Male-pattern baldness

About: Male-pattern baldness is a research topic. Over the lifetime, 760 publications have been published within this topic receiving 19120 citations.

Patterned loss of hair in man; types and incidence.

Abstract: This account summarizes certain aspects of a study which is to be published in detail eisewhere and has the following aims: (1) To establish types or categories of scalp hairiness which can be used as standards for classitication and grading of the extent of common ba1dness.t (2) To survey the incidence of these scalp types in members of each sex throughout life, beginning with the first appearance of hair in the fetus. (3) To gain information regarding the relationship of scdp types to factors which influence the development of baldness, in particular to genetic, age, and endocrine factors. (4) To ascertain if bald men, as compared with men who did not become bald, have higher titers of urinary ketosteroids or a greater development of a secondary sex character, axillary hair, which can be measured quantitatively and used as an index of certain aspects of the endocrine status. This part af the study stems from the fact that common baldness is induced by androgenic stimulation (Hamilton, 1942). ( 5 ) To test if the tendency to acquire baldness of the scalp is associated with a disposition to baldness on another part of the body where alopecia is common, i e . , on the lateral surfaces of the legs.

Male pattern baldness: classification and incidence.

Abstract: The need for a widely accepted, accurate, and reproducible standard of classification for male pattern baldness has increased with the advent and increasing popularity of hair transplant surgery. This report establishes such a classification, and reports its use in determining the incidence of male pattern baldness at various ages in 1,000 white adult male subjects. The action of testosterone as an incitant in male pattern baldness is well known, but this study points out the continued effect of time, even in later years. Since most hair transplant surgery is peformed on subjects with male pattern baldness, and because the success of hair transplant surgery is largely dependent on proper patient selection, a complete understanding of male pattern baldness is essential for consistently good results with hair transplantation.

Tissue distribution and ontogeny of steroid 5 alpha-reductase isozyme expression.

Abstract: The synthesis of dihydrotestosterone is catalyzed by steroid 5 alpha-reductase isozymes, designated types 1 and 2. Mutation of type 2 results in male pseudohermaphroditism, in which the external genitalia are phenotypically female at birth. Two striking and unexplained features of this disorder are that external genitalia of affected males undergo virilization during puberty and that these individuals have less temporal hair regression. The tissue-specific and developmental expression patterns of the 5 alpha-reductase isozymes were investigated by immunoblotting. The type 1 isozyme is not detectable in the fetus, is transiently expressed in newborn skin and scalp, and permanently expressed in skin from the time of puberty. There was no qualitative difference in 5 alpha-reductase type 1 expression between adult balding vs. nonbalding scalp. The type 2 isozyme is transiently expressed in skin and scalp of newborns. Type 2 is the predominant isozyme detectable in fetal genital skin, male accessory sex glands, and in the prostate, including benign prostatic hyperplasia and prostate adenocarcinoma tissues. Both isozymes are expressed in the liver, but only after birth. These results are consistent with 5 alpha-reductase type 1 being responsible for virilization in type 2-deficient subjects during puberty, and suggest that the type 2 isozyme may be an initiating factor in development of male pattern baldness.

Polycystic ovaries and premature male pattern baldness are associated with one allele of the steroid metabolism gene CYP17

Abstract: Fourteen Caucasian families with 81 affected individuals have been assessed in which polycystic ovaries/male pattern baldness (PCO/MPB) segregates as an autosomal dominant phenotype (1). The gene CYP17, coding for P450c17 alpha (17 alpha-hydroxylase; 17/20 lyase) on chromosome 10q24.3 is the rate-limiting step in androgen biosynthesis. We have identified a new single base change in the 5' promoter region of CYP17 by heteroduplex analysis. This creates an additional SP1-type (CCACC box) promoter site, which may cause increased expression. This base change also creates a recognition site for the restriction enzyme MspA1 allowing a simple screening procedure. There is a significant association between the presence of this base change (A2) and the affected state for consecutively identified Caucasian women with PCO as compared either to consecutively matched controls (P = 0.03) with an odds ratio for those with at least one A2 allele of 3.57, or to a random population (P = 0.02) with an odds ratio of 2.50. Within the fourteen families, members with PCO or MPB have a significant association with the occurrence of at least one A2 allele compared to their normal relatives, with an odds ratio of 2.20 (P = 0.05). The base change does not cosegregate with the affected phenotype within the families showing association, demonstrating that this mutation of CYP17 does not cause PCO/MPB. Variation in the A2 allele of the CYP17 gene is a significant factor modifying the expression of PCO/MPB in families where it has been demonstrated to segregate as a single gene disorder, but it is excluded as the primary genetic defect.