michael barry
Senior Member
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- 14
This was posted on another site...........
The first one is another recent genetic study which shows that a polymorphism in the ectodysplasin-A receptor gene is what gives Asians thick hair. The second study shows that ectodysplasin helps control the switch from anagen to catagen (early termination of anagen -- short growth cycles -- are a feature of male pattern baldness). Gene therapy for baldness would be really, really nice if it happens someday.
Hum Mol Genet. 2008 Mar 15;17(6):835-43.
A scan for genetic determinants of human hair morphology: EDAR is associated with Asian hair thickness.
Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Hongo, Tokyo, Japan.
Hair morphology is one of the most differentiated traits among human populations. However, genetic backgrounds of hair morphological differences among populations have not been clarified yet. In addition, little is known about the evolutionary forces that have acted on hair morphology. To identify hair morphology-determining genes, the levels of local genetic differentiation in 170 genes that are related to hair morphogenesis were evaluated by using data from the International HapMap project. Among highly differentiated genes, ectodysplasin A receptor (EDAR) harboring an Asian-specific non-synonymous single nucleotide polymorphism (1540T/C, 370Val/Ala) was identified as a strong candidate. Association studies between genotypes and hair morphology revealed that the Asian-specific 1540C allele is associated with increase in hair thickness. Reporter gene assays suggested that 1540T/C affects the activity of the downstream transcription factor NF-kappaB. It was inferred from geographic distribution of 1540T/C and the long-range haplotype test that 1540C arose after the divergence of Asians from Europeans and its frequency has rapidly increased in East Asian populations. These findings lead us to conclude that EDAR is a major genetic determinant of Asian hair thickness and the 1540C allele spread through Asian populations due to recent positive selection.
PMID: 18065779 [PubMed - in process]
Involvement of the Edar signaling in the control of hair follicle involution (catagen).
Department of Dermatology, Boston University School of Medicine, 609 Albany St., Boston, MA 02118, USA.
Ectodysplasin (Eda) and its receptor (Edar) are required for normal development of several ectodermal derivatives including hair follicles (HFs). Here, we show that during the murine hair cycle the expression of Eda A1, Edar, Edaradd, and TRAF6 transcripts are minimal in the resting phase and maximal during HF transition from active growth to regression (catagen). Eda A1 mRNA and Edar proteins were expressed in the hair matrix and outer and inner root sheaths of anagen HFs. During catagen, Eda A1 mRNA and Edar protein were expressed in the outer and inner root sheaths and later in the secondary hair germ. Catagen development accompanied by increased apoptosis in the outer root sheath was significantly accelerated in downless mice or after treatment of wild-type mice by a fusion protein that inhibits Edar signaling, compared with the corresponding controls. Microarray, real-time polymerase chain reaction, and immunohistochemical analyses of skin of downless mice revealed a strong decrease of expression of X-linked inhibitor of apoptosis protein (XIAP), compared with the controls, suggesting XIAP as a target for Edar signaling. Thus, our data demonstrate that in addition to its well-established role in HF morphogenesis, Edar signaling is also involved in hair cycle control and regulates apoptosis in HF keratinocytes during catagen.
PMID: 17148670 [PubMed - indexed for MEDLINE]
The role of ectodysplasin in hair development:
http://ghr.nlm.nih.gov/gene=eda
(maybe this gene set being active in a particular way along with a particular variant of the AR-gene are what is necessary for male pattern baldness-to be inherited. I wonder if they can "block" what is necessary in pregnant mothers someday----not that this will help us)
Reviewed August 2006
What is the official name of the EDA gene?
The official name of this gene is “ectodysplasin A.â€
EDA is the gene's official symbol. The EDA gene is also known by other names, listed below.
What is the normal function of the EDA gene?
The EDA gene provides instructions for making a protein called ectodysplasin A. This protein is part of a signaling pathway that plays an important role in development before birth. Specifically, it is critical for interactions between two embryonic cell layers called the ectoderm and the mesoderm. In the early embryo, these cell layers form the basis for many of the body's organs and tissues. Ectoderm-mesoderm interactions are essential for the formation of several structures that arise from the ectoderm, including the skin, hair, nails, teeth, and sweat glands.
The EDA gene provides instructions for producing many slightly different versions of ectodysplasin A. One version, ectodysplasin A1, interacts with a protein called the ectodysplasin A receptor (produced from the EDAR gene). On the cell surface, ectodysplasin A1 attaches to this receptor like a key in a lock. When these two proteins are connected, they trigger a series of chemical signals that affect cell activities such as division, growth, and maturation. Before birth, this signaling pathway controls the formation of ectodermal structures such as hair follicles, sweat glands, and teeth.
How are changes in the EDA gene related to health conditions?
hypohidrotic ectodermal dysplasia - caused by mutations in the EDA gene
More than 80 different mutations in the EDA gene have been identified in people with hypohidrotic ectodermal dysplasia. These mutations cause the X-linked form of the disorder, which accounts for 95 percent of all cases of hypohidrotic ectodermal dysplasia. (X-linked disorders are caused by mutations in genes on the X chromosome, one of the two sex chromosomes.)
Some mutations in the EDA gene change single DNA building blocks (base pairs), whereas other mutations insert or delete genetic material in the gene. These changes lead to the production of a nonfunctional version of the ectodysplasin A protein. This abnormal protein cannot trigger chemical signals needed for normal interactions between the ectoderm and the mesoderm. Without these signals, hair follicles, teeth, sweat glands, and other ectodermal structures do not form properly, leading to the characteristic features of hypohidrotic ectodermal dysplasia.
Where is the EDA gene located?
Cytogenetic Location: Xq12-q13.1
Molecular Location on the X chromosome: base pairs 68,752,635 to 69,176,046
The first one is another recent genetic study which shows that a polymorphism in the ectodysplasin-A receptor gene is what gives Asians thick hair. The second study shows that ectodysplasin helps control the switch from anagen to catagen (early termination of anagen -- short growth cycles -- are a feature of male pattern baldness). Gene therapy for baldness would be really, really nice if it happens someday.
Hum Mol Genet. 2008 Mar 15;17(6):835-43.
A scan for genetic determinants of human hair morphology: EDAR is associated with Asian hair thickness.
Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Hongo, Tokyo, Japan.
Hair morphology is one of the most differentiated traits among human populations. However, genetic backgrounds of hair morphological differences among populations have not been clarified yet. In addition, little is known about the evolutionary forces that have acted on hair morphology. To identify hair morphology-determining genes, the levels of local genetic differentiation in 170 genes that are related to hair morphogenesis were evaluated by using data from the International HapMap project. Among highly differentiated genes, ectodysplasin A receptor (EDAR) harboring an Asian-specific non-synonymous single nucleotide polymorphism (1540T/C, 370Val/Ala) was identified as a strong candidate. Association studies between genotypes and hair morphology revealed that the Asian-specific 1540C allele is associated with increase in hair thickness. Reporter gene assays suggested that 1540T/C affects the activity of the downstream transcription factor NF-kappaB. It was inferred from geographic distribution of 1540T/C and the long-range haplotype test that 1540C arose after the divergence of Asians from Europeans and its frequency has rapidly increased in East Asian populations. These findings lead us to conclude that EDAR is a major genetic determinant of Asian hair thickness and the 1540C allele spread through Asian populations due to recent positive selection.
PMID: 18065779 [PubMed - in process]
Involvement of the Edar signaling in the control of hair follicle involution (catagen).
Department of Dermatology, Boston University School of Medicine, 609 Albany St., Boston, MA 02118, USA.
Ectodysplasin (Eda) and its receptor (Edar) are required for normal development of several ectodermal derivatives including hair follicles (HFs). Here, we show that during the murine hair cycle the expression of Eda A1, Edar, Edaradd, and TRAF6 transcripts are minimal in the resting phase and maximal during HF transition from active growth to regression (catagen). Eda A1 mRNA and Edar proteins were expressed in the hair matrix and outer and inner root sheaths of anagen HFs. During catagen, Eda A1 mRNA and Edar protein were expressed in the outer and inner root sheaths and later in the secondary hair germ. Catagen development accompanied by increased apoptosis in the outer root sheath was significantly accelerated in downless mice or after treatment of wild-type mice by a fusion protein that inhibits Edar signaling, compared with the corresponding controls. Microarray, real-time polymerase chain reaction, and immunohistochemical analyses of skin of downless mice revealed a strong decrease of expression of X-linked inhibitor of apoptosis protein (XIAP), compared with the controls, suggesting XIAP as a target for Edar signaling. Thus, our data demonstrate that in addition to its well-established role in HF morphogenesis, Edar signaling is also involved in hair cycle control and regulates apoptosis in HF keratinocytes during catagen.
PMID: 17148670 [PubMed - indexed for MEDLINE]
The role of ectodysplasin in hair development:
http://ghr.nlm.nih.gov/gene=eda
(maybe this gene set being active in a particular way along with a particular variant of the AR-gene are what is necessary for male pattern baldness-to be inherited. I wonder if they can "block" what is necessary in pregnant mothers someday----not that this will help us)
Reviewed August 2006
What is the official name of the EDA gene?
The official name of this gene is “ectodysplasin A.â€
EDA is the gene's official symbol. The EDA gene is also known by other names, listed below.
What is the normal function of the EDA gene?
The EDA gene provides instructions for making a protein called ectodysplasin A. This protein is part of a signaling pathway that plays an important role in development before birth. Specifically, it is critical for interactions between two embryonic cell layers called the ectoderm and the mesoderm. In the early embryo, these cell layers form the basis for many of the body's organs and tissues. Ectoderm-mesoderm interactions are essential for the formation of several structures that arise from the ectoderm, including the skin, hair, nails, teeth, and sweat glands.
The EDA gene provides instructions for producing many slightly different versions of ectodysplasin A. One version, ectodysplasin A1, interacts with a protein called the ectodysplasin A receptor (produced from the EDAR gene). On the cell surface, ectodysplasin A1 attaches to this receptor like a key in a lock. When these two proteins are connected, they trigger a series of chemical signals that affect cell activities such as division, growth, and maturation. Before birth, this signaling pathway controls the formation of ectodermal structures such as hair follicles, sweat glands, and teeth.
How are changes in the EDA gene related to health conditions?
hypohidrotic ectodermal dysplasia - caused by mutations in the EDA gene
More than 80 different mutations in the EDA gene have been identified in people with hypohidrotic ectodermal dysplasia. These mutations cause the X-linked form of the disorder, which accounts for 95 percent of all cases of hypohidrotic ectodermal dysplasia. (X-linked disorders are caused by mutations in genes on the X chromosome, one of the two sex chromosomes.)
Some mutations in the EDA gene change single DNA building blocks (base pairs), whereas other mutations insert or delete genetic material in the gene. These changes lead to the production of a nonfunctional version of the ectodysplasin A protein. This abnormal protein cannot trigger chemical signals needed for normal interactions between the ectoderm and the mesoderm. Without these signals, hair follicles, teeth, sweat glands, and other ectodermal structures do not form properly, leading to the characteristic features of hypohidrotic ectodermal dysplasia.
Where is the EDA gene located?
Cytogenetic Location: Xq12-q13.1
Molecular Location on the X chromosome: base pairs 68,752,635 to 69,176,046
