PATH - Sex chromosome disorders

Question 1

Klinefelter syndrome

Answer 1

47,XXY (male)

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

Question 2

Turner syndrome

Answer 2

45,XO (female)

Short stature, ovarian dysgenesis (*streak ovary), shield chest, bicuspid aortic
valve, coarctation (femoral

Question 3

Double Y males

Answer 3

XYY

Phenotypically normal,
very tall

Normal fertility

May be associated with severe acne, learning disability, autism spectrum disorders.

Ass. w/ personality and prison inmates

Question 4

Ovotesticular disorder of sex development

Answer 4

46,XX > 46,XY

Both ovarian and testicular tissue present (ovotestis)

ambiguous genitalia.

AKA true hermaphroditism

Question 5

46,XX DSD

Disorder of sex development

Answer 5

Ovaries present, but external genitalia are virilized or ambiguous.

Due to excessive and
inappropriate exposure to androgenic steroids during early gestation

Question 6

46,XY DSD

Answer 6

Testes present, but external genitalia are female or ambiguous

Most common form is *androgen insensitivity syndrome (testicular feminization).

Question 7

Placental aromatase deficiency

Answer 7

Inability to synthesize estrogens from androgens

Masculinization of female (46,XX) infants (ambiguous genitalia)

INC serum testosterone and androstenedione

Can present with *maternal
virilization during pregnancy (fetal androgens cross the placenta).

Question 8

Androgen insensitivity

syndrome

Answer 8

46,XY

Defect in androgen receptor resulting in normal-appearing female

female external genitalia with scant sexual hair, rudimentary vagina

*uterus and fallopian tubes absent

Patients develop normal
functioning testes (often found in labia majora; surgically removed to prevent malignancy)

INC testosterone, estrogen, LH

Question 9

5 -reductase deficiency

Answer 9

Autosomal recessive

sex limited to genetic males (46,XY)

Inability to convert testosterone to DHT

Ambiguous genitalia until puberty, when INC testosterone causes masculinization/INC growth of external genitalia

Internal genitalia are normal

Testosterone/estrogen levels are normal

LH is normal or INC

Question 10

Kallmann syndrome

Answer 10

Failure to complete puberty

form of *hypogonadotropic hypogonadism

Defective migration of
GnRH cells and formation of olfactory bulb

DEC synthesis of GnRH in the hypothalamus; *anosmia

DEC GnRH, FSH, LH, testosterone

*Infertility (low sperm count in males; amenorrhea in females).