Male pattern baldness and coronary heart disease: the Physicians' Health Study

The adapted classification of male pattern hair loss improves reliability

BACKGROUND

The Hamilton-Norwood classification (HNC) is used to assess the severity of pattern hair loss (PHL). Conflicting associations between PHL and cardiovascular disease (CVD) have been reported from studies that used different methods to assess alopecia severity. No classification including the HNC has been validated for population studies. We aimed to simplify the HNC, produce the adapted HNC and test its reliability for use in population studies.

METHODS

Identifying vertex alopecia as distinct allowed for a simpler alignment of alopecia figures where scores 4V and 5V in the adapted HNC replace IV and V in the original HNC. The two classifications were to be used by twelve of our staff (secretaries, nurses, dermatology trainees and dermatologists) to evaluate 16 men with PHL. Observer agreement was estimated using intraclass correlation coefficient (ICC) and a percentage method duplicated from the recent basic and specific (BASP) classification.

RESULTS

The ICC improved with the adapted HNC when assessed by both the nurses/secretaries (from 0.47 to 0.61) and dermatology residents/consultants (from 0.68 to 0.76). Agreement using the BASP percentage method for dermatologists was 62-69% for the original and 93-100% for the adapted HNC.

CONCLUSIONS

The adapted HNC increased reliability at various staff levels, making it suitable for epidemiological studies; its use in future studies could help elucidate the association between PHL and CVD.

The differences between aromatizable and non-aromatizable androgens in relation to body composition and metabolic syndrome risk factors in men

The relationships between the parameters of metabolic syndrome and non-aromatizable metabolites of testosterone have been discussed in literature. Some papers describe these metabolites as one of the possible causes of male-type obesity. On the contrary, other studies show a protective influence of dihydrotestosterone on visceral obesity. The aim of this study to analyse the relationship between anthropometric parameters, lipid spectrum, glycemia and the level of endogenous testosterone and dihydrotestosterone, and to compare the effects of these androgens. Our population-based study involved 232 healthy men ranging from 20 to 78 years with BMI 18 to 39 kg/m(2). Serum testosterone, dihydrotestosterone and sex hormone binding globulin SHBG levels, lipid spectrum, glucose metabolism parameters were measured and the oral glucose tolerance test was carried out in all subjects. Their anthropometric parameters (weight, height, waist, hips, waist-to-hip ratio, 14 skin folds) and body composition parameters were determined and calculated by the Antropo program. Multiple regression analysis showed a correlation between hormonal levels, esp. of testosterone and dihydrotestosterone, and the anthropometric data, lipid spectrum and parameters of glucose regulation. Low testosterone and/or dihydrotestosterone was correlated to a higher body-mass index, fat content, waist diameter, total-, HDL-, LDL-cholesterol and triglycerides, fasting glucose, insulin resistance and lower muscle and bone mass. In addition, statistical analysis using multivariate regression with reduction in dimensionality did not discover any striking difference between aromatizable and non-aromatizable androgens in their association to lipid and glucose metabolism parameters in healthy, normosthenic men. In conclusion, the association of endogenous testosterone and dihydrotestosterone to anthropometric data, lipid spectrum and insulin sensitivity are of the same quality; however, the effect of the circulating levels of dihydrotestosterone is quantitatively smaller.

Gender-specific association of androgenetic alopecia with metabolic syndrome in a middle-aged Korean population

BACKGROUND

Although several previous studies have investigated the association between metabolic syndrome (MetS) and androgenetic alopecia (AGA), the study results have been inconsistent.

OBJECTIVES

The aim of this study was to investigate the relationship between the presence of MetS and AGA according to gender in a middle-aged Korean population.

METHODS

A population-based cross-sectional study was conducted on a sample from the Korean Genome Epidemiology Study. In total, 3408 subjects (1707 men and 1701 women) were enrolled between January 2008 and February 2010. The Norwood classification for men and Ludwig classification for women were used for assessment of the degree of hair loss. Information on components of MetS together with other possible risk factors was collected.

RESULTS

In men, the risk of having Norwood type IV or greater was not increased for subjects with MetS compared with those without MetS. In women, the risk of having Ludwig type I or greater was significantly increased for subjects with MetS compared with those without MetS after controlling for age and smoking status (OR 1.68, 95% CI 1.14-2.48; P=0.01). Similar results were also observed for the number of fulfilled components of MetS [odds ratio (OR) 1.38, 95% confidence interval (CI) 1.00-1.91; P<0.05]. When each component of MetS was considered individually, associations between AGA and all five components of MetS (waist circumference, triglycerides, high-density lipoprotein-C, blood glucose, and blood pressure) were not statistically significant. When multiple regression was used to adjust for age, family history and smoking, there was no significant association between the prevalence of MetS and moderate to severe AGA in the male group. On the contrary, a statistically significant positive association was noted between the prevalence of MetS and AGA in the female group.

CONCLUSIONS

Our analysis of AGA and the prevalence of MetS in a large population-based cohort demonstrated quite different findings compared with previous reports. The different results according to gender suggest that there may be different mechanisms that are yet to be defined between male and female AGA.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Our systematic review has demonstrated that antioxidant supplements may increase mortality. We have now updated this review.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements for prevention of mortality in adults.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to February 2011. We scanned bibliographies of relevant publications and asked pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Random-effects and fixed-effect model meta-analyses were conducted. Risk of bias was considered in order to minimise the risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors. Random-effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Seventy-eight randomised trials with 296,707 participants were included. Fifty-six trials including 244,056 participants had low risk of bias. Twenty-six trials included 215,900 healthy participants. Fifty-two trials included 80,807 participants with various diseases in a stable phase. The mean age was 63 years (range 18 to 103 years). The mean proportion of women was 46%. Of the 78 trials, 46 used the parallel-group design, 30 the factorial design, and 2 the cross-over design. All antioxidants were administered orally, either alone or in combination with vitamins, minerals, or other interventions. The duration of supplementation varied from 28 days to 12 years (mean duration 3 years; median duration 2 years). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects model meta-analysis (21,484 dead/183,749 (11.7%) versus 11,479 dead/112,958 (10.2%); 78 trials, relative risk (RR) 1.02, 95% confidence interval (CI) 0.98 to 1.05) but significantly increased mortality in a fixed-effect model (RR 1.03, 95% CI 1.01 to 1.05). Heterogeneity was low with an I(2)- of 12%. In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. Meta-regression analysis did not find a significant difference in the estimated intervention effect in the primary prevention and the secondary prevention trials. In the 56 trials with a low risk of bias, the antioxidant supplements significantly increased mortality (18,833 dead/146,320 (12.9%) versus 10,320 dead/97,736 (10.6%); RR 1.04, 95% CI 1.01 to 1.07). This effect was confirmed by trial sequential analysis. Excluding factorial trials with potential confounding showed that 38 trials with low risk of bias demonstrated a significant increase in mortality (2822 dead/26,903 (10.5%) versus 2473 dead/26,052 (9.5%); RR 1.10, 95% CI 1.05 to 1.15). In trials with low risk of bias, beta-carotene (13,202 dead/96,003 (13.8%) versus 8556 dead/77,003 (11.1%); 26 trials, RR 1.05, 95% CI 1.01 to 1.09) and vitamin E (11,689 dead/97,523 (12.0%) versus 7561 dead/73,721 (10.3%); 46 trials, RR 1.03, 95% CI 1.00 to 1.05) significantly increased mortality, whereas vitamin A (3444 dead/24,596 (14.0%) versus 2249 dead/16,548 (13.6%); 12 trials, RR 1.07, 95% CI 0.97 to 1.18), vitamin C (3637 dead/36,659 (9.9%) versus 2717 dead/29,283 (9.3%); 29 trials, RR 1.02, 95% CI 0.98 to 1.07), and selenium (2670 dead/39,779 (6.7%) versus 1468 dead/22,961 (6.4%); 17 trials, RR 0.97, 95% CI 0.91 to 1.03) did not significantly affect mortality. In univariate meta-regression analysis, the dose of vitamin A was significantly associated with increased mortality (RR 1.0006, 95% CI 1.0002 to 1.001, P = 0.002).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.

Sex hormone-binding globulin and risk of hyperglycemia in patients with androgenetic alopecia

BACKGROUND

Low circulating levels of sex hormone-binding globulin (SHBG) are a strong predictor of the risk of type 2 diabetes. Androgenetic alopecia (AGA) has been related to an increase in cardiovascular risk, but the mechanism of this association has not been elucidated. AGA can be associated with low levels of SHBG and insulin resistance, which could be related to hyperglycemia and type 2 diabetes.

OBJECTIVE

The objective of this study was to evaluate SHBG and blood glucose levels in men and women with early-onset AGA and control subjects to determine whether low levels of SHBG are associated with hyperglycemia.

METHODS

This case-control study included 240 patients consecutively admitted to the outpatient clinic (Dermatology Department of San Cecilio University Hospital, Granada, Spain), 120 with early-onset AGA (60 men and 60 women) and 120 control subjects (60 men and 60 women) with skin diseases other than alopecia.

RESULTS

Of patients with AGA, 39.1% presented with hyperglycemia (>110 mg/dL) versus 12.5% of controls (P < 0.0001). AGA patients with hyperglycemia or diabetes presented lower significant levels of SHBG than alopecic patients without hyperglycemia or type 2 diabetes, respectively. Patients with AGA and hyperglycemia presented significantly lower levels of SHBG than controls with hyperglycemia (22.3 vs 39.4 nmol/L for AGA patients and controls, respectively, P = .004). No significant differences in SHBG levels were noticed between patients and controls without hyperglycemia. Binary logistic regression showed a strong association between lower SHBG levels and glucose levels greater than 110 mg/dL in patients with AGA even after additional adjustment for sex, abdominal obesity, and free testosterone (odds ratio = 3.35; 95% confidence interval = 1.9-5.7; P < .001).

LIMITATIONS

The study of a wider sample of AGA patients would confirm these findings and would permit analysis of the pathogenic mechanisms underlying the increase in cardiovascular risk in patients with AGA.

CONCLUSION

An association between early-onset AGA, hyperglycemia/diabetes, and low levels of SHBG was observed in the current study. Low levels of SHBG could be a marker of insulin resistance and hyperglycemia/diabetes in patients with AGA.

The Role of Non-Aromatizable Testosterone Metabolite in Metabolic Pathways

Dihydrotestosterone (DHT) originates via irreversible reduction of testosterone by catalytic activity of 5α-reductase enzyme and it is demonstratively the most effective androgen. Androgens influence adipose tissue in men either directly by stimulation of the androgen receptor or indirectly, after aromatization, by acting at the estrogen receptor. DHT as a non-aromatizable androgen could be responsible for a male type fat distribution. The theory of non-aromatizable androgens as a potential cause of a male type obesity development has been studied intensively. However, physiological levels of DHT inhibit growth of mature adipocytes. In animal models, substitution of DHT in males after gonadectomy has a positive effect on body composition as a testosterone therapy. Thus, DHT within physiological range positively influences body composition. However, there are pathological conditions with an abundance of DHT, e.g. androgenic alopecia and benign prostatic hyperplasia. These diseases are considered as risk factors for development of metabolic syndrome or atherosclerosis. In obese people, DHT metabolism in adipose tissue is altered. Local abundance of non-aromatizable androgen has a negative effect on adipose tissue and it could be involved in pathogenesis of metabolic and cardiovascular diseases. Increased DHT levels, compared to physiological levels, have negative effect on development of cardiovascular diseases. Difference between the effect of physiological and increased level brings about certain paradox.

Androgenetic alopecia and cardiovascular risk factors in men and women: a comparative study

BACKGROUND

Numerous studies in recent decades have associated male androgenetic alopecia (AGA) with the risk of cardiovascular disease. However, only 3 studies have addressed this association in female patients. Most studies considered the risk of myocardial infarction or mortality as a result of heart disease, without analyzing cardiovascular risk factors.

OBJECTIVES

The objectives of this study were to analyze the presence of cardiovascular risk factors included in the Adult Treatment Panel-III criteria for metabolic syndrome, the prevalence of carotid atheromatosis, hormonal (aldosterone, insulin, testosterone, and sex hormone-binding globulin) factors, and acute phase reactant (C-reactive protein, fibrinogen, D-dimers, erythrocyte sedimentation rate) variables in male and female patients with AGA and in a control group, and to analyze differences among the groups.

METHODS

This case-control study included 154 participants, 77 with early-onset AGA (40 male and 37 female) and 77 healthy control subjects (40 male and 37 female) from the dermatology department at a university hospital in Granada, Spain.

RESULTS

Metabolic syndrome was diagnosed in 60% of male patients with AGA (odds ratio [OR] = 10.5, 95% confidence interval [CI] 3.3-32.5), 48.6% of female patients with AGA (OR = 10.73, 95% CI 2.7-41.2), 12.5% of male control subjects, and 8.1% of female control subjects (P < .0001). Atheromatous plaques were observed in 32.5% of male patients with AGA (OR = 5.93, 95% CI 1.5-22.9) versus 7.5% of male control subjects (P = .005) and 27% of female patients with AGA (OR = 4.19, 95% CI 1.05-16.7) versus 8.1% of female control subjects (P = .032). Aldosterone and insulin levels were significantly higher in the male and female patients with AGA versus their respective control subjects. Mean values of fibrinogen were significantly higher in male patients with AGA, whereas values of fibrogen, C-reactive protein, and D-dimers were significantly higher in female patients with AGA versus their respective control subjects.

LIMITATIONS

The study of a wider sample of patients with AGA would confirm these findings and allow a detailed analysis of the above factors as a function of the degree of alopecia or between menopausal and premenopausal women.

CONCLUSION

The determination of metabolic syndrome and ultrasound study of the carotid arteries may be useful screening methods to detect risk of developing cardiovascular disease in male and female patients with early-onset AGA and signal a potential opportunity for early preventive treatment.

Association of androgenetic alopecia with metabolic syndrome in men: a community-based survey

BACKGROUND

Several previous studies have investigated the association between factors related to metabolic syndrome, which is known to increase the risk of type 2 diabetes mellitus and cardiovascular disease, and androgenetic alopecia (AGA). However, the results of these studies have been inconsistent.

OBJECTIVES

To determine if there is an association between metabolic syndrome and AGA after adjustment for potential confounders.

METHODS

A population-based cross-sectional survey was conducted in Tainan, Taiwan. A total of 740 subjects aged 40-91 years participated in the survey between April and June 2005. The Norwood classification was used to assess the degree of hair loss. Information on components of metabolic syndrome together with other possible risk factors was collected.

RESULTS

A statistically significant association was found between AGA and the presence of metabolic syndrome [odds ratio (OR) 1.67, 95% confidence interval (CI) 1.01-2.74] as well as between AGA and the number of fulfilled metabolic syndrome components (OR 1.21, 95% CI 1.03-1.42) after controlling for age, family history of AGA and smoking status. Among metabolic syndrome components, high-density lipoprotein cholesterol (HDL-C) (OR 2.36, 95% CI 1.41-3.95; P = 0.001) was revealed as the most important factor associated with AGA.

CONCLUSIONS

Our population-based study found a significant association between AGA and metabolic syndrome; among the components of metabolic syndrome, HDL-C was found to be of particular importance. This finding may have significant implications for the identification of metabolic syndrome in patients with moderate or severe AGA. Early intervention for metabolic syndrome is critical to reduce the risk and complications of cardiovascular disease and type 2 diabetes mellitus later in life.

Genetik der androgenetischen Alopezie

Die androgenetische Alopezie (AGA, erblich- bzw. hormonbedingter Haarausfall [MIM 109200; MIM 300710; MIM 612421]) ist die häufigste Form des Haarverlusts beim Menschen, wobei die Prävalenz stark altersabhängig ist. Im Alter von über 70 Jahren sind über 80% der europäischen Männer betroffen, bei Frauen liegt die AGA-Häufigkeit mit 30–40% deutlich niedriger. Die AGA führt, v. a. bei betroffenen Frauen, zu einer erheblichen psychologischen Belastung und entfaltet dabei Krankheitswert. Der Haarverlust geht auf einen veränderten Haarzyklus und eine Miniaturisierung des Haarfollikels zurück. Die Pathogenese ist androgenabhängig, und die genetische Anlage ist wesentliche Voraussetzung für den Phänotyp. In mehreren Studien konnten der Androgenrezeptor-/Ektodysplasin-A2-Rezeptor(EDA2R)-Locus auf dem X-Chromosom als stärkster beitragender Faktor und durch genomweite Assoziationsuntersuchungen ein weiterer Locus auf Chromosom 20p11 identifiziert werden. Das zum Assoziationssignal nächstgelegene in der Kopfhaut exprimierte Gen ist „paired box 1“ (PAX1). Zwischen PAX1 und dem Androgensignalweg gibt es keine offensichtliche Verbindung, jedoch sind die dem Assoziationssignal auf Chromosom 20p11 zugrunde liegenden pathophysiologischen Prozesse noch nicht geklärt. Bis heute ermöglichen die zur Verfügung stehenden medikamentösen Therapien der AGA bestenfalls ein Aufhalten des Haarverlusts. Mit der Identifizierung der AGA-assoziierten Gene und der Aufklärung ihrer Funktionen wird man die biologischen Ursachen der AGA schrittweise erschließen. Damit ist die Hoffnung auf die Entwicklung neuer Therapien verbunden.

Androgens and hair loss

PURPOSE OF REVIEW

Androgenetic alopecia (AGA) or male pattern hair loss is a very common condition that has a significant psychosocial impact for patients. Many advances in the pathogenesis and treatment of AGA have been discovered recently. We discuss the pathogenesis and treatment of AGA.

RECENT FINDINGS

Wide genome analysis showed an association of AGA and chromosome 20pll in addition to androgen-receptor gene. Also, a locus on chromosome 3q26 was found to have a linkage with AGA. Dutasteride has been shown to be more effective than finasteride in the treatment of AGA but is not yet a recommended therapy. In an in-vitro study, a new topical liposomal finasteride formulation showed more than five-fold higher deposition of drug in skin than the corresponding plain drug solution.

SUMMARY

These recent developments in the field of AGA hold some promise and may play a role in the future management.

Associations among hair loss, oral sulfur-containing gases, and gastrointestinal and metabolic linked diseases in Japanese elderly men: pilot study

BACKGROUND

Male pattern baldness (MPB), an observable trait, has been reported to be associated with various diseases, such as prostate cancer and cardiovascular disease. Oral sulfur-containing gases have also been suggested to be useful as markers of systemic health condition. However, there are no known reports regarding the associations among MPB, and oral sulfur-containing gases, and systemic health conditions in males.

METHODS

We studied 170 male subjects aged either 60 or 65 years old. The degree of MPB was assessed using the Norwood-Hamilton Baldness scale. Oral sulfur-containing gases were measured using a compact-designed device. All subjects completed physical and laboratory blood examinations, a face-to-face medical questionnaire, and an oral examination.

RESULTS

There were significant differences between the levels of CH3SCH3 and baldness patterns, independent of age. When we analyzed whether the association was linked to systemic health condition, a strong significant association was observed between the level of CH3SCH3 and severe MPB in subjects with gastrointestinal diseases, hypertension, and hypercholesterolemia.

CONCLUSION

These results suggest that MPB is associated with the level of CH3SCH3, a sulfur-containing gas that causes oral malodor, in elderly Japanese males. Further, the association was intensified by the existence of gastrointestinal tract and metabolic disorders.

Is androgenetic alopecia a risk for atherosclerosis?

BACKGROUND

Several studies have demonstrated the presence of an association between androgenetic alopecia (AGA) and cardiovascular disease. The aim of this study was to evaluate subclinical atherosclerosis in patients with AGA and healthy controls by the incorporation of carotid intima-media thickness (IMT) and high-sensitive C-reactive protein (hs-CRP) along with echocardiography (ECHO) and exercise electrocardiography (ExECG).

METHODS

We performed a case-control study in 50 male patients with AGA and 31 age-matched healthy male controls with normal hair status. Both the AGA patients and controls with a history of diabetes mellitus, cigarette smoking, hypertension, cardiovascular or cerebrovascular disease, and renal failure were excluded. AGA was classified according to the Hamilton-Norwood scale. Serum lipids, serum hs-CRP, total testosterone, and dehydroepiandrosterone sulphate were examined in all study subjects. Carotid ultrasonography was used to measure the IMT of the common carotid arteries (CCA). ECHO and ExECG were performed in all subjects.

RESULTS

IMT of the CCA was found to be significantly higher in patients with severe vertex pattern AGA when compared to patients with other patterns of AGA and healthy controls (P < 0.05). Hs-CRP in patients with any group of AGA was not significantly different from those healthy controls (P > 0.05). ECHO showed that cardiac structural and functional measures were in normal ranges. ExECG was also normal in all subjects.

CONCLUSION

Severe vertex pattern AGA should be considered to have an increased risk of subclinical atherosclerosis. For this reason, CCA IMT measurement can be recommended as a non-invasive and early diagnostic method.

Antioxidant supplements for preventing gastrointestinal cancers

BACKGROUND

Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements in preventing gastrointestinal cancers.

SEARCH STRATEGY

We identified trials through the trials registers of the four Cochrane Review Groups on gastrointestinal diseases, The Cochrane Central Register of Controlled Trials in The Cochrane Library (Issue 2, 2007), MEDLINE, EMBASE, LILACS, SCI-EXPANDED, and The Chinese Biomedical Database from inception to October 2007. We scanned reference lists and contacted pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing antioxidant supplements to placebo/no intervention examining occurrence of gastrointestinal cancers.

DATA COLLECTION AND ANALYSIS

Two authors (GB and DN) independently selected trials for inclusion and extracted data. Outcome measures were gastrointestinal cancers, overall mortality, and adverse effects. Outcomes were reported as relative risks (RR) with 95% confidence interval (CI) based on random-effects and fixed-effect model meta-analysis. Meta-regression assessed the effect of covariates across the trials.

MAIN RESULTS

We identified 20 randomised trials (211,818 participants), assessing beta-carotene (12 trials), vitamin A (4 trials), vitamin C (8 trials), vitamin E (10 trials), and selenium (9 trials). Trials quality was generally high. Heterogeneity was low to moderate. Antioxidant supplements were without significant effects on gastrointestinal cancers (RR 0.94, 95% CI 0.83 to 1.06). However, there was significant heterogeneity (I(2) = 54.0%, P = 0.003). The heterogeneity may have been explained by bias risk (low-bias risk trials RR 1.04, 95% CI 0.96 to 1.13 compared to high-bias risk trials RR 0.59, 95% CI 0.43 to 0.80; test of interaction P < 0.0005), and type of antioxidant supplement (beta-carotene potentially increasing and selenium potentially decreasing cancer risk). The antioxidant supplements had no significant effects on mortality in a random-effects model meta-analysis (RR 1.02, 95% CI 0.97 to 1.07, I(2) = 53.5%), but significantly increased mortality in a fixed-effect model meta-analysis (RR 1.04, 95% CI 1.02 to 1.07). Beta-carotene in combination with vitamin A (RR 1.16, 95% CI 1.09 to 1.23) and vitamin E (RR 1.06, 95% CI 1.02 to 1.11) significantly increased mortality. Increased yellowing of the skin and belching were non-serious adverse effects of beta-carotene. In five trials (four with high risk of bias), selenium seemed to show significant beneficial effect on gastrointestinal cancer occurrence (RR 0.59, 95% CI 0.46 to 0.75, I(2) = 0%).

AUTHORS' CONCLUSIONS

We could not find convincing evidence that antioxidant supplements prevent gastrointestinal cancers. On the contrary, antioxidant supplements seem to increase overall mortality. The potential cancer preventive effect of selenium should be tested in adequately conducted randomised trials.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Animal and physiological research as well as observational studies suggest that antioxidant supplements may improve survival.

OBJECTIVES

To assess the effect of antioxidant supplements on mortality in primary or secondary prevention randomised clinical trials.

SEARCH STRATEGY

We searched The Cochrane Library (Issue 3, 2005), MEDLINE (1966 to October 2005), EMBASE (1985 to October 2005), and the Science Citation Index Expanded (1945 to October 2005). We scanned bibliographies of relevant publications and wrote to pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. Included participants were either healthy (primary prevention trials) or had any disease (secondary prevention trials).

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Trials with adequate randomisation, blinding, and follow-up were classified as having a low risk of bias. Random-effects and fixed-effect meta-analyses were performed. Random-effects meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Sixty-seven randomised trials with 232,550 participants were included. Forty-seven trials including 180,938 participants had low risk of bias. Twenty-one trials included 164,439 healthy participants. Forty-six trials included 68111 participants with various diseases (gastrointestinal, cardiovascular, neurological, ocular, dermatological, rheumatoid, renal, endocrinological, or unspecified). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects meta-analysis (relative risk [RR] 1.02, 95% confidence interval [CI] 0.99 to 1.06), but significantly increased mortality in a fixed-effect model (RR 1.04, 95% CI 1.02 to 1.06). In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. In the trials with a low risk of bias, the antioxidant supplements significantly increased mortality (RR 1.05, 95% CI 1.02 to 1.08). When the different antioxidants were assessed separately, analyses including trials with a low risk of bias and excluding selenium trials found significantly increased mortality by vitamin A (RR 1.16, 95% CI 1.10 to 1.24), beta-carotene (RR 1.07, 95% CI 1.02 to 1.11), and vitamin E (RR 1.04, 95% CI 1.01 to 1.07), but no significant detrimental effect of vitamin C (RR 1.06, 95% CI 0.94 to 1.20). Low-bias risk trials on selenium found no significant effect on mortality (RR 0.91, 95% CI 0.76 to 1.09).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Vitamin A, beta-carotene, and vitamin E may increase mortality. Future randomised trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects. Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing.

Genome-wide scan and fine-mapping linkage study of androgenetic alopecia reveals a locus on chromosome 3q26

Androgenetic alopecia (AGA, male pattern baldness) is the most common form of hair loss. The origin of AGA is genetic, with the X chromosome located androgen receptor gene (AR) being the only risk gene identified to date. We present the results of a genome-wide linkage study of 95 families and linkage fine mapping of the 3q21-q29, 11q14-q25, 18p11-q23, and 19p13-q13 regions in an extended sample of 125 families of German descent. The locus with strongest evidence for linkage was mapped to 3q26 with a nonparametric linkage (NPL) score of 3.97 (empirical p value = 0.00055). This is the first step toward the identification of new susceptibility genes in AGA, a process which will provide important insights into the molecular and cellular basis of scalp hair loss.

Strong Compound-Risk Factors: Efficient Discovery Through Emerging Patterns and Contrast Sets

Odds ratio (OR), relative risk (RR) (risk ratio), and absolute risk reduction (ARR) (risk difference) are biostatistics measurements that are widely used for identifying significant risk factors in dichotomous groups of subjects. In the past, they have often been used to assess simple risk factors. In this paper, we introduce the concept of compound-risk factors to broaden the applicability of these statistical tests for assessing factor interplays. We observe that compound-risk factors with a high risk ratio or a big risk difference have an one-to-one correspondence to strong emerging patterns or strong contrast sets-two types of patterns that have been extensively studied in the data mining field. Such a relationship has been unknown to researchers in the past, and efficient algorithms for discovering strong compound-risk factors have been lacking. In this paper, we propose a theoretical framework and a new algorithm that unify the discovery of compound-risk factors that have a strong OR, risk ratio, or a risk difference. Our method guarantees that all patterns meeting a certain test threshold can be efficiently discovered. Our contribution thus represents the first of its kind in linking the risk ratios and ORs to pattern mining algorithms, making it possible to find compound-risk factors in large-scale data sets. In addition, we show that using compound-risk factors can improve classification accuracy in probabilistic learning algorithms on several disease data sets, because these compound-risk factors capture the interdependency between important data attributes.

Targeted skin overexpression of the mineralocorticoid receptor in mice causes epidermal atrophy, premature skin barrier formation, eye abnormalities, and alopecia

The mineralocorticoid receptor (MR) is a transcription factor of the nuclear receptor family, activation of which by aldosterone enhances salt reabsorption in the kidney. The MR is also expressed in nonclassical aldosterone target cells (brain, heart, and skin), in which its functions are incompletely understood. To explore the functional importance of MR in mammalian skin, we have generated a conditional doxycycline-inducible model of MR overexpression, resulting in double-transgenic (DT) mice [keratin 5-tTa/tetO-human MR (hMR)], targeting the human MR specifically to keratinocytes of the epidermis and hair follicle (HF). Expression of hMR throughout gestation resulted in early postnatal death that could be prevented by antagonizing MR signaling. DT mice exhibited premature epidermal barrier formation at embryonic day 16.5, reduced HF density and epidermal atrophy, increased keratinocyte apoptosis at embryonic day 18.5, and premature eye opening. When hMR expression was initiated after birth to overcome mortality, DT mice developed progressive alopecia and HF cysts, starting 4 months after hMR induction, preceded by dystrophy and cycling abnormalities of pelage HF. In contrast, interfollicular epidermis, vibrissae, and footpad sweat glands in DT mice were normal. This new mouse model reveals novel biological roles of MR signaling and offers an instructive tool for dissecting nonclassical functions of MR signaling in epidermal, hair follicle, and ocular physiology.

Androgenetic alopecia

Androgenetic alopecia (AGA), or male pattern hair loss, affects approximately 50% of the male population. AGA is an androgen-related condition in genetically predisposed individuals. There is no treatment to completely reverse AGA in advanced stages, but with medical treatment (eg, finasteride, minoxidil, or a combination of both), the progression can be arrested and partly reversed in the majority of patients who have mild to moderate AGA. Combination with hair restoration surgery leads to best results in suitable candidates. Physicians who specialize in male health issues should be familiar with this common condition and all the available approved treatment options.

Is baldness bad for the heart?

Various skin conditions are considered to be characteristic markers for elevated coronary disease risk. Over and above these established signs there are reports on other skin signs with possible associations with elevated coronary disease risk, i.e. the horizontal earlobe crease, high breast hair density, precocious graying and male pattern hair loss. A review of the literature is presented in this article, and the relevance of these symptoms is discussed as they are related to the possible myocardial disease risk. The available data on this topic are impressive, but on close assessment most of the studies are marred by methodical errors.

Health-related quality of life and physical well-being among a 63-year-old cohort of women with androgenetic alopecia; a Finnish population-based study

Background

The aim of this study was to assess the possible associations between female androgenetic alopecia (AGA), insulin resistance and health-related quality of life (HRQOL)-linked factors in women. We hypothesized that not only the mental aspects but also certain physical aspect of women's health, such as insulin resistance, have an important role in the determination of HRQOL among women with hair loss.

Methods

A population-based cohort of 330 healthy women aged 63 years, who participated in this study in the City of Oulu in Northern Finland, underwent a medical check-up including assessment of hair status on Ludwig's scale. Background data were collected with a standard questionnaire including a validated RAND 36-Item Health Survey (RAND-36) questionnaire.

Results

105 (31%) women with AGA and 225 (69%) controls completed the RAND-36 questionnaire. The women with AGA were more insulin-resistant than the women with normal hair (QUICKI 0.337 vs. 0.346, p = 0.012). Impaired glucose regulation (IGR) was more prevalent among the former than the latter group (39% vs. 25%). The mean RAND-36 scores were significantly lower on the dimensions of physical functioning, role limitation due to physical health and general health, but not on the mental or social dimensions, among the women with AGA compared with the controls. In multivariate logistic regression analyses with the lowest quintiles of the HRQOL dimensions as the dependent variables and AGA, depression, marital status, education and IGR or QUICKI as independent variables, AGA was independently associated with role limitations due to physical health (2.2, 95% CI 1.20–4.05, 2.45 95% CI 1.32–4.55, respectively).

Conclusion

In women aged 63 years, AGA was associated with role limitations due to physical health. Furthermore, the prevalence rates of IGR and insulin resistance measured by QUICKI were higher among the women with hair loss than those with normal hair.

Hair Loss Among Elderly Men: Etiology and Impact on Perceived Age

BACKGROUND

Androgenetic alopecia is the most common type of hair loss in men, but little is known about the etiology of androgenetic alopecia in elderly men and its impact on perceived age. Here we used a population-based twin study of men aged 70+ to assess the magnitude of the genetic component affecting hair loss and to examine the association between baldness and perceived age.

METHODS

In the fourth wave of The Longitudinal Study of Aging Danish Twins we obtained digital photos of the face and photos of the vertex area of 739 elderly male twins, including 148 intact twin pairs. The degree of baldness and perceived age were assessed in each twin by five and nine nurses, respectively. The heritability of balding was estimated using structural-equation analysis, and it was tested whether baldness was associated with estimations of age.

RESULTS

The intrapair correlation of degree of balding was consistently higher for monozygotic than for dizygotic twin pairs regardless of the baldness categorization used, and structural-equation analysis revealed a heritability of 79% (95% confidence interval, 0.40--0.85) for the mean baldness index. The remaining variation could be attributed to non-shared environmental effects. There was only a very weak and statistically nonsignificant association between baldness and overestimation of age.

CONCLUSIONS

The majority of the variation in baldness in elderly men can be explained by genetic factors, and hair quantity has little impact on perceived age in elderly men.

Genetic variation in the human androgen receptor gene is the major determinant of common early-onset androgenetic alopecia

Androgenetic alopecia (AGA), or male-pattern baldness, is the most common form of hair loss. Its pathogenesis is androgen dependent, and genetic predisposition is the major requirement for the phenotype. We demonstrate that genetic variability in the androgen receptor gene (AR) is the cardinal prerequisite for the development of early-onset AGA, with an etiological fraction of 0.46. The investigation of a large number of genetic variants covering the AR locus suggests that a polyglycine-encoding GGN repeat in exon 1 is a plausible candidate for conferring the functional effect. The X-chromosomal location of AR stresses the importance of the maternal line in the inheritance of AGA.

The natural history of androgenetic alopecia

Androgenetic alopecia (AGA) is the most common cause of hair loss, affecting up to 80% of men and 50% of women in their lifetime. Genetic predisposition to the disease is well known but the responsible genes have not been identified. Polymorphism in the androgen receptor gene has been recently detected in AGA.(1) Although the role of androgens, and particularly dihydrotestosterone (DHT), in causing the disease has been established for a long time, the natural history of AGA is still not completely understood. This paper reviews recent data about natural progression of the disease, as well as factors that may interfere with its course and long-term prognosis.

Antioxidant supplements for preventing gastrointestinal cancers

BACKGROUND

Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements in preventing gastrointestinal cancers.

SEARCH STRATEGY

We identified trials through the trials registers of the four Cochrane Review Groups on gastrointestinal diseases, The Cochrane Central Register of Controlled Trials on The Cochrane Library (Issue 1, 2003), MEDLINE, EMBASE, LILACS, and SCI-EXPANDED from inception to February 2003, and The Chinese Biomedical Database (March 2003). We scanned reference lists and contacted pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing antioxidant supplements to placebo/no intervention examining the incidence of gastrointestinal cancers.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials for inclusion and extracted data. The outcome measures were incidence of gastrointestinal cancers, overall mortality, and adverse events. Outcomes were reported as relative risks (RR) with 95% confidence interval (CI) based on fixed and random effects meta-analyses.

MAIN RESULTS

We identified 14 randomised trials (170,525 participants), assessing beta-carotene (9 trials), vitamin A (4 trials), vitamin C (4 trials), vitamin E (5 trials), and selenium (6 trials). Trial quality was generally high. Heterogeneity was low to moderate. Neither the fixed effect (RR 0.96, 95% CI 0.88 to 1.04) nor random effects meta-analyses (RR 0.90, 95% CI 0.77 to 1.05) showed significant effects of supplementation with antioxidants on the incidences of gastrointestinal cancers. Among the seven high-quality trials reporting on mortality (131,727 participants), the fixed effect (RR 1.06, 95% CI 1.02 to 1.10) unlike the random effects meta-analysis (RR 1.06, 95% CI 0.98 to 1.15) showed that antioxidant supplements significantly increased mortality. Two low-quality trials (32,302 participants) found no significant effect of antioxidant supplementation on mortality. The difference between the mortality estimates in high- and low-quality trials was significant by test of interaction (z = 2.10, P = 0.04). Beta-carotene and vitamin A (RR 1.29, 95% CI 1.14 to 1.45) and beta-carotene and vitamin E (RR 1.10, 95% CI 1.01 to 1.20) significantly increased mortality, while beta-carotene alone only tended to do so (RR 1.05, 95% CI 0.99 to 1.11). Increased yellowing of the skin and belching were non-serious adverse effects of beta-carotene. In four trials (three with unclear/inadequate methodology), selenium showed significant beneficial effect on gastrointestinal cancer incidences.

REVIEWERS' CONCLUSIONS

We could not find evidence that antioxidant supplements prevent gastrointestinal cancers. On the contrary, they seem to increase overall mortality. The potential cancer preventive effect of selenium should be studied in adequately conducted randomised trials.

Influence of site classification on cancer incidence rates: an analysis of gastric cardia carcinomas

BACKGROUND

Recent reports suggest that the incidences of cardia and gastroesophageal junction carcinomas have increased markedly. The influence of improvements in cancer site classification (i.e., from no specific site to a specific site) on these incidence rates is unknown.

METHODS

We analyzed data for all gastric cancers reported to the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) cancer registries from 1974 through 1998. We compared incidence figures adjusted for improvements in site classification with the standard unadjusted incidence rates traditionally reported from SEER data. All analyses used two-sided statistical tests.

RESULTS

Among white males, the proportion of gastric cancers with an unspecified location decreased from 38% from 1974 to 1976 to 14% in 1996 to 1998. Between 1974-1976 and 1996-1998, the adjusted cardia cancer incidence rate for white males was unchanged (5.3% increase, from 3.6 to 3.8 per 100,000 population/year, respectively; P =.59), whereas the unadjusted cardia cancer incidence rate underwent a statistically significant increase (77% increase, from 1.9 to 3.4 per 100 000 population/year, respectively; P<.001). During the same period, the adjusted noncardia gastric cancer incidence rate in white males decreased from 6.8 to 3.8 per 100,000 population/year (P<.001), an absolute decrease more than twice as large as that seen using standard unadjusted SEER data (from 4.5 to 3.2 per 100,000 population/year; P<.001). Similar findings were observed for black males.

CONCLUSIONS

Improved specification of gastric cancer sites may largely account for the purported increase in cardia cancer incidence in recent decades. Noncardia gastric cancer incidence may be decreasing much more rapidly than previously appreciated. These results illustrate the potentially large influence of changes in site classification on some cancer incidence rates.

Is androgenic alopecia a result of endocrine effects on the vasculature?

Androgenic alopecia is a condition of concern for many patients. Though much has been learned about this condition, the exact pathophysiological mechanism is yet to be established. Currently most study concerning androgenic alopecia has focused on the effects of androgens on the pilosebaceous unit itself. An area of study that has received considerably less attention is that of androgens inducing baldness by indirect effects, that is, effects on tissues other than the pilosebaceous unit. In this paper, the author offers a novel hypothesis in which androgenic hair loss is mediated via the effects of androgens on the vasculature supplying the scalp. In this new hypothesis androgens effect anatomical changes in the vasculature of susceptible individuals, resulting in an environment in which hair growth is hindered and eventually ceases. The author discusses past studies demonstrating the effects of androgens on vessels and how these effects may relate to anatomical changes in the vasculature leading to hair loss. Also included is a discussion on future experimentation to test this new hypothesis.

Hyperinsulinemic diseases of civilization: more than just Syndrome X

Compensatory hyperinsulinemia stemming from peripheral insulin resistance is a well-recognized metabolic disturbance that is at the root cause of diseases and maladies of Syndrome X (hypertension, type 2 diabetes, dyslipidemia, coronary artery disease, obesity, abnormal glucose tolerance). Abnormalities of fibrinolysis and hyperuricemia also appear to be members of the cluster of illnesses comprising Syndrome X. Insulin is a well-established growth-promoting hormone, and recent evidence indicates that hyperinsulinemia causes a shift in a number of endocrine pathways that may favor unregulated tissue growth leading to additional illnesses. Specifically, hyperinsulinemia elevates serum concentrations of free insulin-like growth factor-1 (IGF-1) and androgens, while simultaneously reducing insulin-like growth factor-binding protein 3 (IGFBP-3) and sex hormone-binding globulin (SHBG). Since IGFBP-3 is a ligand for the nuclear retinoid X receptor alpha, insulin-mediated reductions in IGFBP-3 may also influence transcription of anti-proliferative genes normally activated by the body's endogenous retinoids. These endocrine shifts alter cellular proliferation and growth in a variety of tissues, the clinical course of which may promote acne, early menarche, certain epithelial cell carcinomas, increased stature, myopia, cutaneous papillomas (skin tags), acanthosis nigricans, polycystic ovary syndrome (PCOS) and male vertex balding. Consequently, these illnesses and conditions may, in part, have hyperinsulinemia at their root cause and therefore should be classified among the diseases of Syndrome X.

Occult fungal infection is the underlying pathogenic cause of atherogenesis

Atherosclerosis is the underlying cause of coronary heart disease (CHD). Atherogenesis is supposed to result from response to injury and is considered an inflammatory condition. A variety of infectious agents have been investigated as the underlying risk factor for atherogenesis, however, none have been proved to be causally linked. Also several interventions against these agents have not been proved to be of benefit in trials. The role of fungal infection, however, has not been explored in sufficient detail. Baldness particularly male pattern baldness and coronary artery disease have been linked in several epidemiological studies. There is some evidence that this type of baldness could be due to fungal infection and this link is being established even though traditionally male pattern baldness was associated with androgen effect. Seborrheic dermatitis and Pityrosporum infection have been causally linked and the benefit derived from antifungal shampoo in male pattern baldness, gives further credence to the link with fungal infection. Here it is being hypothesized that fungal infection is the underlying risk factor for both baldness and CHD. Several interventions, which have proved beneficial in CHD like statins and drug coated stents, also have anti-fungal effects, lending further credence to the present hypothesis.

Population attributable risks of esophageal and gastric cancers

BACKGROUND

Several risk factors have been identified for esophageal adenocarcinoma, gastric cardia adenocarcinoma, esophageal squamous cell carcinoma, and noncardia gastric adenocarcinoma, but no study has comprehensively examined their contributions to the cancer burden in the general population. Herein, we estimate the population attributable risks (PARs) for various risk factors observed in a multicenter population-based case-control study.

METHODS

We calculated PARs by using 293 patients with esophageal adenocarcinoma, 261 with gastric cardia adenocarcinoma, 221 with esophageal squamous cell carcinoma, 368 with noncardia gastric adenocarcinoma, and 695 control subjects. We included smoking for all four tumor types and Helicobacter pylori infection for noncardia gastric adenocarcinoma as established causal risk factors as well as several other factors for which causality is under evaluation.

RESULTS

Ever smoking, body mass index above the lowest quartile, history of gastroesophageal reflux, and low fruit and vegetable consumption accounted for 39.7% (95% confidence interval [CI] = 25.6% to 55.8%), 41.1% (95% CI = 23.8% to 60.9%), 29.7% (95% CI = 19.5% to 42.3%), and 15.3% (95% CI = 5.8% to 34.6%) of esophageal adenocarcinomas, respectively, with a combined PAR of 78.7% (95% CI = 66.5% to 87.3%). Ever smoking and body mass index above the lowest quartile were responsible for 45.2% (95% CI = 31.3% to 59.9%) and 19.2% (95% CI = 4.9% to 52.0%) of gastric cardia adenocarcinomas, respectively, with a combined PAR of 56.2% (95% CI = 38.1% to 72.8%). Ever smoking, alcohol consumption, and low fruit and vegetable consumption accounted for 56.9% (95% CI = 36.6% to 75.1%), 72.4% (95% CI = 53.3% to 85.8%), and 28.7% (95% CI = 11.1% to 56.5%) of esophageal squamous cell carcinomas, respectively, with a combined PAR of 89.4% (95% CI = 79.1% to 95.0%). Ever smoking, history of gastric ulcers, nitrite intake above the lowest quartile, and H. pylori infection were responsible for 18.3% (95% CI = 6.5% to 41.8%), 9.7% (95% CI = 5.4% to 16.8%), 40.7% (95% CI = 23.4% to 60.7%), and 10.4% (95% CI = 0.3% to 79.6%) of noncardia gastric adenocarcinomas, respectively, with a combined PAR of 59.0% (95% CI = 16.2% to 91.4%).

CONCLUSION

In this population, a few known risk factors account for a majority of esophageal and gastric cancers. These results suggest that the incidence of these cancers may be decreased by reducing the prevalence of smoking, gastroesophageal reflux, and being overweight and by increasing the consumption of fruits and vegetables.

Hormone-induced aberrations in electromagnetic adhesion signaling as a developmental factor of androgenetic alopecia

In androgenetic alopecia, overactivation of the androgen hormone cascade in genetically predisposed persons leads to miniaturization of the dermal papilla of the hair follicle and to reduction in the number of papilla cells in the scalp, but the mechanisms explaining this miniaturization have remained unclear. According to our hypothesis, the increase of dihydrotestosterone (DHT) production in the overactive androgen state inhibits cell mitosis in the dermal papilla and contributes to the induction of programmed cell death (apoptosis). Normally, DNA molecules have a negative charge, which doubles in every cell mitosis. In the catagen and telogen phases, the sulphur-rich hair moves upwards, dehydrates and develops an increasing positive charge. In a normal hair-growth cycle, the epithelial column shortens and the secondary germ is formed and it invaginates the dermal papilla by electromagnetic attraction. In the mitotic inhibition state induced by DHT, the negative charge decreases, leading to a weakening of the electromagnetic adhesion forces and weaker electrical attraction between the undifferentiated germ cells and the dermal papilla. Insulin resistance has an additional pathogenic role in the excessive miniaturization of the hair follicle. The vasoactive substances associated with endothelial dysfunction in insulin resistance induce microcirculatory disturbance, perifollicular vasoconstriction and stimulation of smooth muscle cell proliferation in the vascular wall. This leads to microvascular insufficiency and local tissue hypoxia and progressive miniaturization of hair follicles.

Polymorphism of the androgen receptor gene is associated with male pattern baldness

The common heritable loss of scalp hair known as male pattern baldness or androgenetic alopecia affects up to 80% of males by age 80. A balding scalp is characterized by high levels of the potent androgen dihydrotestosterone and increased expression of the androgen receptor gene. To determine if the androgen receptor gene is associated with male pattern baldness, we compared allele frequencies of the androgen receptor gene polymorphisms (StuI restriction fragment length polymorphism and two triplet repeat polymorphisms) in cases with cosmetically significant baldness (54 young and 392 older men) and controls (107 older men) with no indication of baldness. The androgen receptor gene StuI restriction site was found in all but one (98.1%) of the 54 young bald men (p = 0.0005) and in 92.3% of older balding men (p = 0.000004) but in only 76.6% of nonbald men. The combination of shorter CAG and GGC triplet repeat lengths was also more prevalent in bald men (p = 0.03). The ubiquity of the androgen receptor gene StuI restriction site, and higher incidence of shorter triplet repeat haplotypes in bald men suggests that these markers are very close to a functional variant that is a necessary component of the polygenic determination of male pattern baldness. Functional mutation in or near the androgen receptor gene may explain the reported high levels of expression of this gene in the balding scalp.