Estimate of the frequency of Wilson's disease in the US Caucasian population: a mutation analysis approach

The frequency of Wilson's disease in many populations is thought to be about one in 40000 persons, based on case and autopsy studies. Although the Wilson's disease gene has been identified, there is such a large number of mutations already known that it is not currently feasible to determine disease gene frequency by mutation analysis of a population. We have used a novel approach to obtain an estimate of the number of cases of Wilson's disease expected at birth in the US Caucasian population. We used data from four studies to determine that approximately one-third of Wilson's disease mutations in US Caucasian Wilson's disease patients are due to His-->Gln at the 1069 position. We then determined the frequency of this mutation in random DNA samples from 2601 US Caucasian newborns to be 0.285%. Multiplying by three gives an expected Wilson's disease heterozygote frequency of 0.855% and an allele frequency of 0.428%, or 0.00428. These data translate into a Wilson's disease frequency of about one in 55000 births. The 95% confidence interval is rather broad, ranging from about one in 18000 to one in 700000 births, but will be reduced as more data are added.

Fatty acids, alpha-fetoprotein, and cystic fibrosis

Docosahexaenoic acid, found lacking in animal models of cystic fibrosis, has been proposed as a dietary supplement therapy for this genetic disorder. Alpha-fetoprotein, which binds and transports docosahexaenoic acid, may be a useful marker to improve the management and follow-up in newborn screening programs for cystic fibrosis, because only 20% of such infants are diagnosed at birth.

The role of state public health agencies in genetics and disease prevention: results of a national survey

OBJECTIVES

The onset and severity of the clinical expression of most diseases that are of public health importance are influenced by genetic predisposition. The ability to assess human genetic predisposition for many diseases is increasing rapidly. Therefore, state public health agencies should be incorporating new developments in genetics and disease prevention into their core functions of assessment, policy development, and assurance. The authors assessed the status of this process.

METHODS

The Council of State and Territorial Epidemiologists (CSTE) surveyed states about projects and concerns related to genetics and public health activities. Respondents were the Health Officer, the Maternal and Child Health/Genetics Program Director, the Chronic Disease Program Director, and the Laboratory Director. Where applicable, responses were categorized into assessment, policy development, and assurance functions.

RESULTS

Thirty-eight (76%) state health departments responded. Ongoing genetics activities were assurance (82%), assessment (17%), and policy development (2%). In contrast, Health Officers responded that future genetics activities would be distributed differently: assurance, 41%; assessment, 36%; and policy development, 23%. Future assurance activities would be largely educational. Topics of interest and recently initiated activities in genetics were primarily assessment functions. Funding was the greatest concern, followed by lack of proven disease prevention measures and outcomes data.

CONCLUSIONS

State health departments recognize a need to realign their activities to meet future developments in genetics. Lack of adequate resources, proven disease prevention measures, and outcomes data are potential barriers. Public health agencies need to develop a strategic plan to meet the opportunities associated with the development and implementation of genetic tests and procedures.

Estimate of the frequency of Wilson's disease in the US Caucasian population: a mutation analysis approach

The frequency of Wilson's disease in many populations is thought to be about one in 40000 persons, based on case and autopsy studies. Although the Wilson's disease gene has been identified, there is such a large number of mutations already known that it is not currently feasible to determine disease gene frequency by mutation analysis of a population. We have used a novel approach to obtain an estimate of the number of cases of Wilson's disease expected at birth in the US Caucasian population. We used data from four studies to determine that approximately one-third of Wilson's disease mutations in US Caucasian Wilson's disease patients are due to His-->Gln at the 1069 position. We then determined the frequency of this mutation in random DNA samples from 2601 US Caucasian newborns to be 0.285%. Multiplying by three gives an expected Wilson's disease heterozygote frequency of 0.855% and an allele frequency of 0.428%, or 0.00428. These data translate into a Wilson's disease frequency of about one in 55000 births. The 95% confidence interval is rather broad, ranging from about one in 18000 to one in 700000 births, but will be reduced as more data are added.

Simultaneous measurement of antibodies to three HIV-1 antigens in newborn dried blood-spot specimens using a multiplexed microsphere-based immunoassay

We developed a fluorescent immunoassay to simultaneously measure antibodies to three HIV-1 antigens from newborn dried blood-spot specimens. The multiplexed assay uses fluorescent microspheres and a flow analyzer. The procedure is sensitive, precise and accurate, and can be expanded to simultaneously measure additional multiple analytes from a single specimen.

The role of state public health agencies in genetics and disease prevention: results of a national survey

OBJECTIVES

The onset and severity of the clinical expression of most diseases that are of public health importance are influenced by genetic predisposition. The ability to assess human genetic predisposition for many diseases is increasing rapidly. Therefore, state public health agencies should be incorporating new developments in genetics and disease prevention into their core functions of assessment, policy development, and assurance. The authors assessed the status of this process.

METHODS

The Council of State and Territorial Epidemiologists (CSTE) surveyed states about projects and concerns related to genetics and public health activities. Respondents were the Health Officer, the Maternal and Child Health/Genetics Program Director, the Chronic Disease Program Director, and the Laboratory Director. Where applicable, responses were categorized into assessment, policy development, and assurance functions.

RESULTS

Thirty-eight (76%) state health departments responded. Ongoing genetics activities were assurance (82%), assessment (17%), and policy development (2%). In contrast, Health Officers responded that future genetics activities would be distributed differently: assurance, 41%; assessment, 36%; and policy development, 23%. Future assurance activities would be largely educational. Topics of interest and recently initiated activities in genetics were primarily assessment functions. Funding was the greatest concern, followed by lack of proven disease prevention measures and outcomes data.

CONCLUSIONS

State health departments recognize a need to realign their activities to meet future developments in genetics. Lack of adequate resources, proven disease prevention measures, and outcomes data are potential barriers. Public health agencies need to develop a strategic plan to meet the opportunities associated with the development and implementation of genetic tests and procedures.

Consented testing of newborns and childbearing women for human immunodeficiency virus through a newborn metabolic screening program

OBJECTIVE

In this program a postpartum woman could consent to receive her newborn's human immunodeficiency virus test result from the New York State Newborn Screening Program.

STUDY DESIGN

By state regulation each postpartum woman was counseled and offered her newborn's human immunodeficiency virus test result. With the mother's consent, newborn human immunodeficiency virus antibody test results from the Newborn Screening Program were sent to the baby's pediatrician; otherwise, test results were blinded. Data were analyzed for births from August 1, 1996, to January 31, 1997.

RESULTS

Overall, 92.5% of women offered newborn human immunodeficiency virus testing consented to receive the result. Among 444 human immunodeficiency virus-positive women offered newborn testing, consented testing resulted in a 21.4% increase in knowledge of human immunodeficiency virus status from 72.3% (n = 321) at delivery to 93.7% (n = 416) after newborn testing; 6.3% (n = 28) of human immunodeficiency virus-positive women delivered of infants who did not consent apparently remained unaware of their human immunodeficiency virus status.

CONCLUSION

Combined prenatal and consented newborn testing identified 94% of human immunodeficiency virus-positive mothers and exposed newborns, allowing early entry into care. Such testing may provide an opportunity for women not previously tested for the human immunodeficiency virus to learn their status but is not a substitute for universal prenatal human immunodeficiency virus counseling and consented human immunodeficiency virus testing.

Rapid, efficient method for multiplex amplification from filter paper

Guthrie cards derived from the New York State Newborn Screening Program were utilized to develop a rapid, economical method for amplifying multiple genes to detect mutations that impact public health. These specimens are untraceable to the donor because identifiers are removed and discarded; therefore, these pilot studies were carried out anonymously. The sample preparation requires minimal manipulation, is amenable to automation, and is useful in laboratories which routinely process large numbers of samples, such as those in typical newborn screening laboratories. Multiple gene fragments may be amplified from a 1 mm punch which contains less than 1 microl of whole blood. The blood spots used in these studies contain sufficient material for up to 25 amplification reactions which multiplex at least four different gene fragments each. Since sufficient material remains on the card after the routine testing is complete, this simple assay can greatly expand the efficacy of current newborn screening programs by permitting DNA diagnosis of some disorders when indicated, particularly those in which genotype-phenotype correlations are useful. In addition to newborn screening specimens, this method is also applicable to whole blood from adults after phlebotomy and from lymphoblastoid cell lines. Use of filter paper for DNA analysis is particularly useful for shipped specimens or for population studies whose subjects are refractory to phlebotomy.

Cystic fibrosis carrier screening practices in an ethnically diverse region: experience of the Genetic Network of the Empire State, Puerto Rico, and the U.S. Virgin Islands

We surveyed clinical genetics centers to assess current cystic fibrosis (CF) screening practices with regard to clinical and laboratory aspects. The survey was developed by the CF committee of the Genetics Network of the Empire State, Puerto Rico, and the U.S. Virgin Islands (GENES) to gauge changes in trends following the April, 1997, NIH Consensus Statement recommending the offering of CF carrier screening to all pregnant patients. Thirty-five of 45 Centers (78%) returned the survey, which was mailed in June, 1998. Sixteen centers currently offer population-based screening, whereas 19 centers do not. Reasons cited for not offering testing included the low risk for CF in ethnic groups served, lack of data about test sensitivity in the populations served, and the absence of CF screening policies in the current standards of care. Approximately half (56%) of genetics centers that are offering testing altered their screening policy following the NIH Consensus statement, either by offering screening to patients of higher-risk ethnicities or by offering it to all patients. Less than half of the Centers that offer routine carrier screening offer screening to all patients regardless of ethnicity. This report is an initial step in documenting and understanding the current service practices regarding CF carrier testing in a diverse region. Our conclusions: (1) Screening practices vary widely among genetic centers in the region. (2) The decision to offer routine CF carrier screening is largely based on ethnicity of the patient population served. (3) Methods used to screen pregnant women and their partners in this part of the country reflect the diversity of models employed throughout the United States. (4) CF screening practices in the GENES region have changed significantly following the April, 1997, NIH consensus statement.

Multivariate discrimination for phenylketonuria (PKU) and non-PKU hyperphenylalaninemia after analysis of newborns' dried blood-spot specimens for six amino acids by ion-exchange chromatography

Ion-exchange HPLC was developed for testing dried blood-spot specimens from newborns. The method is suitable for quantitative confirmatory testing of abnormal specimens detected in the New York State Newborn Screening Program. Positive specimens were initially identified among all New York State newborns with semiquantitative bacterial inhibition assays (BIA) for aminoacidopathies, including phenylketonuria (PKU) and non-PKU hyperphenylalaninemia (HP), maple syrup urine disease, and homocystinuria. A selection of 1346 specimens from routine BIA screening, including 131 newborns with PKU or persistent HP, were tested by HPLC. Of 179 BIA results that were falsely positive, 98 (55%) were also falsely positive by HPLC in which the Phe/Tyr ratio was the discriminator and the threshold was set to attain 100% sensitivity. Investigation of three multivariate discriminatory methods revealed that linear discriminant analysis excluded all but 35 (20%) of the BIA false-positives.

An evaluation of the use of dried blood spots from newborn screening for monitoring the prevalence of cocaine use among childbearing women

A collaborative March of Dimes study was designed to examine the utility of dried blood spot (DBS) materials routinely collected from newborns as a source for monitoring cocaine exposure and to assess the prevalence of cocaine use among childbearing women in Georgia. We used a modified urinary radioimmunoassay (RIA) to anonymously detect the cocaine metabolite benzoylecgonine (BE) in DBSs. Extensive efforts were undertaken to assure absolute nonlinkage of BE data to any individual. The positive results found by RIA were confirmed by a mass spectrometry (MS) method specifically developed to detect BE in DBSs. BE was measured in 23,141 DBSs collected during 2 months of routine newborn screening in Georgia. A good correlation was observed for RIA results versus MS results (r2 = 0.97). The estimated minimal statewide BE prevalence was 4.8 per 1000 childbearing women. We demonstrated that immunoassay testing for cocaine without confirmatory testing can yield falsely elevated prevalence rates. When proper confirmatory testing is done, DBSs are a valuable source for population-based monitoring of substance abuse among childbearing women.

A fast hemoglobin variant on newborn screening is associated with alpha-thalassemia trait

Alpha thalassemia trait (alpha-thal-1) is a common cause of microcytosis in black and Asian populations. A small amount of hemoglobin Barts (2-8%) is transiently present in affected infants at birth and detectable in many newborn screening laboratories; it is a fast-moving hemoglobin on electrophoresis. In order to determine whether a report of a "fast hemoglobin variant" on newborn hemoglobinopathy screening is associated with a diagnosis of alpha thalassemia trait, hemoglobin concentration, red blood cell indices, and peripheral blood smear examination were performed on 18 infants referred for hematologic evaluation of a "fast hemoglobin variant" on newborn screening. All 18 infants with this diagnosis referred for consultation were black; ages ranged from 24 to 86 days (median 40 days). Six of 18 infants (33%) were mildly anemic for age and all 18 were microcytic. The prevalence of a "fast variant" among infants born at our institution is 2.5%. In that conditions other than alpha-thal-1 that cause microcytosis in early infancy are very uncommon, we conclude that all 18 of our infants with a fast hemoglobin on newborn screening likely have alpha-thal-1. The newborn screening result is thus a commonly and readily available laboratory report that specifically supports a diagnosis of alpha-thal-1, a diagnosis with significant clinical and genetic implications that is usually made only by exclusion.

Assessment of the aerosport TEEM 100 portable metabolic measurement system

The present study evaluated the utility of a portable metabolic measurement system, the Aerosport TEEM 100. A total of 505 data points [242 from incremental (INC) and 263 from constant load (CL) exercise] were collected on 12 subjects (age = 25 +/- 4 yr), by placing the Aerosport TEEM 100 medium flow pneumotach and mouthpiece in-line with a validated system, the Rayfield system. When VO2 values were separated into categories (< 1.5, 1.5-2.0, 2.0-2.5, 2.5-3.0, > 3.0 l.min-1), there was a small but statistically significant difference between the two metabolic measurement systems for VO2, VCO2, VE, RER, %ECO2, and %EO2 during both INC and CL exercise and measurement error for VO2 ranged between 2% and 11%. Correlations for VO2 values during INC and CL exercise between the two systems were r = 0.95 (SEest +/- 0.18 l.min-1) and r = 0.96 (SEest +/- 0.29 l.min-1), respectively. Correlations for RER were r = 0.82 (SEest +/- 0.08) and r = 0.47 (SEest +/- 0.11), for INC and CL, respectively. Results from the present investigation indicate that the Aerosport TEEM 100 has utility for the assessment of VO2, but the estimation of carbohydrate and fat utilization from RER should be used with caution.

Guidelines for the retention, storage, and use of residual dried blood spot samples after newborn screening analysis: statement of the Council of Regional Networks for Genetic Services

These guidelines provide scientific information for policy development by state health departments considering appropriate use of newborn screening specimens after screening tests are finished. Information was collected, debated, and formulated into a policy statement by the Newborn Screening Committee of the Council of Regional Networks for Genetic Services (CORN), a federally funded national consortium of representatives from 10 regional genetics networks. Newborn screening programs vary widely in approaches and policies concerning residual dried blood spot samples (DBS) collected for newborn screening. Recognition of the epidemiological utility of DBS samples for HIV seroprevalence surveys and a growing interest in DBSs for DNA analysis has intensified consideration of issues regarding retention, storage, and use of residual DBS samples. Potentially these samples provide a genetic material "bank" for all newborns nationwide. Their values as a resource for other uses has already been recognized by scientists, administrators, and judicial officials. Programs should promulgate rules for retention and use of residual newborn screening DBS samples based on scientifically valid information. Banking of newborn samples as sources of genetic material should be considered in light of potential benefit or harm to society.

The validity of regulating blood lactate concentration during running by ratings of perceived exertion

We examined whether ratings of perceived exertion (RPE) observed during an incremental (response) protocol could be used to produce target blood [HLa] of 2.5 mM and 4.0 mM during a 30-min treadmill run at a constant RPE. RPE (15.3, 17.6, 19.1), oxygen uptake (VO2) (3.31, 3.96, 4.00 l.min-1), velocity (V) (198, 218, 223 m.min-1), and heart rate (HR) (179, 185, 190 bpm) at blood [HLa] of 2.5 mM and 4.0 mM, and peak were determined for nine subjects (5 males, 4 females) during incremental exercise. Subjects then completed two 30-min runs at the RPE corresponding to blood [HLa] of 2.5 mM (RPE 2.5 mM) and 4.0 mM (RPE 4.0 mM) measured during the incremental protocol. For both 30-min runs, VO2 was not different from VO2 corresponding to either 2.5 or 4.0 mM blood [HLa] during the incremental test. During the 30-min run at RPE 2.5 mM: (a) only during minutes 25-30 was the blood [HLa] significantly different than 2.5 mM (3.2 +/- 0.6 mM, P < 0.05), (b) for the first 20 min HR was significantly lower than the HR at 2.5 mM during the incremental protocol, and (c) V did not differ from V at 2.5 mM during the incremental protocol. During the 30-min run at RPE 4.0 mM: (a) blood [HLa] was not significantly different from 4.0 mM, (b) HR at every time point was significantly lower than HR 4.0 mM during the incremental protocol, and (c) V was decreased over time by an average of 24.6 m.min-1 (P < 0.05). Because RPE from the response protocol was able to produce a blood [HLa] close to the criterion value during each 30-min run, we conclude that RPE is a valid tool for prescribing exercise intensities corresponding to blood [HLa] of 2.5 mM and 4.0 mM.

Comparison of newborn screening records and birth certificates to estimate bias in newborn HIV serosurveys

Implicit in the New York State Newborn HIV Seroprevalence Study is the assumption that newborns of all New York State residents are tested for human immunodeficiency virus (HIV) antibodies. We examined this assumption by describing that part of the 1988 New York newborn population not tested in the HIV seroprevalence study and assessing any bias contributed by this group. Of the expected total HIV specimens 1.5 percent were never received by the Newborn Screening Program, 0.5 percent were invalid specimens for which no repeat specimen could be obtained, and 1.7 percent were unsuitable or of insufficient quantity to be tested for HIV antibody. Thus 96.3 percent of all 1988 New York newborns were tested for HIV antibody. Black infants from New York City and low-birthweight infants were represented disproportionately among those not tested. Assignment of all untested newborn to HIV-positive status increased the seroprevalence rate 17 percent (0.64 percent to 0.75 percent).

Effects of testosterone on renal ornithine decarboxylase and kidney function

Testosterone injection caused a 2,000% increase in renal ornithine decarboxylase activity in intact male mice. A single injection of testosterone produced the same effect as repeated injections. The response was dose-dependent and could be blocked by actinomycin, diaminopropane, and cadaverine. Cycloheximide and putrescine had no inhibitory effect. Renal ODC response to arginine vasopressin was altered after castration; however, urine specific gravity and serum osmolality were unaffected by changes in renal ornithine decarboxylase activity.

Effects of a prolactin-secreting pituitary tumor on hypothalamic, gonadotropic and testicular function in male rats

The presence of a transplanted prolactin- and GH-secreting pituitary tumor (Furth MtT.215) in inbred male rats resulted in increased hypothalamic LHRH and pituitary LH content, decreased serum LH and testosterone concentrations, and very high serum prolactin values. The pituitary tumor also inhibited LH release by the in situ pituitary in response to orchidectomy, or orchidectomy, or adrenalectomy, and reduced the LH response to LHRH administration. Testes weight was significantly reduced and adrenal weight was significantly increased in the rats carrying pituitary tumors. These results that inhibitory effects of the transplanted pituitary tumor on LH and testosterone secretion were affected both a reduction in hypothalamic LHRH release and a reduced responsiveness of the pituitary to LHRH.

The effects of gamma-aminobutyric acid on prolactin and gonadotropin secretion in the unanesthetized rat

The effects of the intraventricular injection of gamma-aminobutyric acid (GABA) on pituitary secretion of luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin (PRL) were examined in Na-pentobarbital (PB)-anesthetized and unanesthetized male rats. GABA (5 or 10 millimicronmol) injected into the lateral ventricle of PB anesthetized rats resulted in significant elevations in plasma concentrations of LH and PRL. When administered via a lateral ventricle cannula to unanesthetized rats, GABA (1, 5, or 10 millimicronmol) caused a significant increase in plasma PRL levels but had no effect on plasm LH concentrations. Plasma FSH was uninfluenced by GABA in all animals studied. The data indicate that PB anesthesia can alter the hypothalamic pituitary axis to a possible neurotransmitter agent.

The effects of neurally active amino acids on prolactin secretion

Several neurally active amino acids were injected into the third ventricle of anesthetized male rats. Two or eight mumole of GABA produced significant increases in the plasma concentrations of prolactin (PRL), indicating increased PRL release from the pituitary. Two mumole of glycine was also effective in elevating PRL levels. The intraventricular injection of the lowest dose of GABA (1.0 mumole), glutamate (0.4 or 2.3 mumole), lysine (0.2 or 2.0 mumole), or 0.9% NaCl did not alter PRL levels significantly. Plasma PRL concentrations did not increase following the injection of GABA or glycine directly into the anterior pituitary gland. The results suggest that GABA and glycine may play a role in the neural regulation of PRL secretion.

The effects of neurally active amino acids on pituitary gonadotropin secretion

Several neurally excitant amino acids were injected into the third ventricle of anesthetized male rats, and plasma levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured. LH levels increased following injections of 2.0 mum glutamate, lysine, or beta-alanine. Glycine (2.0 mum), alpha-alanine (2.0 mum), and 0.9% saline were ineffective in altering LH levels. None of the amino acids tested significantly altered FSH levels. Of the 3 amino acids which raised blood LH levels following an intraventricular injection, i.e., glutamate, beta-alanine, and lysine, only lysine caused a significant increase in LH levels following injection into the pituitary. The present study provides evidence for a possible role for certain neurally excitant amino acids in the neuronal control of LH secretion.