Single-nucleotide polymorphism alleles in the insulin receptor gene are associated with typical migraine.

We have identified a migraine locus on chromosome 19p13.3/2 using linkage and association analysis. We isolated 48 single-nucleotide polymorphisms within the locus, of which we genotyped 24 in a Caucasian population comprising 827 unrelated cases and 765 controls. Five single-nucleotide polymorphisms within the insulin receptor gene showed significant association with migraine. This association was independently replicated in a case-control population collected separately. We used experiments with insulin receptor RNA and protein to investigate functionality for the migraine-associated single-nucleotide polymorphisms. We suggest possible functions for the insulin receptor in migraine pathogenesis.

Family consent and the pursuit of better medicines through genetic research.

Rapid changes in the science and technology related to genetic research are challenging scientists, health care providers, ethicists, regulators, patient groups, and the pharmaceutical industry to keep pace with ethically grounded, workable guidelines for both the research and clinical applications of human genetics. We describe the genetic research being conducted by one pharmaceutical company (GlaxoSmithKline) and how the company is addressing the ethical, legal, and social issues surrounding this research; discuss an industry working group's attempt to advance pharmacogenetic research by openly addressing and disseminating information on related ethical, legal, and regulatory issues; identify scientific and ethical differences among various types of genetic research; discuss potential implications of family consent on subject privacy and autonomy, data collection, and study conduct; and suggest points to consider when study sponsors, investigators, and ethics committees evaluate research proposals. Public and expert opinion regarding informed consent in genetic research is evolving as a result of increased education, discussion, and understanding of the relevant issues. Five years ago, there was strong support for anonymity in genetic research as a privacy safeguard. Now, an increasingly popular school of thought advocates against anonymity to preserve an individual's ability to withdraw and, if desired, access research results. It is important to recognize this evolution and address consent issues in a reasoned, practical, and consistent way, including input from patients and their families, health care providers, ethicists, scientists, regulatory bodies, research sponsors, and the lay community. Responsibility for assessing issues related to family consent for research should remain with local investigators, ethics boards, and study sponsors. A "one-size-fits-all" perspective in the form of new regulations, for example, would likely be a disservice to all.

Pharmacogenetics: the Rx perspective.

Pharmacogenetics is changing the way medicines are discovered, developed and delivered to patients. In this article, we present the 'prescription' perspective--how the results of pharmacogenetic research will help minimize the risk of costly adverse drug reactions and treatment failures, by providing predictive tools to enable healthcare providers to prescribe the right medicine for the right patient. We discuss the challenges of this research and its clinical application; its implications for drug development; evolving concepts of informed consent; related ethical, legal and social issues; changing definitions of 'genetic testing'; and the creation of an international Pharmacogenetics Working Group.

Applications of pharmacogenetics to drug development: the Glaxo Wellcome experience.

The Genetics Directorate was established at Glaxo Wellcome (GW) in 1997. The goals of the Directorate are to identify susceptibility genes for common diseases with large unmet therapeutic need, apply genetic methods for the targeted development of medicines so that the right medicine is developed for the right patient, assist in translating gene discoveries into target selection, and represent genetics accurately internally within GW and externally (to laypersons, the medical community, the business community, government representatives, and regulatory agencies). As part of the goal of developing the right medication for the right patient, GW has added genetic research to its clinical drug studies in every major therapeutic area. GW worked closely with international ethicists experienced in the area of genetic research to develop the process and documents that are currently in use; these undergo frequent, rigorous review in light of the changing regulatory and legal environment and the needs of clinical investigators and patients. The addition of genetic research to clinical studies was accompanied by significant education efforts within GW and for study-site personnel, ethics committees, and regulatory authorities. Feedback from all those involved is an integral part of implementing GW's genetic research and is used to fine-tune the processes and protocol and consent document templates. A recently completed review of the approval rate from ethics committees in several countries has revealed trends in EC/IRB (Ethics Committees/Institutional Review Boards) questions and concerns about genetic research. This article will focus on the lessons learned from incorporating genetic research into clinical studies at over 1,500 international sites and will include summaries of the feedback from investigators, EC/IRBs, and regulatory authorities. It also will include a discussion of the potential applications of SNP (single nucleotide polymorphism) map technologies to pharmacogenetics by increasing the ability to correlate patients' genetic information with their response to medicines.

A placebo-controlled trial of lamotrigine add-on therapy for partial seizures in children. Lamictal Pediatric Partial Seizure Study Group.

OBJECTIVE: To compare the safety and efficacy of add-on lamotrigine and placebo in the treatment of children and adolescents with partial seizures. BACKGROUND: Add-on and monotherapy lamotrigine is safe and effective in adults with partial seizures, and reports of preliminary uncontrolled trials suggest similar benefits in children. METHODS: We studied 201 children with diagnoses of partial seizures of any subtype currently receiving stable conventional regimens of antiepileptic therapy at 40 study sites in the United States and France. After a baseline observation period (to confirm that more than four seizures occurred in each of two consecutive 4-week periods), patients were randomized to add-on lamotrigine or placebo therapy. A 6-week dose-escalation period was followed by a 12-week maintenance period. RESULTS: Compared with placebo, lamotrigine significantly reduced the frequency of all partial seizures and the frequency of secondarily generalized partial seizures in these treatment-resistant patients. The most commonly reported adverse events in the lamotrigine-treated patients were vomiting, somnolence, and infection; the frequency of these and other adverse events was similar to that in the placebo-treated group, with the exception of ataxia, dizziness, tremor, and nausea, which were more frequent in the lamotrigine-treated group. The frequency of withdrawals for adverse events was similar between groups. Two patients were hospitalized for skin rash, which resolved after discontinuation of lamotrigine therapy. CONCLUSIONS: Lamotrigine was effective for the adjunctive treatment of partial seizures in children and demonstrated an acceptable safety profile.

Lamictal (lamotrigine) monotherapy for typical absence seizures in children.

PURPOSE: To investigate whether lamotrigine (LTG) monotherapy is effective and safe for newly diagnosed typical absence seizures in children and adolescents (aged 3-15 years, n = 45). METHODS: A "responder-enriched" study design was used: open-label dose escalation was followed by placebo-controlled, double-blind testing of LTG. Conventional hyperventilation testing with EEG recording was used to confirm diagnoses and assess treatment success defined as complete freedom from seizures. Ambulatory 24-h EEG recordings provided supporting evidence of effectiveness. Safety was assessed by evaluation of adverse events, vital signs, and physical, neurologic, and laboratory examinations. Plasma samples were taken to evaluate the pharmacokinetics of LTG. RESULTS: During initial open-label dose escalation, 71.4% of patients (intent-to-treat) or 82% (per protocol analysis) became seizure free; individual patients responded at doses ranging from 2 to 15 mg/kg/day (median, 5.0). In the placebo-controlled, double-blind phase of the study, statistically significantly more patients remained seizure free when treated with LTG (62%) than with placebo (21%; p < 0.02; for the intent-to-treat analysis). Mean plasma concentrations of LTG, were linearly related to dose, although there was substantial interindividual variation. No patients were withdrawn from the study for any safety-related reason. CONCLUSIONS: LTG monotherapy is effective for typical absence seizures in children and is generally well tolerated.

Ontogeny of gonadotrophin and inhibin secretion in normal girls through puberty based on overnight serial sampling and a comparison with normal boys.

We measured luteinizing hormone (LH) and follicle stimulating hormone (FSH) by immunofluorometric assays and alpha-inhibin by radioimmunoassay in serum sampled every 10 min throughout the night (2100-0500 h) from 44 normal girls. Mean overnight LH values rose log-linearly from a mean of 0.2 IU/l in prepubertal girls to 3.0 IU/l in late pubertal girls. Log2 mean overnight FSH rose rapidly through early puberty and then remained constant; mean FSH rose from 1.0 IU/l in prepubertal girls to approximately 2.8 IU/l in Tanner III-V girls. Mean overnight inhibin increased through puberty, rising from 151 ng/l in prepubertal girls to 432 ng/l in fully pubescent girls. Within each of the first three Tanner stages, LH differed approximately 100-fold between the smallest and largest mean concentrations but differed <10-fold within stages IV or V. Such within-pubertal stage variability was less pronounced for FSH, which differed approximately 16-fold among Tanner I subjects and 4-10-fold at later stages, and for inhibin, which varied approximately 4-fold within each Tanner stage. The frequency of LH pulses during overnight sampling increased significantly during puberty, but the frequency of FSH and inhibin pulses remained constant. We compared the results from girls to those from 50 normal boys [Manasco et al. (1995) J. Clin. Endocrinol. Metab., 80, 20462052]. At each pubertal stage, girls had approximately the same mean overnight LH values as boys; girls had higher mean overnight FSH, particularly during Tanner stages II-IV; and boys had mean overnight alpha-inhibin immunoreactivity approximately 1.5 times that of girls at each pubertal stage. Still, hormone concentrations for individuals of both sexes intergraded at each pubertal stage.

Lamotrigine for generalized seizures associated with the Lennox-Gastaut syndrome. Lamictal Lennox-Gastaut Study Group.

BACKGROUND: The Lennox-Gastaut syndrome, a severe form of epilepsy that usually begins in early childhood, is difficult to treat. Dose-related drug toxicity is common. METHODS: We conducted a double-blind, placebo-controlled trial of the antiepileptic drug lamotrigine in patients with the Lennox-Gastaut syndrome. Eligible patients had more than one type of predominantly generalized seizure, including tonic-clonic, atonic, tonic, and major myoclonic, and had seizures on average at least every other day. After a 4-week base-line period in which all participants received placebo, we randomly assigned 169 patients (age range, 3 to 25 years) to 16 weeks of lamotrigine (n= 79) or placebo (n=90) in addition to their other antiepileptic drugs. RESULTS: The median frequency of all major seizures changed from base-line levels of 16.4 and 13.5 per week in the lamotrigine and placebo groups, respectively, to 9.9 and 14.2 per week after 16 weeks of treatment (P=0.002). Thirty-three percent of the patients in the lamotrigine group and 16 percent of those in the placebo group had a reduction of at least 50 percent in the frequency of seizures (P= 0.01). There were no significant differences between groups in the incidence of adverse events, except for colds or viral illnesses, which was more common in the lamotrigine group (P=0.05). CONCLUSIONS: Lamotrigine was an effective and well-tolerated treatment for seizures associated with the Lennox-Gastaut syndrome.

Ontogeny of gonadotropin, testosterone, and inhibin secretion in normal boys through puberty based on overnight serial sampling.

To investigate hormonal changes occurring in male puberty, we measured LH, FSH, testosterone, and alpha-inhibin immunoactivity in serum samples drawn every 10 min for 8 h (2100-0500 h) from each of 50 normal prepubertal and pubertal boys, aged 8.4-18.8 yr. We measured gonadotropins with ultrasensitive immunofluorometric assays, and testosterone and alpha-inhibin with RIAs. Unlike previous studies, which indexed pubertal development with Tanner stages, we used testicular volume, a more finely graduated indicator of development, to reveal patterns that were obscured when subjects were grouped by Tanner stage. The overnight mean concentration of each hormone increased with testis volume, but the rate of increase on a logarithmic scale slowed as testes grew. Log LH rose precipitously in the late prepubertal and early pubertal periods and plateaued during mid- and late puberty. Based on fitted regression curves, LH increased about 20-fold (from 0.11 IU/L) between testis volumes of 1 and 10 mL, but only an additional 1.5-fold by 30 mL. The developmental trajectory of log testosterone was like that of log LH, but rose less steeply early in puberty. From 0.14 micrograms/L at a testis volume of 1 mL, testosterone increased about 8.5-fold by 10 mL and an additional 3-fold by 30 mL. In contrast, logarithms of overnight mean FSH and alpha-inhibin concentrations rose at a more nearly constant rate throughout puberty. From 0.62 IU/L at a testis volume of 1 mL, the FSH concentration doubled by 10 mL and increased an additional 1.7-fold by 30 mL. From 270 ng/L at a testis volume of 1 mL, inhibin increased 1.5-fold by 10 mL and an additional 1.3-fold by 30 mL. Overnight pulse amplitudes exhibited developmental trajectories similar to those of the corresponding overnight mean concentrations. The number of LH and testosterone pulses during the sampling period averaged 2.2 and 2.1, respectively, at Tanner stage 1 and increased to 4.5 and 3.2, respectively, at Tanner stage 5. The number of FSH and inhibin pulses remained constant throughout puberty, averaging 3.3 and 3.5, respectively. Pairwise correlations among hormone concentrations were strong, reflecting common increasing trends through puberty; however, after accounting for developmental trends, FSH, LH, and testosterone concentrations remained correlated, whereas inhibin was uncorrelated with each of the other three hormones. Measuring gonadotropins with ultrasensitive assays and analyzing the results on a logarithmic scale as a function of testis volume made clear the dramatic hormonal changes that begin before the clinical changes of puberty.

Multiple hormone deficiencies in children with hemochromatosis.

Patients with thalassemia major require multiple blood transfusions leading to hemochromatosis. These patients often have pubertal delay and growth failure, the etiology of which has not been fully elucidated. We performed an extensive endocrine evaluation which included measurements of spontaneous and stimulated levels of gonadotropins, GH, thyroid hormone, and adrenal hormones in 17 patients between the ages of 12 and 18 yr with hemochromatosis receiving desferoxamine therapy. All of the 17 patients had at least one endocrine abnormality, and 12 had more than one abnormality. Abnormalities of the hypothalamic-pituitary-gonadal axis were the most common. Six patients had clinical evidence of delayed puberty with spontaneous and stimulated gonadotropin and sex steroid levels appropriate for their delayed pubertal stage. All 14 children in puberty LH pulsatility index below the mean for pubertal stage compared to normal children. Six of the 14 had LH pulsatility index more than 2 SD below the mean for pubertal stage. This may be an indicator of abnormal pituitary function. Six patients failed either the provocative GH tests (peak GH < 7 micrograms/L) or had a mean spontaneous GH less than 1 microgram/L. The 4 patients who failed provocative tests had growth velocities more than 2 SD below the mean for bone age. Three patients had evidence of primary hypothyroidism. We conclude that all patients with hemochromatosis need periodic careful endocrine evaluations because the incidence of endocrine dysfunction is substantial and they may benefit from hormonal therapy.

Adult height in precocious puberty after long-term treatment with deslorelin.

Precocious puberty often leads to short adult height. Since the introduction of luteinizing hormone-releasing hormone (LHRH) agonist treatment for LHRH-dependent precocious hormone (LHRH) agonist treatment for LHRH-dependent precocious puberty in 1979, several reports have shown increased predicted height among LHRH agonist-treated children. To determine whether the LHRH agonist deslorelin can normalize the adult height of children with precocious puberty, we are conducting a long-term pilot study involving 161 children. This report describes the first 44 children to have attained final or proximate adult height. These children were 7.1 +/- 1.2 (mean +/- SD) yr old (bone age 11.8 +/- 1.5 yr) and had been in puberty for 3.1 +/- 0.3 yr at the start of treatment. They were treated with deslorelin (4 micrograms/kg/day sc) for 4.1 +/- 1.3 yr and had been withdrawn from treatment for an average of 2.4 yr at the time of this study (age 13.6 +/- 0.9 yr). Fourteen of the 44 children, who had grown less than 0.5 cm during the previous year, were considered to have attained adult height. The other 30 children had achieved 98.6% of predicted mature height (Bayley-Pinneau method) and were considered to be at proximate adult height. The final or proximate adult height of these 44 children averaged -1.1 SD compared to the adult height of the normal population. This height was significantly greater than the pretreatment height (-1.1 vs. -2.0 SD, P less than 0.01), but significantly less than both the predicted height at the end of treatment (-1.1 vs. -0.5 SD, P less than 0.01) and the target height derived from the mean height of the parents adjusted for the sex of the child (-1.1 vs. 0.1 SD, P less than 0.01). The observation that the Bayley-Pinneau height prediction at the end of treatment overestimated the actual adult height emphasizes the importance of using final height data to assess the ultimate impact of LHRH agonist treatment. It also indicates the need for caution when predicting the adult height of children who are still receiving treatment. We conclude that deslorelin has improved the adult height of these patients but has not fully restored height to the patients' genetic potential. We hypothesize that further improvement will be seen in patients who are treated with less delay and at a younger bone age.

Luteinizing hormone-releasing hormone (LHRH)-independent precocious puberty unresponsive to LHRH agonist therapy in two girls lacking features of the McCune-Albright syndrome.

Two girls with precocious puberty (chronological age, 1 and 4 yr; bone age, 3 and 6 yr, respectively) were initially given the diagnosis of idiopathic, central precocious puberty and treated with the LHRH agonist deslorelin (D-Trp6-Pro9-NEt-LHRH) for 5 yr. Unlike other girls with central precocious puberty, both had persistently elevated rates of growth and bone maturation, and both menstruated during therapy. One girl had episodic ovarian enlargement and markedly elevated serum estradiol levels due to recurrent unilateral ovarian cysts. Although the bone and skin manifestations of McCune-Albright syndrome were absent, we hypothesize that the underlying defect of McCune-Albright syndrome was expressed in the ovaries, but not in the skin or bones, of these two girls. One of these girls appeared to benefit from the aromatase inhibitor testolactone, which is effective in suppressing precocious puberty in girls with the McCune-Albright syndrome.

A novel testis-stimulating factor in familial male precocious puberty.

BACKGROUND: Familial male precocious puberty is a gonadotropin-independent form of precocious puberty that occurs only in males. The cause of the disorder is unknown. To examine the hypothesis that the plasma of boys with familial male precocious puberty contains a novel stimulator of testicular testosterone production, we developed a bioassay using adult male cynomolgus monkeys. METHODS: We collected plasma from 12 boys with familial male precocious puberty, 7 normal prepubertal boys of similar ages and with similar plasma gonadotropin levels, and 1 boy with hypogonadotropic hypogonadism and infused it into the testicular artery of adult male cynomolgus monkeys that had been pretreated with gonadotropin-releasing-hormone antagonist to inhibit the endogenous secretion of gonadotropins. Testicular venous effluent was collected at 15-minute intervals for 3 or 5 hours for the measurement of testosterone. RESULTS: The mean (+/- SE) peak testosterone response, as compared with base line, was significantly greater in the monkeys infused with plasma from the 12 boys with familial male precocious puberty than in the monkeys infused with plasma from the 7 normal prepubertal boys and the boy with hypogonadotropic hypogonadism (385 +/- 51 vs. 184 +/- 25 percent, P less than 0.005) in the three-hour studies. Plasma from 92 percent of the boys with familial male precocious puberty and 12.5 percent of the normal prepubertal boys stimulated a response greater than 195 percent of base-line values. In the animals studied for five hours after receiving a second dose of antagonist, the mean peak testosterone response, as compared with base line, was significantly greater in the monkeys infused with plasma from three boys with familial male precocious puberty than in the monkeys infused with plasma from three normal prepubertal boys (363 +/- 81 vs. 115 +/- 6 percent, P less than 0.01). The mean area under the testosterone-response curve was significantly larger in the monkeys infused with plasma from the boys with familial male precocious puberty in the five-hour studies (154 +/- 34 vs. -58 +/- 10 percent, P less than 0.005), but not in the three-hour studies. CONCLUSIONS: These findings support the presence of a circulating testis-stimulating factor in the plasma of boys with familial male precocious puberty. The production of such a factor would explain the biologic nature of the disorder.

Low growth hormone levels are related to increased body mass index and do not reflect impaired growth in luteinizing hormone-releasing hormone agonist-treated children with precocious puberty.

To test the hypothesis that GH deficiency might explain the low growth velocity of some LHRH agonist (LHRHa)-treated children with central precocious puberty, we measured stimulated (n = 81) and spontaneous (n = 32) GH levels during or after LHRHa treatment. GH stimulation tests in the children who were receiving LHRHa treatment were performed after 2 days of ethinyl estradiol administration. Thirty-one of 81 children (38%) who underwent GH stimulation tests had subnormal responses (less than or equal to 7 micrograms/L) to all tests administered (at least 2 stimuli), including 22 of 67 (33%) who had precocious puberty that was idiopathic or associated with hypothalamic hamartoma. Eleven of 32 children (34%) who underwent measurement of the mean nighttime spontaneous GH level had levels below the normal range for prepubertal children (less than 1.2 microgram/L). Despite the high incidence of subnormal GH levels, there appeared to be no relationship between the GH levels of these children and their growth characteristics. The height, growth velocity, bone maturation rate, predicted height, and insulin-like growth factor-I levels were not different between the children with low GH levels and the children with normal GH levels. Conversely, the GH levels were not different between the children with subnormal growth rates and the children with normal growth rates. Thus, variation in the growth rates of these LHRHa-treated children with central precocious puberty could not be explained by variation in the stimulated or spontaneous secretion of GH. In attempting to understand the high incidence of low GH levels in children with precocious puberty, we examined the relationship between GH level and body mass index (BMI). Both the stimulated (r = -0.33; P less than 0.002) and the spontaneous (r = -0.61; P less than 0.0002) GH levels were inversely related to BMI. Moreover, the children with precocious puberty as a group had significantly elevated BMI [1.2 +/- 0.1 (+/- SE) SD units] compared to normal children of the same age (P less than 0.0001). Thus, increased body mass may explain the high incidence of subnormal GH levels in these patients, and normative GH levels adjusted for body mass are needed before it can be concluded that the apparently subnormal GH levels in LHRHa-treated children with precocious puberty are in fact low.

Hypothyroidism and deficiency of the nocturnal thyrotropin surge in children with hypothalamic-pituitary disorders.

The circadian pattern of serum TSH in normal children, aged 5-18 yr, is characterized by a nocturnal surge and is presumably related in some way to a biological clock within the central nervous system. To look for patients deficient in the nocturnal TSH surge, we studied 52 children with hypothalamic-pituitary disorders. Thirteen of the children were hypothyroid, as judged by subnormal serum free T4 (FT4). The hypothyroid patients had a mean nocturnal TSH surge of 22% (range, -30% to +114%), significantly less than that of normal controls (mean, 124%; 95% confidence limits, 47-300%; n = 96; P less than 0.01). Only 1 of the hypothyroid children had a value for the nocturnal TSH surge (114%) that was within the normal range. Nineteen of the 52 patients with hypothalamic-pituitary disorders had subnormal nocturnal TSH surges; their mean iodothyronine values were significantly less than those of the 33 patients with normal surges [total T4, 73 +/- 4 (mean +/- SE) vs. 109 +/- 3 nmol/L (P less than 0.01); FT4, 13 +/- 1.0 vs. 19 +/- 0.5 pmol/L (P less than 0.01)]. These data demonstrate a clear association of a deficient nocturnal TSH surge and low iodothyronine concentration in children with hypothalamic-pituitary disorders. We performed both TRH tests and nocturnal TSH surge tests in 11 of the children with central hypothyroidism; TRH was abnormal in only 2, while the nocturnal surge test was abnormal in 10 of the 11. We suggest that the nocturnal surge of TSH is important for maintenance of thyroid function and conclude that the nocturnal TSH surge is a much more sensitive test than the TSH response to TRH for the diagnosis of central hypothyroidism.