Research priorities in hereditary hemochromatosis

Attitudes about and Psychosocial Outcomes of HFE Genotyping for Hemochromatosis

We examined attitudes regarding genetic testing and psychosocial outcomes of HFE genotyping for hemochromatosis. A total of 87 persons with hemochromatosis (patients) (39 women, 48 men), who underwent HFE genotyping, and 50 persons with hypertension (controls) (22 women, 28 men), who had not undergone HFE genotyping, completed a structured interview in which they reported attitudes about benefits and disadvantages of genetic testing and their understanding of genetics and hemochromatosis. Among patients, adherence to treatment for hemochromatosis was assessed. Controls estimated the likelihood of experiencing several potential positive and negative psychosocial outcomes after a positive genetic test. Patients reported their experience pertinent to these outcomes. Patients received information about hemochromatosis when they were diagnosed, and controls read a brief description of hemochromatosis before answering questions. Patients correctly answered 65% of knowledge questions and controls correctly answered 59%. Most participants believed genetic testing is beneficial and described few negative aspects of testing. Controls expected to experience more anxiety, depression, and anger related to a positive genetic test than was reported by patients (p < 0.001). One patient reported discrimination related to the HFE genotype. Most patients were compliant with the iron depletion and maintenance phases of treatment for hemochromatosis. Race, sex, marital status, income, education, barriers to treatment, and knowledge were not significantly associated with adherence to maintenance phlebotomy. We conclude that HFE genotyping appears to be viewed positively and would be generally accepted were it offered as part of a screening program for hemochromatosis. Persons who have not undergone genetic testing may overestimate their emotional responses to a positive test result. In the present hemochromatosis patients, few reported that HFE genotyping was accompanied by negative psychosocial outcomes.

Multiplex analysis of the most common mutations related to hereditary haemochromatosis: two methods combining specific amplification with capillary electrophoresis

We present the first application of a multiplex multicolour assay for the simultaneous detection of three of the most frequent mutations related to hereditary haemochromatosis (C282Y, H63D and S65C), using fluorescent detection and capillary electrophoresis. We describe two methods: the first is based on a single base extension assay, resulting in a single base difference of the extended products; and the second is a competitive allele-specific polymerase chain reaction (PCR), based on competition between allele-specific primers. Specificity of the latter primers is enhanced with a mismatch at the antepenultimate nucleotide. Primers are designed to amplify products of different sizes and with different fluorescent dyes in order to accurately distinguish all possible combinations of genotypes (homozygous and heterozygous for each mutation) in a multiplex PCR analysis. An advantage of the present approach is that capillary electrophoresis analysis of the amplified products enables easy, rapid, unambiguous and high resolution discrimination between wild-type and mutant alleles, although different mutations may be present in the multiplex analysis. This will facilitate automated genotyping for routine molecular diagnostics and large-scale genetic studies.

When and how should we screen for hereditary hemochromatosis?

Hemochromatosis is the clinical expression of iron overload and occurs as hereditary and secondary variants. In hereditary hemochromatosis, an inborn error in iron metabolism results in excess absorption of dietary iron, which gradually accumulates in the liver, pancreas, and heart. The most common form of hereditary hemochromatosis is related to homozygosity for the C282Y mutation in the HFE gene. Early diagnosis is essential because hereditary hemochromatosis is common, severe, and treatable. Early manifestations consist of asthenia, arthralgia, and serum transferrin saturation elevation. The C282Y mutation should be looked for to confirm the diagnosis in the patient and family members. Measurement of serum transferrin saturation followed by genetic testing in individuals with values above 45% is a reasonable screening strategy.

Hemochromatosis and Iron Overload Screening (HEIRS) study design for an evaluation of 100,000 primary care-based adults

BACKGROUND

The HEIRS Study will evaluate the prevalence, genetic and environmental determinants, and potential clinical, personal, and societal impact of hemochromatosis and iron overload in a multiethnic, primary care-based sample of 100,000 adults over a 5-year period. Participants are recruited from 5 Field Centers. Laboratory testing and data management and analysis are performed in a Central Laboratory and Coordinating Center, respectively.

METHODS

Participants undergo testing for serum iron measures and common mutations of the hemochromatosis gene ( ) on chromosome 6p and answer questions on demographics, health, and genetic testing attitudes. Participants with elevated values of transferrin saturation and serum ferritin and/or C282Y homozygosity are invited to undergo a comprehensive clinical examination (CCE), as are frequency-matched control subjects. These examinations provide data on personal and family medical history, lifestyle characteristics, physical examination, genetic counseling, and assessment of ethical, legal, and social implications. Primary and secondary causes of iron overload will be distinguished by clinical criteria. Iron overload will be confirmed by quantification of iron stores. Recruiting family members of cases will permit DNA analysis for additional genetic factors that affect iron overload.

RESULTS

Of the first 50,520 screened, 51% are white, 24% are African American, 11% are Asian, 11% are Hispanic, and 3% are of other, mixed, or unidentified race; 63% are female and 37% are male.

CONCLUSIONS

Information from the HEIRS Study will inform policy regarding the feasibility, optimal approach, and potential individual and public health benefits and risks of primary care-based screening for iron overload and hemochromatosis.

Screening for hemochromatosis

BACKGROUND

Hereditary hemochromatosis is the most common autosomal recessive disorder in populations of northern European descent.

ISSUES

Many experts consider hemochromatosis to be an almost ideal disease for population screening because it essentially fulfills almost all the criteria for screening proposed by the WHO. However, others disagree and suggest that more data are required particularly with regard to the natural history and penetrance of the disease. There is also disagreement about the best diagnostic/screening test for the disease and the performance of these tests in the context of screening. Other concerns are the variability and lack of standardization in screening test measurements, the selection of screening threshold values and the identification of false positive cases. The advent of a genetic test for the condition has brought other worries with regard to informed consent and the ethical, legal and social implications of screening particularly in relation to medical and general discrimination. Other important issues include compliance, cost effectiveness and the evidence that screening has lessened the burden of disease in the community.

CONCLUSIONS

At the present time, we believe that further data regarding both the exact disease burden and the outcomes of screening studies particularly in the general community are required before widespread population screening is introduced.

Use of consensus development to establish national research priorities in critical care

OBJECTIVES

To test the feasibility of using a nominal group technique to establish clinical and health services research priorities in critical care and to test the representativeness of the group's views.

DESIGN

Generation of topics by means of a national survey; a nominal group technique to establish the level of consensus; a survey to test the representativeness of the results.

SETTING

United Kingdom and Republic of Ireland.

SUBJECTS

Nominal group composed of 10 doctors (8 consultants, 2 trainees) and 2 nurses.

MAIN OUTCOME MEASURE

Level of support (median) and level of agreement (mean absolute deviation from the median) derived from a 9 point Likert scale.

RESULTS

Of the 325 intensive care units approached, 187 (58%) responded, providing about 1000 suggestions for research. Of the 106 most frequently suggested topics considered by the nominal group, 37 attracted strong support, 48 moderate support and 21 weak support. There was more agreement after the group had met-overall mean of the mean absolute deviations from the median fell from 1.41 to 1.26. The group's views represented the views of the wider community of critical care staff (r=0.73, P<0.01). There was no significant difference in the views of staff from teaching or from non-teaching hospitals. Of the 37 topics that attracted the strongest support, 24 were concerned with organisational aspects of critical care and only 13 with technology assessment or clinical research.

CONCLUSIONS

A nominal group technique is feasible and reliable for determining research priorities among clinicians. This approach is more democratic and transparent than the traditional methods used by research funding bodies. The results suggest that clinicians perceive research into the best ways of delivering and organising services as a high priority.

Screening for hereditary hemochromatosis: are DNA-based tests the answer?

Universal screening for hereditary hemochromatosis (HH) has been proposed by many experts, with understandable enthusiasm: HH can cause fatal complications, which are preventable with early treatment. The disorder involves excess iron accumulation that can result in tissue iron overload, with secondary cirrhosis, diabetes, heart failure, impotence and arthritis. These complications are preceded by years of iron accumulation, and most are believed to be preventable by removal of excess iron by phlebotomy. Thus, early identification and treatment - the quintessential functions of health screening - seem to make sense for HH. However, the available screening tests are imperfect. While they can identify many persons at increased risk from HH, the proportion that will develop serious clinical manifestations related to iron overload is not known with certainty. DNA-based tests do not provide a simple resolution to these questions.

Screening for hemochromatosis. A public health perspective

CONTEXT

The discovery of the HFE gene in 1996 has introduced DNA testing as a possible tool for screening and diagnosis of hemochromatosis and increased interest in the disorder. Population screening using transferrin saturation has been advocated by experts to permit early detection and treatment with phlebotomy before the onset of clinical disease.

METHODS

Based on a literature review, we consider the relative risks and merits of two screening tests as part of a broader look at the evidence required for the recommendation of universal screening for hemochromatosis.

RESULTS

Several questions must be answered before universal screening can be recommended. Uncertainties remain about the penetrance and preventable disease burden, laboratory standardization, and optimal strategies to minimize potential risks of screening for hemochromatosis.

CONCLUSIONS

As a common genetic disorder with simple, effective therapy, hemochromatosis offers a model for other genetically influenced chronic diseases that some day may have interventions to improve prognosis. Resolution of questions related to prevention of chronic diseases from hemochromatosis, therefore, will have broad usefulness in the future.