Baldness and coronary heart disease risk factors

Cholesterol homeostasis in hair follicle keratinocytes is disrupted by impaired ABCA5 activity

The importance of cholesterol in hair follicle biology is underscored by its links to the pathogenesis of alopecias and hair growth disorders. Reports have associated defects in ABCA5, a membrane transporter, with altered keratinocyte cholesterol distribution in individuals with a form of congenital hypertrichosis, yet the biological basis for this defect in hair growth remains unknown. This study aimed to determine the impact of altered ABCA5 activity on hair follicle keratinocyte behaviour. Primary keratinocytes isolated from the outer root sheath of plucked human hair follicles were utilised as a relevant cell model. Following exogenous cholesterol loading, an increase in ABCA5 co-localisation to intracellular organelles was seen. Knockdown of ABCA5 revealed a dysregulation in cholesterol homeostasis, with LXR agonism leading to partial restoration of the homeostatic response. Filipin staining and live BODIPY cholesterol immunofluorescence microscopy revealed a reduction in endo-lysosomal cholesterol following ABCA5 knockdown. Analysis of oxysterols showed a significant increase in the fold change of 25-hydroxycholesterol and 7-β-hydroxycholesterol following cholesterol loading in ORS keratinocytes, after ABCA5 knockdown. These data suggest a role for ABCA5 in the intracellular compartmentalisation of free cholesterol in primary hair follicle keratinocytes. The loss of normal homeostatic response, following the delivery of excess cholesterol after ABCA5 knockdown, suggests an impact on LXR-mediated transcriptional activity. The loss of ABCA5 in the hair follicle could lead to impaired endo-lysosomal cholesterol transport, impacting pathways known to influence hair growth. This avenue warrants further investigation.

Cholesterol homeostasis: Links to hair follicle biology and hair disorders

Lipids and lipid metabolism are critical factors in hair follicle (HF) biology, and cholesterol has long been suspected of influencing hair growth. Altered cholesterol homeostasis is involved in the pathogenesis of primary cicatricial alopecia, mutations in a cholesterol transporter are associated with congenital hypertrichosis, and dyslipidaemia has been linked to androgenic alopecia. The underlying molecular mechanisms by which cholesterol influences pathways involved in proliferation and differentiation within HF cell populations remain largely unknown. As such, expanding our knowledge of the role for cholesterol in regulating these processes is likely to provide new leads in the development of treatments for disorders of hair growth and cycling. This review describes the current state of knowledge with respect to cholesterol homeostasis in the HF along with known and putative links to hair pathologies.

The degree of hair graying as an independent risk marker for coronary artery disease, a CT coronary angiography study

BACKGROUND

Cardiovascular disease is a leading cause of death worldwide. Aging is an unavoidable coronary risk factor and is associated with dermatological signs that could be a marker for increased coronary risk. We tested the hypothesis that hair graying as a visible marker of aging is associated with risk of coronary artery disease (CAD) independent of chronological age.

METHODS

This cross-sectional study included 545 males who underwent a computed tomography coronary angiography (CTCA) for suspicious of CAD, patients were divided into subgroups according to the percentage of gray/white hairs (Hair Whitening Score, HWS: 1-5) and to the absence or presence of CAD.

RESULTS

CAD was prevalent in 80% of our studied population, 255 (46.8%) had 3 vessels disease with mean age of 53.2 ± 10.7 yrs. Hypertension, diabetes and dyslipidemia were more prevalent in CAD group (P = 0.001, P = 0.001, and P = 0.003, respectively). Patients with CAD had statistically significant higher HWS (32.1% vs 60.1%, p < 0.001) and significant coronary artery calcification (<0.001). Multivariate regression analysis showed that age (odds ratio (OR): 2.40, 95% confidence interval (CI): [1.31-4.39], p = 0.004), HWS (OR: 1.31, 95% CI: [1.09-1.57], p = 0.004), hypertension (OR: 1.63, 95% CI: [1.03-2.58], p = 0.036), and dyslipidemia (OR: 1.61, 95% CI: [1.02-2.54], p = 0.038) were independent predictors of the presence of atherosclerotic CAD, and only age (p < 0.001) was significantly associated with HWS.

CONCLUSIONS

Higher HWS was associated with increased coronary artery calcification and risk of CAD independent of chronological age and other established cardiovascular risk factors.

Gender-specific risk factors for androgenetic alopecia in the Korean general population: Associations with medical comorbidities and general health behaviors

BACKGROUND

The relationships between androgenetic alopecia (AGA) and various factors related to metabolic syndrome have been demonstrated in previous studies. However, it remains unclear because of inconsistent results. We investigated the associations between AGA and various risk factors related to metabolic syndrome according to gender.

METHODS

We conducted a population-based cross-sectional survey of 2028 Koreans (1050 men, 978 women). The basic and specific (BASP) classification was used for diagnosis of AGA. We collected information on risk factors though questionnaires and medical records.

RESULTS

AGA was significantly associated with age, family history of AGA, hypertension, diabetes mellitus, and waist circumference in both genders. Female subjects with AGA were more likely to have cerebrovascular disease, dyslipidemia, and obesity; however, these associations were not observed in the male subjects. When multiple regression analysis was applied, there was a significant relationship between hypertension and AGA in male subjects. However, there was no statistically significant association in female subjects.

CONCLUSION

The different results according to gender might arise from different mechanisms of AGA. There was a significant relationship between hypertension and AGA in male subjects. Evaluation of blood pressure in male patients with AGA might facilitate interventions for hypertension.

A hypothetical pathogenesis model for androgenic alopecia: clarifying the dihydrotestosterone paradox and rate-limiting recovery factors

Androgenic alopecia, also known as pattern hair loss, is a chronic progressive condition that affects 80% of men and 50% of women throughout a lifetime. But despite its prevalence and extensive study, a coherent pathology model describing androgenic alopecia's precursors, biological step-processes, and physiological responses does not yet exist. While consensus is that androgenic alopecia is genetic and androgen-mediated by dihydrotestosterone, questions remain regarding dihydrotestosterone's exact role in androgenic alopecia onset. What causes dihydrotestosterone to increase in androgenic alopecia-prone tissues? By which mechanisms does dihydrotestosterone miniaturize androgenic alopecia-prone hair follicles? Why is dihydrotestosterone also associated with hair growth in secondary body and facial hair? Why does castration (which decreases androgen production by 95%) stop pattern hair loss, but not fully reverse it? Is there a relationship between dihydrotestosterone and tissue remodeling observed alongside androgenic alopecia onset? We review evidence supporting and challenging dihydrotestosterone's causal relationship with androgenic alopecia, then propose an evidence-based pathogenesis model that attempts to answer the above questions, account for additionally-suspected androgenic alopecia mediators, identify rate-limiting recovery factors, and elucidate better treatment targets. The hypothesis argues that: (1) chronic scalp tension transmitted from the galea aponeurotica induces an inflammatory response in androgenic alopecia-prone tissues; (2) dihydrotestosterone increases in androgenic alopecia-prone tissues as part of this inflammatory response; and (3) dihydrotestosterone does not directly miniaturize hair follicles. Rather, dihydrotestosterone is a co-mediator of tissue dermal sheath thickening, perifollicular fibrosis, and calcification - three chronic, progressive conditions concomitant with androgenic alopecia progression. These conditions remodel androgenic alopecia-prone tissues - restricting follicle growth space, oxygen, and nutrient supply - leading to the slow, persistent hair follicle miniaturization characterized in androgenic alopecia. If true, this hypothetical model explains the mechanisms by which dihydrotestosterone miniaturizes androgenic alopecia-prone hair follicles, describes a rationale for androgenic alopecia progression and patterning, makes sense of dihydrotestosterone's paradoxical role in hair loss and hair growth, and identifies targets to further improve androgenic alopecia recovery rates: fibrosis, calcification, and chronic scalp tension.

Safety of Topical Minoxidil Solution: A One-Year, Prospective, Observational Study

Background:

Topical minoxidil solution (TMS) is widely used for androgenetic alopecia (AGA), and this is the first report of a large safety trial.

Objectives:

The aim of the study was to evaluate the safety profile of TMS by comparing hospitalization and death rates among subjects using TMS with controls. Cardiovascular safety and pregnancy outcomes were evaluated, and usage patterns were described.

Methods:

All subjects were followed at baseline, 3, 6, 9, and 12 months. Usage patterns, pregnancy status, overnight hospital stays, and cardiovascular risk factors were evaluated. Subjects rated effectiveness of TMS in the treatment of AGA. Statistical analyses were conducted to determine if TMS was associated with an increased risk of death or hospitalization.

Results:

TMS is a safe and effective treatment for AGA. There were no increases in cardiovascular events and no apparent increased risk for adverse pregnancy outcomes.

Conclusions:

This large, prospective study demonstrated the overall safety of TMS in the treatment of AGA.

Visible aging signs as risk markers for ischemic heart disease: Epidemiology, pathogenesis and clinical implications

Association of common aging signs (i.e., male pattern baldness, hair graying, and facial wrinkles) as well as other age-related appearance factors (i.e., arcus corneae, xanthelasmata, and earlobe crease) with increased risk of ischemic heart disease was initially described in anecdotal reports from clinicians observing trends in the physical appearance of patients with ischemic heart disease. Following these early observations numerous epidemiological studies have reported these associations. Since the prevalences of both visible aging signs and ischemic heart disease have a strong correlation with increasing age, it has been extensively debated whether the observed associations could be entirely explained by a common association with age. Furthermore, the etiologies of the visible aging signs are rarely fully understood, and pathophysiological explanations for these associations remain controversial, and are mostly speculative. As a consequence of inconsistent findings and lack of mechanistic explanations for the observed associations with ischemic heart disease, consensus on the clinical importance of these visible aging signs has been lacking. The aim of this review is for each of the visible aging signs to (i) review the etiology, (ii) to discuss the current epidemiological evidence for an association with risk of ischemic heart disease, and (iii) to present possible pathophysiological explanations for these associations. Finally this review discusses the potential clinical implications of these findings.

Androgenetic alopecia as an indicator of metabolic syndrome and cardiovascular risk

Numerous studies have investigated a probable association between androgenetic alopecia (AGA) and cardiovascular disease (CVD) by researching limited and dispersed parameters. We aimed to evaluate both traditional and non-traditional cardiovascular risk factors in male patients with early-onset AGA. This case-control study included 68 participants: 51 male patients with early-onset AGA and 17 healthy male controls. Patients with AGA were classified into three groups according to the Hamilton-Norwood scale and the presence of vertex hair loss. Traditional and non-traditional cardiovascular risk factors were examined in all study subjects. Metabolic syndrome was diagnosed in 25 patients with AGA and in two control subjects (p < 0.05). The carotid intima-media thickness values were found to be significantly higher in patients with vertex pattern AGA than in patients without vertex baldness and controls (p < 0.05). The pulse-wave velocity values were also found to be significantly higher in patients (p < 0.001). A limitation of this study was the small study population. In conclusion, vertex pattern AGA appears to be a marker for early atherosclerosis. This finding supports the hypothesis that early-onset AGA alone could be an independent risk factor for CVD and metabolic syndrome.

Premature Graying of Hair: An Independent Risk Marker for Coronary Artery Disease in Smokers - A Retrospective Case Control Study

BACKGROUND

Premature graying of hair as a risk marker among young smokers has a potential of identifying coronary artery disease (CAD) at a very early stage. There is absence of literature that assesses premature graying of hair as an independent marker of CAD in smokers.

MATERIAL AND METHODS

The present single-centre case control study enrolled a total of 62 consecutive chronic smokers (≤ 45 years) (Group I) and 60 consecutive young CAD patients (≤45 years) who were chronic smokers (Group II). Another group comprising of 114 patients (≤45 years) having no smoking history and no cardiac ailments either (Group III) was enrolled as control population. All subjects were males. A detailed history and clinical examination regarding conventional coronary risk factors and carotid intima media thickness was done in both groups.

RESULTS

The carotid intima media thickness, dyslipidemia and blood pressure were significantly higher in group I and II as compared to group III. When the groups were compared for graying of hair, it was found that the group II (i.e., smokers and CAD) had maximum prevalence of graying which was significantly higher than the control as well as smoker groups. The presence of premature graying of hair was associated with 3.24 times the risk of CAD on multiple logistic regression analysis.

CONCLUSION

The presence of premature graying of hair was associated with an increased risk of CAD in young smokers. Premature graying of hair can be used as preliminary evidence by clinicians for classifying patients at risk for premature CAD especially in smokers.

Alopecia and its association with coronary heart disease and cardiovascular risk factors: a meta-analysis

BACKGROUND

Alopecia has been associated with an increased risk of coronary heart disease as well as the following risk factors for cardiovascular disease: hyperinsulinaemia, insulin resistance, metabolic syndrome, dyslipidaemia, and hypertension. We performed a meta-analysis to quantitatively determine the level of risk of coronary heart disease and risk factors in individuals with alopecia.

METHODS

A systematic literature search was conducted using several databases. We calculated pooled odds ratios and 95% confidence intervals using a random effects model.

RESULTS

In total, 31 studies comprising 29,254 participants with alopecia were eligible for the meta-analysis and showed that alopecia is associated with an increased risk of coronary heart disease (OR 1.22, 95% CI: 1.07-1.39), hyperinsulinaemia (OR 1.97, 95% CI: 1.20-3.21), insulin resistance (OR 4.88, 95% CI: 2.05-11.64), and metabolic syndrome (OR 4.49, 95% CI: 2.36-8.53). Individuals with alopecia were also shown to be more likely compared to those without alopecia to have higher serum cholesterol levels (OR 1.60, 95% CI: 1.17-2.21), higher serum triglyceride levels (OR 2.07, 95% CI: 1.32-3.25), higher systolic blood pressures (OR 1.73, 95% CI: 1.29-2.33), and higher diastolic blood pressures (OR 1.59, 95% CI: 1.16-2.18).

CONCLUSIONS

Alopecia is associated with an increased risk of coronary heart disease, and there appears to be a dose-response relationship with degree of baldness whereby the greater the severity of alopecia, the greater the risk of coronary heart disease. Alopecia is also associated with an increased risk of hypertension, hyperinsulinaemia, insulin resistance, metabolic syndrome, and having elevated serum total cholesterol and triglyceride levels.

Androgenetic alopecia and risk of coronary artery disease

Background:

Androgenetic alopecia (AGA) or male pattern baldness (MPB) has been found to be associated with the risk of coronary artery disease (CAD). The well-known risk factors are family history of CAD, hypertension, increased body mass index (BMI), central obesity, hyperglycemia, and dyslipidemia. The newer risk factors are serum lipoprotein-a (SL-a), serum homocysteine (SH), and serum adiponectin (SA).

Aim:

Identifying individuals at risk of CAD at an early age might help in preventing CAD and save life. Hence, a comparative study of CAD risk factors was planned in 100 males of AGA between the age of 25 and 40 years with equal number of age- and sex-matched controls.

Materials and Methods:

Patients of AGA grade II or more of Hamilton and Norwood (HN) Scale and controls were examined clinically and advised blood test. The reports were available for fasting blood sugar (FBS), serum total serum cholesterol (SC) in 64 cases, 64 controls; lipoproteins (high, low, very low density, HDL, LDL, VLDL), serum triglycerides (ST) in 63 cases, 63 controls; SL-a in 63 cases, 74 controls; SH in 56 cases, 74 controls; and SA in 62 cases, 74 controls.

Results:

In these cases family history (FH) of AGA and CAD was significantly high. The blood pressure (BP) was also found to be significantly high in the cases. The difference of mean serum HDL, LDL, VLDL, ST, SH, and SL-a in cases and controls were statistically significant and with increasing grade of AGA, the risk factors also increased.

Conclusion:

Patients with AGA appear to be at an increased risk of developing CAD, therefore, clinical evaluation of cases with AGA of grade II and above may be of help in preventing CAD in future.

Alopecia due to common metabolic diseases

Alopecia is an important condition presenting with excessive hair loss. The problem of alopecia is important concern in trichology. Sometimes, alopecia can be due to complicated etiologies. The good examples are metabolic diseases. In this article, the authors will present the details of alopecia due to some important metabolic diseases. Special focus is made on diagnosis and treatment.

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 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.

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.

Associaton of Insulin Resistance Linked Diseases and Hair Loss in Elderly Men. Finnish Population-based Study

Previous investigations have shown an association of androgenetic alopecia (AGA) with insulin resistance related disorders such as ischemic heart disease. An association between AGA and anthropometric abnormalities linked with insulin resistance and heredity in women aged 63 years has also been shown. We therefore compared 63-year-old men with AGA and ones with normal hair status for insulin resistance linked parameters. A population of 245 men aged 63 years, who were participants in a population-based cross-sectional study in the City of Oulu, underwent a medical check-up including assessment of hair status on the Hamilton-Norwood scale and determination of anthropometric measures, blood pressure, fasting glucose and serum lipids. Fifty eight per cent of the men reported extensive hair loss (grade III-VII). Hypertension and the use of antihypertensive drugs were common among men with AGA (61% vs. 45% and 50% vs. 26%, respectively). The rates of diabetes and hyperinsulinemia (21% vs. 12% and 61% vs. 49%) were higher among men with AGA compared to those with normal hair status but no difference was seen in other factors. Our findings show that AGA is common among Finnish men aged 63 years but that it is also associated with insulin linked disturbances, such as hypertension and diabetes. Such men developing AGA might benefit from attention in medical check-up.

Family History and Risk of Hair Loss

INTRODUCTION

The genetic basis of androgenetic alopecia (AGA) is well accepted in the medical community and among the general population. However, rigorous studies investigating the familial basis of AGA are lacking. The purpose of the current study was to explore the relationship between family history and expression of AGA in a sample of men from the general community.

METHODS

Hair loss was assessed by an independent observer trained by an expert dermatologist using the Norwood/Hamilton classification scale and a 7-point global description of hair loss. Men were classified into two groups, one as having little or no hair loss and the other having hair loss. The family history of hair loss in parents and grandparents was assessed by subject self-report.

RESULTS

Adjusting for age, men whose fathers had hair loss were 2.5 times as likely to have had some level of hair loss compared to men whose fathers had no hair loss (95% CI: 1.3-4.9). Likewise, men whose fathers had hair loss were twice as likely to have hair loss than men whose fathers had no hair loss even after adjusting for age (OR = 2.1, 95% CI: 1.2-3.7 and OR = 2.5, 95% CI: 1.4-4.7 for Norwood/Hamilton and global description of hair loss assessments, respectively).

CONCLUSION

Results suggest that the probability of male pattern hair loss is dependent on family history and age. Hair loss in a man's father also appears to play an important role in increasing a man's risk of hair loss, either in conjunction with a history of hair loss in the mother or hair loss in the maternal grandfather.

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.

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.