Swyer syndrome 563400 223214128 2008-07-03T02:20:19Z Arcadian 104523 nav {{Infobox_Disease | Name = {{PAGENAME}} | Image = | Caption = | DiseasesDB = 31464 | ICD10 = {{ICD10|Q|56|4|q|50}}| ICD9 = {{ICD9|752.7}} | ICDO = | OMIM = 306100 | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | MeshID = D006061 | }} '''Swyer syndrome''', or '''XY gonadal dysgenesis''', is a type of female [[hypogonadism]] in which no functional [[gonad]]s are present to induce [[puberty]] in an otherwise normal girl whose [[karyotype]] is then found to be XY. Her [[gonad]]s are found to be nonfunctional [[streak gonads|streaks]]. [[Estrogen]] and [[progesterone]] therapy is usually then commenced. The gonads are normally removed surgically because they do not function and may develop [[cancer]]. == Swyer syndrome as a form of "pure gonadal dysgenesis"== There are several forms of [[gonadal dysgenesis]]. The term “pure gonadal dysgenesis” (PGD) has been used to describe conditions with normal sets of sex chromosomes (e.g., 46,XX or 46,XY), as opposed to those whose gonadal dysgenesis results from missing all or part of the second sex chromosome. The latter group includes those with [[Turner syndrome]] (e.g., 45,X) and its variants, as well as those with [[mixed gonadal dysgenesis]] and a mixtures of cell lines, some containing a Y chromosome (e.g., 46,XY/45,X). Thus Swyer syndrome is referred to as PGD, 46,XY, and [[XX gonadal dysgenesis]] as PGD, 46,XX.<ref>[http://www.medscape.com/viewarticle/499501_5 Specific Disorders of Ambiguous Genitalia]</ref> Patients with PGD have a normal chromosomal constellation but may have defects of a specific gene on a chromosome. == 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 [[gene]]s, of which one of the earliest and most important is ''[[SRY]]'', the "sex-determining region of the Y chromosome". Mutations of SRY account for many cases of Swyer syndrome. When such a gene is defective, the [[Development of the gonads#Before differentiation|indifferent gonads]] fail to differentiate into [[testes]], in an XY (genetically male) fetus. Without testes, no [[testosterone]] or [[antimullerian hormone|antimullerian hormone (AMH)]] are produced. Without [[testosterone]] the external [[genitalia]] fail to [[virilization|virilize]], resulting in normal female genitalia, and the [[wolffian duct]]s fail to develop, so no internal male organs are formed. Without AMH, the [[mullerian duct]]s develop into normal internal female organs ([[uterus]], [[fallopian tube]]s, [[cervix]], [[vagina]]). A baby girl is born who is normal in all anatomic respects except that she has nonfunctional [[streak gonads]] instead of [[ovary|ovaries]] or testes. As girls' ovaries normally produce no important body changes before [[puberty]], a defect of the reproductive system typically remains unsuspected in girls with Swyer syndrome until puberty fails to occur. == Diagnosis == Because of the inability of the streak gonads to produce [[sex hormone]]s (both [[estrogen]]s and [[androgen]]s), most of the [[secondary sex characteristic]]s do not develop. This is especially true of estrogenic changes such as breast development, widening of the pelvis and hips, and [[menstrual cycle|menstrual periods]]. Because the [[adrenal gland]]s 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. Evaluation of [[delayed puberty]] usually reveals elevation of [[gonadotropin]]s, 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). Although an XY karyotype can also indicate a girl with complete [[androgen insensitivity syndrome]], the absence of breasts, and the presence of a uterus and pubic hair exclude the possibility. At this point it is usually possible for a physician to make a diagnosis of Swyer syndrome. == Treatment == The consequences of streak gonads to a woman with Swyer syndrome: # Gonads cannot make estrogen, so the breasts will not develop and the uterus will not grow and menstruate until [[estrogen]] is administered. This is often given through the skin now. # Gonads cannot make progesterone, so menstrual periods will not be predictable until [[progestin]] is administered, still usually as a pill. # Gonads cannot produce [[ovum|eggs]] so conceiving children naturally is not possible. A woman with a uterus but no ovaries may be able to become pregnant by implantation of another woman's fertilized egg ([[embryo transfer]]). # Streak gonads with Y chromosome-containing cells have a high likelihood of developing cancer, especially [[gonadoblastoma]]. Streak gonads are usually removed within a year or so of diagnosis since the cancer can begin during infancy. == Gonadal dysgenesis and other similar or related conditions == Swyer syndrome represents one [[phenotype|phenotypic]] result of a failure of the gonads to develop properly, and hence is part of a class of conditions termed [[gonadal dysgenesis]]. There are many forms of gonadal dysgenesis. Swyer syndrome is an example of a condition in which an externally unambiguous female body carries dysgenetic, atypical, or abnormal gonads. Other examples include complete [[androgen insensitivity syndrome]], partial [[X chromosome]] deletions, [[lipoid congenital adrenal hyperplasia]], and [[Turner syndrome]]. ==References== <references/> == External links == * [http://www-personal.umd.umich.edu/~jcthomas/JCTHOMAS/1997%20Case%20Studies/N.Justus.html Gonadal dysgenesis] * [http://www.acta-endo.ro/archive/2006/numarul4/abstracts/Complete%20Gonadal%20Dysgenesis%20With%20XY%20Chromosomal%20Constitution.html Swyer Syndrome Case Report] {{Congenital malformations of genital organs and urinary system}} [[Category:Intersexuality]] [[Category:Syndromes]] [[Category:Gynecology]] [[de:Swyer-Syndrom]] [[pl:zespół Swyera]]