10 terms

Disorders of Sex Development - Repro - USMLE Step 1

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Klinefelter syndrome
(47,XXY)

Testicular atrophy, eunuchoid body shape, tall, long extremities, gynecomastia, female hair distribution. May present with developmental delay. Presence of inactivated X chromosome (barr body). Common cause of hypogonadism seen in infertility work-up.

Labs:
Decreased Inhibin
Increased FSH
Decreased testosterone
Increased LH
Increased estrogen
Turner Syndrome
(45,XO) or mosaicism (e.g. 45,XO/46,XX)

Short stature (if untreated), ovarian dysgenesis (streak ovary), shield chest, bicuspid aortic valve, preductal coarctation (femoral < brachial pulse), lymphatic defects (result in webbed neck or cystic hygroma; lymphedema in feet, hands), horseshoe kidney. Most common cause of primary amenorrhea. No barr body.

Labs:
Decreased estrogen
Increased LH
Increased FSH
Double Y males
(XYY)

Phenotypically normal (usually undiagnosed), very tall. Random nondisjunction event (paternal meiosis II); noninherited; normal fertility. May be associated with severe acne, learning diability, autism spectrum disorders, and antisocial personality disorder.
True hermaphroditism
(46,XX) or (47,XXY)

Also called ovotestitular disorder of sex development. Both ovarian and testicular tissue present (ovotestis); ambiguous genitalia.
Female pseudohermaphroditism
(46,XX)

Ovaries present, but external genitalia are virilized or ambiguous. Due to excessive and inappropriate exposure to androgenic steroids during early gestation (e.g. congenital adrenal hyperplasia or exogenous administration of androgens during pregnancy).

Labs:
Increased testosterone
Decreased LH
Aromatase deficiency
(46,XX)

Inability to synthesize estrogens from androgens. Masculinization of female infants (ambiguous genitalia). Can present with maternal virilization during pregnancy (fetal androgens cross the placenta).

Labs:
Increased testosterone
Increased androstenedione
Male pseudohermaphroditism
Testes present, but external genitalia are female or ambiguous. Most common form is androgen insensitivity syndrome (testicular feminization).
Androgen insensitivity syndrome
(46,XY)

Defect in androgen receptor resulting in normal-appearing female; female external genitalia with scant sexual hair, rudimentary vagina (urogenital sinus forms lower 2/3 of vagina but, due to presence of MIF, upper 1/3 and other more proximal structures are absent --> uterus and fallopian tubes absent). Patients develop testes (often found in the labia majora); surgically removed to prevent malignancy.

Labs:
Increased testosterone
Increased estrogen
Increased LH
5-alpha-reductase deficiency
(46,XY)

Autosomal recessive; Inability to convert testosterone to DHT. Ambiguous genitalia until puberty, when increased testosterone causes masculinization/increased growth of external genitalia. Normal internal genitalia.

Labs:
NORMAL testosterone/estrogen
Increased or NORMAL LH
Kallmann syndrome
Failure to complete puberty; a forms of hypogonadotropic hypogonadism. Defective migration of GnRH cells and formation of olfactory bulb; decreased synthesis of GnRH in the hypothalamus; anosmia. Defect of X-linked KAL chain. Infertility (low sperm count in males; amenorrhea in females).

Labs:
Decreased GnRH
Decreased FSH
Decreased LH
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