Use of community genetic screening to prevent HFE-associated hereditary haemochromatosis

HFE-associated hereditary haemochromatosis is a recessive, iron-overload disorder that affects about one in 200 north Europeans and that can be easily prevented. However, genetic screening for this disease is controversial, and so we assessed whether such screening was suitable for communities. Cheek-brush screening for the Cys282Tyr HFE mutation was offered to individuals in the workplace. Outcomes were assessed by questionnaires before and after testing. 11,307 individuals were screened. We recorded no increase in anxiety in individuals who were homozygous for the Cys282Tyr mutation or non-homozygous. Self-reported tiredness before testing was significantly higher in homozygous participants than in non-homozygous participants (chi2 test, p=0.029). Of the 47 homozygous individuals identified, 46 have taken steps to treat or prevent iron accumulation. Population genetic screening for HFE-associated hereditary haemochromatosis can be practicable and acceptable.

Induction of uterine prostaglandin H synthase 2 by estradiol following fetal adrenalectomy

In sheep, fetal cortisol stimulates the conversion of progesterone to estradiol in late gestation initiating labor. It is unclear whether an intact fetal hypothalamic-pituitary-adrenal (HPA) axis is required to induce the estradiol-triggered subsequent endocrine changes including enhanced intrauterine prostaglandin (PG) synthesis associated with the onset of labor. We have shown that maternal estradiol administration stimulates PG H synthase (PGHS)-2 expressions in pregnant ovine intra-uterine tissues. The current study was undertaken to determine whether the fetal adrenal mediates estradiol's stimulation of the intrauterine PGHS-2 in pregnant sheep. Placenta, myometrium, and endometrium were collected from two groups of ewes at 123-127 d of gestational age (dGA) after fetal adrenalectomy and vehicle treatment (ADX; n = 5); or fetal ADX and maternal estradiol administration (5 mg twice a day for 2 d, ADX+E2, n = 5). PGHS-2 mRNA and protein were analyzed by Northern and Western Blot analyses in both groups and presented as the ratios to beta actin mRNA for Northern and G protein beta subunit for Western blot analysis. Fetal plasma cortisol was measured by radioimmunoassay. Data were analyzed by Student's t test. Fetal plasma cortisol levels were low in ADX and ADX+ E2 groups (<6 ng/mL). The cervix of all ADX+E2 treated ewes was dilated at necropsy. Three out of five ADX+ E2-treated ewes delivered within 48 h. The cervix was closed in all fetal ADX ewes at necropsy. PGHS-2 mRNA and protein increased (p < 0.05) in myometrium and endometrium, but not placenta in ADX+E2-treated ewes compared with ADX group. These data provide the first in vivo evidence for estradiol upregulation of intrauterine PGHS-2 in late gestation in the absence of an intact fetal HPA axis. Thus, the fetal adrenal is not required to mediate estradiol's stimulation of uterine PGHS-2 expression associated with the onset of labor.

Implementation of HaemScreen, a workplace-based genetic screening program for hemochromatosis

There is debate as to whether community genetic screening for the mutation(s) causing hereditary hemochromatosis (HH) should be implemented, due to issues including disease penetrance, health economic outcomes, and concerns about community acceptance. Hemochromatosis is a common preventable iron overload disease, due in over 90% of cases to C282Y homozygosity in the HFE gene. We are, therefore, piloting C282Y screening to assess understanding of genetic information and screening acceptability in the workplace setting. In this program, HaemScreen, education was by oral or video presentation in a group setting. C282Y status was assessed by polymerase chain reaction (PCR) and melt-curve analysis on DNA obtained by cheek-brush sampling. Of eligible participants, 5.8% (1.5-15.8%) attended information and screening sessions, of whom 97.7% (5571 individuals) chose to be tested. Twenty-two C282Y (1 : 253) homozygotes were identified and offered clinical follow-up. There were 638 heterozygotes (1 : 8.7). The determinants for participation have been analyzed in terms of the principles outlined in the Health Belief Model. Widespread screening for HH is readily accepted in a workplace setting, and a one-to-many education program is effective. The level of participation varies greatly and the advertizing and session logistics should be adapted to the specific features of each workplace.

Cancer worries, risk perceptions and associations with interest in DNA testing and clinic satisfaction in a familial colorectal cancer clinic

Multi-disciplinary familial cancer clinics are becoming an integral part of cancer services. It is, therefore, important to assess how attendance at these clinics impacts on cancer-related concerns, risk perceptions and behavioural intentions, and how the clinic services are being received by those using them. This study has assessed a familial colorectal cancer clinic with respect to cancer-related worries and risk perceptions and their impact on interest in DNA testing and overall satisfaction with the clinic. Pre- and post-clinic questionnaires were completed by 127 patients and relatives attending the clinic. After attending the clinic, the proportion of people 'very' or 'extremely' worried about developing bowel cancer reduced from 49 (pre-clinic) to 34% (p = 0.002). Worry about bowel cancer was positively associated with younger age, higher education level and higher perceived risk of developing cancer. A reduction in level of risk perception correlated with a lower likelihood of feeling 'very worried' about developing bowel cancer. Of those intending to go ahead with DNA testing, 58% were 'very worried' about bowel cancer compared with 15% of those not intending to proceed with testing, suggesting that worry was a motivation for interest in DNA testing. One-third of participants indicated another session of genetic counselling would be helpful. Within this group, a higher proportion was very worried about bowel cancer (43%) than for those who did not want another session (17%). Attendance at this familial colorectal cancer clinic alleviated worry for many individuals, partly due to improved information about risk of colorectal cancer.

High frequency hearing loss correlated with mutations in the GJB2 gene

Genetic hearing impairment affects approximately 1/2000 live births. Mutations in one gene, GJB2, coding for connexin 26 cause 10%-20% of all genetic sensorineural hearing loss. Mutation analysis in the GJB2 gene and audiology were performed on 106 families presenting with at least one child with congenital hearing loss. The families were recruited from a hospital-based multidisciplinary clinic, which functions to investigate the aetiology of sensorineural hearing loss in children and which serves an ethnically diverse population. In 74 families (80 children), the aetiology was consistent with non-syndromic recessive hearing loss. Six different connexin 26 mutations, including one novel mutation, were identified. We show that GJB2 mutations cause a range of phenotypes from mild to profound hearing impairment and that loss of hearing in the high frequency range (4000-8000 Hz) is a characteristic feature in children with molecularly diagnosed connexin 26 hearing impairment. We also demonstrate that this type of audiology and high frequency hearing loss is found in a similar-sized group of deaf children in whom a mutation could only be found in one of the connexin 26 alleles, suggesting connexin 26 involvement in the aetiology of hearing loss in these cases. In our study of the M34T mutation, only compound heterozygotes exhibited hearing loss, suggesting autosomal recessive inheritance.

Assessment of education and counselling offered by a familial colorectal cancer clinic

We have evaluated whether or not client expectations, in terms of education and information needs, have been met by a multi-disciplinary familial colorectal cancer clinic. The study used a pre- and post-clinic questionnaire design and 126 (84 women, 42 men) clients of the clinic participated. The most common reason for coming to the clinic is to 'find out whether there is a gene for colorectal cancer in the family', followed by 'to reduce risk for bowel cancer' and 'concern for children's risk'. Clients would have preferred to receive more information before attendance at the clinic to help with preparation. Information given during the clinic increased knowledge of bowel cancer genetics and had a positive effect on the accuracy of some clients' perceptions of their risk of developing cancer. In multivariate analysis, higher risk perceptions, higher education level and greater baseline knowledge predicted post-clinic knowledge of bowel cancer genetics and an increase in knowledge. Client reports of the presence of a genetic counsellor or medical geneticist in the session also predicted post-clinic knowledge and an increase in knowledge. Most participants felt they received enough information during the clinic session on various aspects of familial colorectal cancer, but the desire for more written information on prevention, including lifestyle actions, was expressed by many.

Clinical and genetic study of Friedreich ataxia in an Australian population

Friedreich ataxia is an autosomal recessive disorder caused by mutations in the FRDA gene that encodes a 210-amino acid protein called frataxin. An expansion of a GAA trinucleotide repeat in intron 1 of the gene is present in more than 95% of mutant alleles. Of the 83 people we studied who have mutations in FRDA, 78 are homozygous for an expanded GAA repeat; the other five patients have an expansion in one allele and a point mutation in the other. Here we present a detailed clinical and genetic study of a subset of 51 patients homozygous for an expansion of the GAA repeat. We found a correlation between the size of the smaller of the two expanded alleles and age at onset, age into wheelchair, scoliosis, impaired vibration sense, and the presence of foot deformity. There was no significant correlation between the size of the smaller allele and cardiomyopathy, diabetes mellitus, loss of proprioception, or bladder symptoms. The larger allele size correlated with bladder symptoms and the presence of foot deformity. The duration of disease is correlated with wheelchair use and the presence of diabetes, scoliosis, bladder symptoms and impaired proprioception, and vibration sense but no other complications studied.

Influenza outbreak in a long-term-care facility: considerations for pharmacy

The role played by a hospital pharmacy department in managing an influenza outbreak at an affiliated long-term-care facility is described. In February 1998 an outbreak of influenza A was confirmed in a 570-bed long-term-care facility. During the outbreak, a total of 48 cases of influenza-like illness (ILI) were reported to infection control, and 62 staff members missed work because of ILI. Infection control measures included a recommendation for prophylaxis with amantadine. Pharmacists assumed responsibility for educating patients and families about amantadine prophylaxis, providing individualized dosing, evaluating reported adverse effects, and drug distribution. Pharmacists developed an information sheet on amantadine for patients and met with patients and their families. The overall acceptance rate for chemoprophylaxis was 91%. Of the 349 patients receiving amantadine during the outbreak, 203 (58%) were given 100 mg daily, 136 (39%) were given 100 mg every other day, and 10 (3%) were prescribed 100 mg weekly. Pharmacists confirmed a total of 22 adverse effects; generally the problem was solved by reducing the dosage rather than discontinuing the drug. In all cases, the first dose of amantadine was provided to the nursing units within three hours of an order being written. Pharmacists played an active role in managing an influenza A outbreak at a long-term-care facility.

Screening high-risk patients for methicillin-resistant Staphylococcus aureus on admission to the hospital: is it cost effective?

OBJECTIVES

To determine the cost-effectiveness of a policy of screening high-risk patients for methicillin-resistant Staphylococcus aureus (MRSA) colonization on admission to hospital.

SETTING

980-bed university-affiliated tertiary-care hospital.

PATIENTS

Between June 1996 and May 1997, patients directly transferred from another hospital or nursing home, or who had been hospitalized in the previous 3 months, were screened for MRSA within 72 hours of hospital admission.

DESIGN

Nasal, perineal, and wound swabs were obtained for MRSA screening using standard laboratory methods. Laboratory and nursing costs associated with screening patients for MRSA on admission to hospital were calculated. The costs associated with the implementation of recommended infection control measures for patients with MRSA also were determined.

RESULTS

3,673 specimens were obtained from 1,743 patients. MRSA was found on admission in 23 patients (1.3%), representing 36% of the 64 patients with MRSA identified in the hospital during the year. MRSA-colonized patients were more likely to have been transferred from a nursing home (odds ratio [OR], 6.4; P =.04) or to have had a previous history of MRSA colonization (OR, 13.1; P =.05). Laboratory and nursing costs were found to be $8.34 per specimen, for a total cost of $30,632 during the year. The average cost of implementing recommended infection control measures for patients colonized with MRSA was approximately $5,235 per patient.

CONCLUSION

If early identification of MRSA in colonized patients prevents nosocomial transmission of the organism to as few as six new patients, the screening program would save money.

Risk factors for coronary heart disease in a population with a high prevalence of obesity and diabetes: a case-control study of the Polynesian population of Western Samoa

OBJECTIVE

To evaluate anthropometric, haemodynamic and biochemical risk markers for coronary heart disease (CHD) in the Polynesian population of Western Samoa in a case-control study of 43 cases of CHD compared with 90 age- (mean 53 years) and sex-matched controls.

METHODS

Cases were identified on the basis of a 12-lead electrocardiogram and clinical history.

RESULTS

More than 60% of the participants had a body mass index > or =30 kg/m2 and nearly 80% had central obesity. Both diabetes mellitus (17%) and impaired glucose tolerance (9%) were also common in this population. Nineteen per cent of the population were hypertensive and both antihypertensive therapy (21 versus 1%, P<0.001, risk 23.6) and hypertension (35 versus 11%, P<0.01, risk 4.3) were significantly more common among cases than they were among controls. In addition, the plasma high-density lipoprotein cholesterol level was lower (1.00+/-0.09 versus 1.24+/-0.05 mmol/l, P<0.05) and the plasma urate level was higher (0.42+/-0.02 versus 0.37+/-0.01 mmol/l, P<0.05) in the female cases than they were in their respective controls. Low-density lipoprotein (LDL) particle sizing did not reveal an excess of small LDL particles to be a feature of CHD cases, but more than 70% both of cases and of controls had multiple LDL species. The response of the triglyceride level to a fat-rich meal was the same for CHD cases and controls.

CONCLUSION

The population studied had a high prevalence of several risk factors for CHD, including obesity and non-insulin-dependent diabetes mellitus; however, the most prominent factor relating to CHD within the community was the presence of hypertension.

Hyperleptinaemia: the missing link in the, metabolic syndrome?

Leptin's association with fasting insulin raises the possibility that hyperleptinaemia is an additional component of the Metabolic Syndrome, or perhaps underlies the syndrome. This population-based study of Western Samoans examined the relationship of serum leptin with insulin sensitivity assessed by Homeostatic Model Assessment (HOMA) and components of the Metabolic Syndrome. Two hundred and forty subjects (114 men, 126 women), aged 28-74 years, were drawn from a study conducted in 1991. An oral glucose tolerance test indicated that 59 subjects had diabetes. Diabetic men had higher leptin levels than non-diabetic (6.0 vs 3.2 ng ml-1) but this difference was no longer significant after adjustment for BMI. Leptin levels in diabetic women (24.7 ng ml-1) non-diabetic women (22.6 ng ml-1) were not different. Leptin was strongly, positively correlated with BMI, fasting insulin and mean blood pressure after adjusting for age and sex (r > 0.43, p < 0.001), irrespective of glucose tolerance status. Linear regression models indicated that leptin was associated with insulin sensitivity independent of age, BMI, waist/hip ratio, triglycerides, HDL-cholesterol, and hypertension. Similar models were computed with mean blood pressure or triglycerides as the dependent variable, and including insulin sensitivity with the independent variables. Leptin was independently associated with mean blood pressure in men, but was not independently associated with triglycerides. Mean levels of 2-h insulin, triglycerides, LDL-cholesterol, and systolic blood pressure varied across tertiles of leptin in men after adjusting for age, BMI, and insulin sensitivity, and mean levels in the top tertile tended to be higher than in the lowest tertile. These results indicate an independent relationship between leptin and insulin sensitivity, but the equivocal results concerning associations of leptin with components of the Metabolic Syndrome make it unlikely that leptin affects these directly.

Blood pressure, hypertension and other cardiovascular risk factors in six communities in Papua New Guinea, 1985-1986

Surveys of noncommunicable diseases were performed in six communities in Papua New Guinea during 1985-1986. Results are reported here with respect to blood pressure and associated factors in adults. Mean systolic and diastolic blood pressures were lowest, and hypertension was rarest (less than 2%), in three rural/semirural villages on Karkar Island, Madang Province. Intermediate values for blood pressure and moderate prevalence of hypertension (3-6%) were observed in rural and urban Tolai communities in East New Britain Province. A periurban village in the Eastern Highlands Province displayed the highest mean blood pressures and prevalence of hypertension (12% in men and 5% in women). There was a modest rise in mean systolic blood pressure with age in most groups, but the age-related rise in diastolic pressure was much less pronounced. Other cardiovascular risk factors--body mass index (BMI), and plasma cholesterol, glucose and insulin concentrations--were lowest in the least developed rural villages on Karkar Island and highest in the urban Tolai and periurban highland communities. Both systolic and diastolic blood pressures were significantly (and positively) related to age, male sex, BMI and speaking a non-Austronesian language. It is concluded that there is now a considerable variation in the prevalence of hypertension, and the levels of blood pressure and other cardiovascular risk factors, in different communities in Papua New Guinea.

Performance of 'Micro-Bumintest' tablets for detection of microalbuminuria in Nauruans

Subclinical elevation of urinary albumin excretion (microalbuminuria) is useful for the detection of individuals at high risk of developing nephropathy in both insulin-dependent and non-insulin-dependent diabetes mellitus. We have evaluated the performance of Micro-Bumintest, a semi-quantitative test for the rapid detection of microalbuminuria. A total of 1186 samples from a population-based survey of the high diabetes prevalence community of Nauru were studied. Compared with a radioimmunoassay method, the Micro-Bumintest had a sensitivity of 97.6%, specificity of 93.2% and overall efficiency of 94.8%, when 40 micrograms/ml was used as the discriminating albumin concentration defining microalbuminuria. Significant differences in radioimmunoassay results between categories of the Micro-Bumintest were found, indicating its usefulness as a semi-quantitative test. Compared with subjects with normal glucose tolerance, there was a statistically significant progressive increase in the prevalence of microalbuminuria as detected by Micro-Bumintest in subjects with impaired glucose tolerance and diabetes mellitus. Micro-Bumintest performs well as a screening test for detection of microalbuminuria not only in the clinical situation, but also in population-based epidemiological studies.

Group comparisons of blood pressure and indices of obesity and salt intake in Pacific populations

Group comparisons of blood pressure and indices of obesity and salt intake from epidemiological studies conducted in the Pacific early in the 1980s are presented. The comparisons were of a rural-urban type, and showed a trend for a lower prevalence of hypertension and for lower mean blood pressures in adults from rural areas, compared with urban populations. Rural residents were also slimmer and appeared to have a lower salt intake than did urban dwellers. These findings give possible support to the role of adiposity and salt intake in the genesis of essential hypertension.

Impaired glucose tolerance in Kiribati

Subjects with impaired glucose tolerance have been shown to have a higher risk for subsequent diabetes and increased susceptibility to atherosclerosis. Data obtained from a cross-sectional medical survey in Kiribati in 1981 have been studied for evidence as to whether impaired glucose tolerance is a truly separate category of glucose intolerance. Subjects in the impaired glucose tolerance category were compared to both normal and diabetic subjects with respect to the mean values of certain variables including plasma glucose, body mass index, plasma cholesterol, plasma triglycerides, and systolic blood pressure. Differences between impaired glucose tolerant and normal subjects, and between impaired glucose tolerant and diabetic subjects were assessed. The most important differences between groups occurred with respect to plasma glucose concentration, body mass index, and plasma lipids. The results of this study provide further support for the validity of the impaired glucose tolerance category.

Ethnic differences in susceptibility to non-insulin-dependent diabetes. A comparative study of two urbanized Micronesian populations

Two urbanized Micronesian populations were recently studied by population-based diabetes surveys. These were Nauruans living on the island of Nauru, and Gilbertese resident on the islet of Betio, in the Republic of Kiribati (1982 and 1981, respectively). Nauruans are known to suffer from a very high prevalence of non-insulin-dependent (type II) diabetes mellitus (NIDDM). In the present study, the effects of suspected environmental risk factors for diabetes were controlled for, in an attempt to elucidate any residual difference in the prevalence of diabetes between the two groups, which might be of genetic origin. As almost all Nauruans lead a physically inactive lifestyle, only inactive subjects in either population were selected for study. The total study sample consisted of 2306 subjects. After further controlling for the effects of age and obesity, the odds of diabetes for Nauruans, as compared with Gilbertese, were threefold. The multiple logistic regression model showed ethnicity (i.e., being Nauruan) to be the strongest of the predictor variables examined in both sexes. In a random subsample of approximately one-third of the total subjects (N = 694), stratified with respect to age and sex, daily intake of total energy and of three dietary components was assessed. The dietary variables were carbohydrate, fat, and dietary fiber. Fat intake was found to be a weak, but significant predictor of diabetes in females after controlling for age, although dietary fat was not predictive of diabetes after also controlling for ethnicity, or for body mass. None of the other dietary variables had any predictive power in either sex.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucose tolerance in a highland population in Papua New Guinea

A diabetes survey was conducted in the highlands of Papua New Guinea in June 1983. Two villages in the Asaro Valley, Eastern Highlands Province, were selected for study. The subjects were of Melanesian ancestry, and were free of Austronesian genetic admixture. The response rate was 95% and 308 subjects were examined. As defined by current WHO criteria, there was a total absence of non-insulin-dependent diabetes (NIDDM) in these communities. The prevalence of impaired glucose tolerance (IGT) was 2%. These estimates of glucose intolerance are the lowest yet to be reported from the Pacific, using currently accepted diagnostic criteria and standardized survey methods. The 2-hr plasma glucose and insulin concentrations were positively correlated in both sexes. Of the two villages studied, one had undergone a greater degree of acculturation than the other. Both the total distribution and the mean value of 2-hr plasma glucose concentration were lower in the more traditional village, and these findings could not be explained by differences in age or obesity between the two communities. Mean 2-hr plasma insulin concentration did not differ significantly between the two villages, and was very low in both. The results of this study support the theory that Melanesians free of Austronesian genetic admixture are relatively, though not absolutely resistant to the deleterious influence of acculturation upon glucose tolerance seen in other Pacific populations. However, the notion that in this population cultural change has been insufficient, or of too recent onset for a deterioration in glucose tolerance to be manifest cannot be excluded.

Plasma glucose distributions in two pacific populations: the bimodality phenomenon

The frequency distribution of plasma glucose concentrations in certain populations show two distinct sub-groups, viz. the non-diabetic group and a hyperglycaemic group. The two groups show up as a double peak (bimodality) in the best-fit frequency distributions of log plasma glucose, and the separation or cut-off point where the two curves intersect, gives an indication of the plasma glucose level at which diabetes could be diagnosed. Venous plasma glucose concentrations two hours after a 75 gm oral glucose load were determined in the Micronesian population of Nauru and the urban Polynesian population of Western Samoa, in subjects aged 20 years and over. Both communities exhibit bimodal frequency distributions of plasma glucose in the upper age groups in both sexes. In the younger age groups the frequency distribution of plasma glucose typically follows the usual unimodal Gaussian curve. However, the high prevalence Nauruans show the bimodal form in all groups except the youngest males. The data show that among these two communities, as with the Pimas, the frequency distribution of plasma glucose concentrations can be used to separate the population into normal and hyperglycaemic groups.