinsufficiency and extended to the characterization of most abnormalities of the ploidy.

Carrier Proteins↗
PubMed2001

Predictive genetic testing in children.

Predictive genetic testing should only be performed on children if it is in their best interests. "Interests" include psychosocial elements. Predictive testing is performed on children when there are interventions to prevent disease or to detect and treat it early and it is necessary to begin these interventions in childhood. It is also performed for diseases known to commence in childhood. Predictive testing in children for adult-onset conditions for which there is no medical intervention is highly controversial. Competent children and adolescents can consent to predictive genetic testing. Predictive testing can result in harm, such as discrimination (eg, in insurance entitlement or employment) and stigmatisation. Predictive testing can have important non-medical benefits in terms of self-knowledge and life planning.

Australia↗
PubMed1990

Partners of Huntington patients: implications of the disease and opinions about predictive testing and prenatal diagnosis.

Huntington's disease imposes a considerable burden on the patient and also on the family, especially on the partner. The present paper is based on a survey about the consequences of the disease from the point of view of the partner of the Huntington patient. The mental deterioration and the personality changes seem to be the most difficult aspects to cope with. The threat that their own children may later on develop the same disease is one of the most dramatic aspects. Most partners were aware of the availability of predictive testing for Huntington's disease and were concerned about the far-reaching consequences of the test result. There was a relatively high consensus that the test should only be delivered within a counseling context. Three out of four respondents were in favour of the availability of prenatal diagnosis for Huntington's disease.

Adaptation, Psychological↗
PubMed2004

Testing predictions of the double-strand break repair model relating to crossing over in Mammalian cells.

In yeast, four-stranded, biparental "joint molecules" containing a pair of Holliday junctions are demonstrated intermediates in the repair of meiotic double-strand breaks (DSBs). Genetic and physical evidence suggests that when joint molecules are resolved by the cutting of each of the two Holliday junctions, crossover products result at least most of the time. The double-strand break repair (DSBR) model is currently accepted as a paradigm for acts of DSB repair that lead to crossing over. In this study, a well-defined mammalian gene-targeting assay was used to test predictions that the DSBR model makes about the frequency and position of hDNA in recombinants generated by crossing over. The DSBR model predicts that hDNA will frequently form on opposite sides of the DSB in the two homologous sequences undergoing recombination [half conversion (HC); 5:3, 5:3 segregation]. By examining the segregation patterns of poorly repairable small palindrome genetic markers, we show that this configuration of hDNA is rare. Instead, in a large number of recombinants, full conversion (FC) events in the direction of the unbroken chromosomal sequence (6:2 segregation) were observed on one side of the DSB. A conspicuous fraction of the unidirectional FC events was associated with normal 4:4 marker segregation on the other side of the DSB. In addition, a large number of recombinants displayed evidence of hDNA formation. In several, hDNA was symmetrical on one side of the DSB, suggesting that the two homologous regions undergoing recombination swapped single strands of the same polarity. These data are considered within the context of modified versions of the DSBR model.

Animals↗
PubMed1997

A BRCA1 founder mutation, identified with haplotype analysis, allowing genotype/phenotype determination and predictive testing.

We searched for a founder mutation in a population from one geographic region of Norway with prevalent breast/ovarian cancer families. We sampled 33 breast/ovarian cancer families and determined haplotypes of four markers linked to the BRCA1 region. Of the affected 33 index women, 13 (39.4%) shared one haplotype. In five (15% of total), an identical mutation was indicated by an abnormal truncated protein test (PTT) of exon 11 and shown to represent a 1675delA mutation. In the other index women, PTT of exon 11 showed no abnormality. No other BRCA1 founder mutation of this prevalence is likely because no other haplotype was more frequent in affecteds than in controls. All families with the 1675delA mutation in this geographic region may be considered as part of one large kindred. This allows a genotype-phenotype correlation to be precisely determined and used in genetic counselling for predictive testing within this kindred. Identification of identical haplotypes between unrelated affected individuals may be used to estimate the extent of founder effects for any mapped disease, without knowledge of the specific founder mutation.

Adult↗
PubMed1999

Non-penetrance in a MODY 3 family with a mutation in the hepatic nuclear factor 1alpha gene: implications for predictive testing.

The most common cause of maturity-onset diabetes of the young (MODY) is a mutation in the hepatic nuclear factor 1alpha (HNF1alpha) gene (MODY3). We describe a family in which a missense mutation causing a Thr-Ile substitution at codon 620 has been found in all affected members. The mutation is not fully penetrant as two family members aged 87 and 46 have the mutation but do not have diabetes. The severity and age of diagnosis of diabetes varies widely within the family, and most presented over the age of 25. HNF1alpha mutation screening should be considered in any family with autosomal dominant inheritance of diabetes where one member has presented with diabetes before the age of 25. Predictive testing is now possible within the majority of MODY families, and is of clinical benefit, but the possibility of non-penetrance should be addressed during counselling and interpretation of results.

Adolescent↗
PubMed2006

Predictive testing for Huntington disease: interpretation and significance of intermediate alleles.

Direct mutation analysis for Huntington disease (HD) became possible in 1993 with the identification of an expanded CAG trinucleotide repeat as the mutation underlying the disease. Expansion of CAG length beyond 35 repeats may be associated with the clinical presentation of HD. HD has never been seen in a person with a CAG size of <36 repeats. Intermediate alleles are defined as being below the affected CAG range but have the potential to expand to >35 CAG repeats within one generation. Thus, children of intermediate allele carriers have a low risk of developing HD. Currently, the intermediate allele range for HD is between 27 and 35 CAG repeats. In this study, we review the current knowledge on intermediate alleles for HD including the CAG repeat range, the intermediate allele frequency, and the clinical implications of an intermediate allele predictive test result. The factors influencing CAG repeat expansion, including the CAG size of the intermediate allele, the sex and age of the transmitting parent, the family history, and the HD gene sequence and haplotype, will also be reviewed.

Age Factors↗
PubMed1985

The desferrioxamine test predicts bone aluminium burden induced by A1(OH)3 in uraemic patients but not mild histological osteomalacia.

Desferrioxamine (DFO), a chelating agent of aluminium was administered to 27 uraemic patients on chronic haemodialysis or haemofiltration with a minimal parenteral exposure to aluminium but taking various amounts of A1(OH)3 for about two years. All these patients had a double bone biopsy for measurement of their aluminium content and histomorphometric evaluation. Bone aluminium of our patients were 10 times greater than in our uraemic controls. Plasma aluminium increase (delta A1) induced by DFO correlated better than basal plasma aluminium with bone aluminium and cumulative dose of A1(OH)3 correlated with bone aluminium and delta A1 DFO. None of the patients had florid osteomalacia and only two had traces of aluminium staining. However 16 had mild mineralisation defect as demonstrated by low mineral appositional rate. The aluminium parameters were not different between the two groups of patients with or without mild mineralisation defect. It is concluded that the DFO test predicts bone aluminium but not mild histological osteomalacia in uraemic patients moderately aluminium over-loaded with phosphate binders.

Aged↗