Disorders of sexual development are among the most common form of birth defects in humans (1 in 4,000 births) because failure of the gonads to develop does not affect the viability of the individual. Such disorders can have profound psychological and medical consequences upon the individual, family, and society. Some intersexual conditions are the result of inappropriate exposure to hormones during fetal life, and others are due to spontaneous or inherited gene mutation. About 5-10% of ovarian c ....Disorders of sexual development are among the most common form of birth defects in humans (1 in 4,000 births) because failure of the gonads to develop does not affect the viability of the individual. Such disorders can have profound psychological and medical consequences upon the individual, family, and society. Some intersexual conditions are the result of inappropriate exposure to hormones during fetal life, and others are due to spontaneous or inherited gene mutation. About 5-10% of ovarian cancer cases, that affect 1 in 8000 Australian women, are due to the inheritance of a faulty gene. An understanding of the way gene expression and hence tissue differentiation is altered after sex reversal will inform us about the causes and consequences of normal and abnormal sexual development, gonadal malignancies and infertility. The gonad is unusual in that two completely different organs can arise from an essentially identical primordium, so that errors in development lead to intersexual phenotypes. We will use our new experimental animal model to clarify these processes.Read moreRead less
Hypospadias is one of the most common developmental defects in humans, yet over two thirds of the cases cannot be explained. Our recent studies using marsupials show that this process is mediated by 5-alpha-androstanediol, a hormone with previously undetermined physiological function. This study will provide novel data on the interactions of the genes and hormones that will inform our understanding of this common developmental defect of male development
MicroRNA Regulation Of Sex Determination And Gonad Development.
Funder
National Health and Medical Research Council
Funding Amount
$518,076.00
Summary
Sex determination, the decision to develop into either boy or girl, influences most aspects of our lives. Consequently, disorders of sexual development (~1% of births), resulting in genital abnormalities, infertility and often cancer, are extremely traumatic for the individual. The molecular basis of these disorders is not well understood. This project will identify new factors important for sex determination and therefore will improve diagnosis and clinical care for the patients.
Much of our current knowledge on development of external genitalia (ExG), the penis and clitoris, comes from 20 &70 year-old studies (1); but with significant developments in contemporary imaging and new mouse models, we have new data. The overall goal of this project is to prove the hypothesis that penile and clitoral development is estrogen- (and androgen-) dependent and, to show that the administration of exogenous endocrine disrupting chemicals that alter the balance between estrogen and and ....Much of our current knowledge on development of external genitalia (ExG), the penis and clitoris, comes from 20 &70 year-old studies (1); but with significant developments in contemporary imaging and new mouse models, we have new data. The overall goal of this project is to prove the hypothesis that penile and clitoral development is estrogen- (and androgen-) dependent and, to show that the administration of exogenous endocrine disrupting chemicals that alter the balance between estrogen and androgen will disrupt ExG development.Read moreRead less
Impairment of virilisation is one of the most common developmental defects in humans, yet over half the cases cannot be explained by our current knowledge. Studies of these processes is hindered because in most mammals virilisation occurs in the early fetus. Our recent studies using marsupials, where virilisation occurs after birth show that this process is mediated by 5-alpha-androstanediol, a hormone with previously undetermined physiological function. We will conduct experiments using tammar ....Impairment of virilisation is one of the most common developmental defects in humans, yet over half the cases cannot be explained by our current knowledge. Studies of these processes is hindered because in most mammals virilisation occurs in the early fetus. Our recent studies using marsupials, where virilisation occurs after birth show that this process is mediated by 5-alpha-androstanediol, a hormone with previously undetermined physiological function. We will conduct experiments using tammar wallabies and rabbits, to test 3 hypotheses about 5-alpha-androstanediol and specific enzymes in the developing reproductive tissues that either convert this hormone to active and inactive forms. The results of these experiments will direct testing for corresponding gene mutations in our collection of over 200 specimens from patients with defects of virilisation (pseudohemaphroditism) whose causes are still unknown. It is our expectation that the findings in these studies will provide insight not only into the pathways by which testicular hormones masculinize the developing male, but will also explain instances of male pseudohemaphroditism of unknown aetiology in humans.Read moreRead less
New Models For The Onset Of Virilisation In The Developing Male
Funder
National Health and Medical Research Council
Funding Amount
$405,750.00
Summary
Impairment of virilisation is one of the most common developmental defects in humans, yet over half the cases cannot be explained by our current knowledge. Studies of these processes are hindered because in most mammals virilisation occurs in utero, in the early fetus. Our recent studies using marsupials, where virilisation occurs after birth show that this process is mediated by 5-alpha-androstanediol, a hormone with previously undetermined physiological function. We will conduct experiments us ....Impairment of virilisation is one of the most common developmental defects in humans, yet over half the cases cannot be explained by our current knowledge. Studies of these processes are hindered because in most mammals virilisation occurs in utero, in the early fetus. Our recent studies using marsupials, where virilisation occurs after birth show that this process is mediated by 5-alpha-androstanediol, a hormone with previously undetermined physiological function. We will conduct experiments using tammar wallabies, to test hypotheses that explain why different male tissues - such as the reproductive ducts, prostate and penis - start to differentiate at widely different times. We will investigate pathways of androgen formation and the activation and inactivation of hormones in the target organs, and the role of hormone binding proteins. We will also investigate the role of growth factors that may mediate growth of the penis during early development. The results of these experiments will direct funding in subsequent years to test for corresponding gene mutations in our collection of over 200 specimens from patients with defects of virilization (pseudohermaphroditism) whose causes are still unknown. It is our expectation that the findings in these studies will provide insight not only into the pathways by which testicular hormones masculinize the developing male, but will also explain instances of male pseudohermaphroditism of unknown aetiology in humans.Read moreRead less
Defects of the internal and external genitalia are among the most common birth defects in babies (1 in 4,000 births) yet the aetiology in many cases is unclear. We will compare and contrast the mouse with a unique animal model the tammar wallaby to investigate the control of ovarian differentiation during early fetal and postnatal life. The gonad is unusual in that two completely different organs arise from the same precursor tissues, so that errors in development lead to intersexual phenotypes. ....Defects of the internal and external genitalia are among the most common birth defects in babies (1 in 4,000 births) yet the aetiology in many cases is unclear. We will compare and contrast the mouse with a unique animal model the tammar wallaby to investigate the control of ovarian differentiation during early fetal and postnatal life. The gonad is unusual in that two completely different organs arise from the same precursor tissues, so that errors in development lead to intersexual phenotypes. Some intersexual conditions are the result of inappropriate exposure to hormones during fetal life, and others are due to spontaneous or inherited gene mutations. About 5-10% of ovarian cancer cases, that affect 1 in 8000 Australian women, are due to the inheritance of a faulty gene. We will use comparative analysis and an inducible sex reversal system to understand the way gene expression and hence tissue differentiation is altered between male and female during the formation of the ovary versus the testis. This will inform us about the causes and consequences of normal and abnormal sexual development, infertility and gonadal malignancies.Read moreRead less