Editing Disorders of Sexual Differentiation (section)

==== Turner syndrome ====
* '''Karyotype: 45X'''
** '''Presence of only one normally functioning X chromosome; the other sex chromosome may be absent or abnormal, or mosaicism may be present'''
* '''Clinical characteristics:'''
** '''Female phenotype'''
** '''Short stature'''
** '''Lymphedema'''
*** Majority of the associated congenital anomalies can be explained by the presence of lymphedema at critical points in development, leading to an imbalance in growth forces
** '''Broad chest, webbed neck''', widespread nipples, cubitus valgus (increased carrying angle at the elbows), peripheral edema at birth, short fourth metacarpal, hypoplastic nails, multiple pigmented nevi
** '''Primary amenorrhea'''
*** '''Common cause of primary amenorrhea, and the diagnosis is frequently made because pubertal development never occurs'''
** '''Lack of secondary sexual characteristics'''
*** Pubic and axillary hair fails to develop in normal abundance, and the well-differentiated external genitalia, vagina, müllerian derivatives, and breasts remain small
** '''Gonadal dysgenesis'''
*** '''Ovaries become streaks and are located in the broad ligament'''
**** Histologically, the hypoplastic streak possesses interlacing waves of dense fibrous stroma that is devoid of oocytes but is otherwise indistinguishable from normal ovarian stroma.
*** '''Both estrogen and androgen are decreased, and levels of FSH and LH are increased'''
** '''Coarctation of the aorta, bicuspid aortic valve, and renal anomalies'''
*** 33-60% have structural or positional abnormalities of the kidney such as '''horseshoe kidney,''' duplication or renal agenesis, and malrotation
** Neurophysiologic and cognitive deficits
*** Differences in parietal and temporal lobe anatomy and posterior fossa morphology
* Diagnosis and Evaluation
** May be diagnosed prenatally on the basis of a variety of ultrasound findings (increased nuchal translucency, lymphedema, cystic hygroma, coarctation of the aorta, renal anomalies) or by abnormal results of fetal karyotyping.
* '''Management'''
** '''Must identify possible Y-chromosomal material or 45X/46XY mosaicism'''
*** Occult Y-chromosomal material in the neonate is evaluated with fluorescence in situ hybridization (FISH) or PCR
*** '''Risk of gonadoblastoma (in situ germ cell cancer of low malignant potential) with occult Y-chromosomal material: 12%'''
**** '''Gonadoblastoma is associated with dysgerminoma or other germ cell neoplasms'''
*** '''Because the age of occurrence of gonadoblastoma is variable and has been reported as early as age 10 months, timely prophylactic excision of the streak gonads in the Y mosaic Turner syndrome patient is advised'''
*** '''Streak gonads in confirmed 45,XO patients (without any Y-chromosome material) do not need to be removed'''
** Ultrasound screening for renal and cardiac abnormalities
** Human growth hormone has successfully been used in children to achieve increased adult height.
** At an appropriate age, typically 12-15 years, exogenous hormonal therapy to induce puberty and then to maintain a normal female endocrine status is begun.
*** '''A spectrum of potential gonadal function has been noted in large series of patients with Turner syndrome. In 2-5% of Turner patients, spontaneous menses will occur with a potential to achieve pregnancy independently, although spontaneous fertility is rare.'''
** Because of a high likelihood of premature ovarian failure, early oocyte preservation may be useful for long-term fertility preservation.
** Turner syndrome patients are at increased risk of bladder and urethral cancer