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Encyclopedia > Swyer syndrome
Swyer syndrome
ICD-10 code:
ICD-9 code: 752.7

Swyer syndrome, or XY gonadal dysgenesis, is a type of female hypogonadism in which no functional gonads are present to induce puberty in an otherwise normal girl whose karyotype is then found to be XY. Her gonads are found to be nonfunctional streaks. Estrogen and progesterone therapy is usually then commenced. The gonads are normally removed surgically because they do not function and may develop cancer. The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... Hypogonadism is a medical term for a defect of the reproductive system which results in lack of function of the gonads (ovaries or testes). ... The gonad is the organ that makes gametes. ... Puberty refers to the process of physical changes by which a childs body becomes an adult body capable of reproduction. ... Karyogram of human female A karyotype is the complete set of all chromosomes of a cell of any living organism. ... The gonad is the organ that makes gametes. ... Estrogens (also oestrogens) are a group of steroid compounds that function as the primary female sex hormone. ... Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ...

Contents


Pathogenesis

The first known step of sexual differentiation of a normal XY fetus is the development of testes. The early stages of testicular formation in the second month of gestation require the action of several genes, of which one of the earliest and most important is SRY, the "sex-determining region of the Y chromosome". Sexual differentiation is the process of development of the differences between males and females from an undifferentiated zygote (fertilized egg). ... Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... SRY is the sex-determining Y chromosome gene in humans and other primates, linked to determining males. ...


Mutations of SRY account for most cases of Swyer syndrome. When this gene is defective, testes fail to develop in an XY (genetically male) fetus. Without testes, no testosterone or antimullerian hormone are produced. Without testosterone the external genitalia fail to virilize, resulting in female genitalia. Without testosterone, the wolffian ducts fail to develop, so no internal male organs are formed. Without AMH the mullerian ducts develop into normal internal female organs (uterus, fallopian tubes, cervix, vagina). Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... Testosterone is a steroid hormone from the androgen group. ... Antimullerian hormone is a protein hormone produced by human and other mammalian gonads. ... Testosterone is a steroid hormone from the androgen group. ... A sex organ, or primary sexual characteristic, narrowly defined, is any of those parts of the body (which are not always bodily organs according to the strict definition) which are involved in sexual reproduction and constitute the reproductive system in an complex organism; namely: Male: penis (notably the glans penis... In biology and medicine, virilization refers to the development of changes which make a male body different from a female body. ... The Wolffian duct (also known as archinephric duct, Leydigs duct, and the mesonephric duct) is an paired organ found in mammals including humans during embryogenesis. ... Antimullerian hormone is a protein hormone produced by human and other mammalian gonads. ... The Müllerian ducts are paired ducts of the embryo which empty into the cloaca, and which in the female develop into the upper vagina, cervix, uterus and oviducts; in the male they disappear except for the vestigial vagina masculina and the appendix testis. ... Female internal reproductive anatomy The uterus or womb is the major female reproductive organ of most mammals, including humans. ... Female internal reproductive anatomy The Fallopian tubes or oviducts are two very fine tubes leading from the ovaries of female mammals into the uterus. ... Female internal reproductive anatomy Close up view of the ectocervix and external os Schematic frontal view of female anatomy The cervix (from Latin neck) is actually the lower, narrow portion of the uterus where it joins with the top end of the vagina. ... Complete external female genital anatomy Human female internal reproductive anatomy. ...


A baby girl is born who is normal in all anatomic respects except that she has nonfunctional streak gonads instead of ovaries or testes. As girls' ovaries produce no important body changes before puberty, there is usually no suspicion of a defect of the reproductive system until puberty fails to occur. Human female internal reproductive anatomy Ovaries are a part of a female organism that produces eggs. ... Puberty refers to the process of physical changes by which a childs body becomes an adult body capable of reproduction. ...


Diagnosis

Because of the inability of the streak gonads to produce sex hormones (both estrogens and androgens), most of the secondary sex characteristics do not develop. This is especially true of estrogenic changes such as breast development, widening of the pelvis and hips, and menstrual periods. Because the adrenal glands can make limited amounts of androgens and are not affected by this syndrome, most of these girls will develop pubic hair, though it often remains sparse. Sex hormones are hormones that affect the reproductive system. ... Estrogens (also oestrogens) are a group of steroid compounds that function as the primary female sex hormone. ... Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors. ... A peafowl displays its secondary sexual characteristics (long, colored feathers). ... Menstrual cycle The menstrual cycle is the set of recurring physiological changes in a females body that are under the control of the reproductive hormone system and necessary for reproduction. ... In mammals, the adrenal glands (also known as suprarenal glands or colloquially as kidney hats) are the triangle-shaped endocrine glands that sit atop the kidneys. ...


Evaluation of delayed puberty usually reveals the presence of pubic hair, but elevation of gonadotropins, indicating that the pituitary is providing the signal for puberty but the gonads are failing to respond. The next steps of the evaluation usually include checking a karyotype and imaging of the pelvis. The karyotype reveals XY chromosomes and the imaging demonstrates the presence of a uterus but no ovaries (the streak gonads are not usually seen by most imaging). At this point it is usually possible for a physician to make a diagnosis of Swyer syndrome. Puberty is described as delayed when a boy or girl has passed the usual age of onset of puberty with no physical or hormonal signs that it is beginning. ... Gonadotropins are protein hormones secreted by gonadotrope cells of the pituitary gland of vertebrates. ... Karyogram of human female A karyotype is the complete set of all chromosomes of a cell of any living organism. ...


Treatment

The consequences to the girl with Swyer syndrome of her streak gonads:

  1. Her gonads cannot make estrogen, so her breasts will not develop and her uterus will not grow and menstruate until she is given estrogen. This is often given through the skin now.
  2. Her gonads cannot make progesterone, so her menstrual periods will not be predictable until she is given a progestin, still usually as a pill.
  3. Her gonads cannot produce eggs so she will not be able to conceive children the natural way. A woman with a uterus but no ovaries may be able to become pregnant by implantation of another woman's fertilized egg (embryo transfer).
  4. Streak gonads with Y chromosome-containing cells have a high likelihood of developing cancer, especially gonadoblastoma. Rarely, this can begin as early as a few years of age, so the streak gonads are usually removed by surgery within a year or so after discovery of the diagnosis.

Estrogens (also oestrogens) are a group of steroid compounds that function as the primary female sex hormone. ... A progestin is a synthetic progestagen. ... A human ovum An ovum (loosely, egg or egg cell) is a female sex cell or gamete. ... Embryo transfer refers to a step in the process of in vitro fertilization (IVF) whereby one or several embryos are placed into the uterus of the female with the intent to establish a pregnancy. ...

Similar conditions

Swyer syndrome results from a failure of one of the earliest stages of differentiation of a genetic male: translation of the SRY gene to initiate testicular development. In a minority of cases of apparent Swyer syndrome, some other very early defect of testicular development (testicular dysgenesis) occurs. Since estrogens are made from androgens, any severe defect of androgen production (e.g., congenital adrenal hyperplasia due to 17 alpha-hydroxylase deficiency) will also produce estrogen deficiency and result in a failure of pubertal development in a girl with an XY karyotype. On the other hand, a defect of androgen action (e.g., androgen insensitivity syndrome) is readily distinguished because the breasts begin to develop normally without much delay, though pubic hair may be minimal. Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency is an uncommon form of congenital adrenal hyperplasia resulting from a defect in the gene for the enzyme P450c17, which mediates several key transformations in the synthesis of both cortisol and sex steroids. ... Androgen insensitivity syndrome (AIS) is a set of disorders of sexual differentiation that results from mutations of the gene encoding the androgen receptor. ...


External links

  • Androgen Insensitivy Syndrome (AIS) Support Group
  • Gonadal dysgenesis

  Results from FactBites:
 
Swyer syndrome - definition of Swyer syndrome in Encyclopedia (717 words)
Swyer syndrome, or XY gonadal dysgenesis, is a type of female hypogonadism in which no functional gonads are present to induce puberty in an otherwise normal girl whose karyotype is then found to be XY.
Swyer syndrome results from a failure of one of the earliest stages of differentiation of a genetic male: translation of the SRY gene to initiate testicular development.
On the other hand, a defect of androgen action (e.g., androgen insensitivity syndrome) is readily distinguished because the breasts begin to develop normally without much delay, though pubic hair may be minimal.
Swyer syndrome (645 words)
Swyer syndrome, or XY gonadal dysgenesis, is a type of female
adrenal glands can make limited amounts of androgens and are not affected by this syndrome, most of these girls will develop pubic hair, though it often remains sparse.
androgen insensitivity syndrome) is readily distinguished because the breasts begin to develop normally without much delay, though pubic hair may be minimal.
  More results at FactBites »

 
 

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