Mehl. + UW Tuner syndrome Flashcards
Mehl. What karyotype is associated with a female phenotype in Turner syndrome?
45XO karyotype
This indicates the presence of a single X chromosome and no second sex chromosome.
Mehl. What is NOT visible on electron microscopy in a 45XO karyotype?
Barr body (Q can say that)
A Barr body is an inactivated X chromosome; in this case, it is absent due to the single X chromosome.
Mehl. What causes infertility in individuals with Turner syndrome?
Streak ovaries
Streak ovaries are non-functional ovaries that do not produce eggs.
Mehl. Infertile due to streak ovaries. In Turner, this is colloquially referred to as “menopause before menarche.”
.
This term highlights the premature ovarian failure experienced in Turner syndrome.
Mehl. can have kids through what method?
Mehl. Can still have children with IVF using donor egg + exogenous hormones (asked sometimes on behavioral/psych Qs).
.
Mehl. LH and FSH levels?
LH and FSH both incr. due to primary hypogonadism.
(i.e., ̄ negative-feedback at hypothalamus and anterior pituitary due to ̄ ovarian hormones and inhibin).
Mehl. stature?
Short stature (usually < 5 feet)
Mehl. breast tanner?
Tanner stage 1 breast development (“shield chest”),
Mehl. pubic hair tanner?
normal pubic and axillary hair (Tanner 4-5).
Mehl. finding in neck?
cystic hygroma (webbed neck due to lymphatic insufficiency; asked on NBME);
Mehl. Seen scattered nevi (confuses students for things like NF1, but I don’t know what to say; you need to know scattered nevi are seen in Turner);
Mehl. incr. risk for what? reproductive
Incr. risk of dysgerminoma developing from the streak ovaries;
Mehl. what is recommended to prevent dysgerminoma from streak ovaries?
prophylactic oophorectomy is recommended, especially if there is Y-chromosome material present in rarer mosaic forms of Turner
Mehl. If Q tells you there’s a fraction of a female’s cells that are 46XX and another fraction that’s 45XO (i.e., somatic mosaic Turner), the answer for the mechanism is?????
“post-fertilization mitotic error.”
Mehl. HY cardiac pathologies?2
Coarctation of the aorta + bicuspid aortic valve (aortic stenosis) HY.
UW. etiology?
Complete or partial loss of X chromosome
UW. CP in infancy? 2
Lymphedema, cystic hygroma
Renal and heart defects (horsehoe kidney, aortic coarctation, bicuspid aortic valve)
UW. CP in childhood? 2
Short stature
Dysmorphic features: webbed neck, broad chest, high-arched palate, cubitus vagus, short 4th metacarpal
UW. CP in adolescnece? 2
Delayed tenarche
Amenorrhea (primary or secondary)
UW. Dx?2
Karyotype (45X)
Comorbidity screenin (cardiac and renal imaging)
UW. Tx?
groth hormone and estrogen (+/- progestin) therapy
UW. definition of short stature?
height ≥2 standard deviations below the mean or ≤2nd percentile for age.
UW. why patients have short stature?
SHOX (short stature homeobox) gene is contained on the X chromosome
UW. why gonadal insuf.?
Gonadal insufficiency is due to replacement of ovarian follicles by connective tissue (“streak ovaries”) and becomes apparent in adolescence (eg, absent breast development, primary amenorrhea).
UW. treatment is recombinant growth hormone when height falls <5th percentile to maximize linear growth potential.
.
UW. kitas variantas: Estradiol therapy is initiated around age 11 to induce puberty and breast development and reduce the risk for osteoporosis and associated cardiovascular complications
After menarche, progestin is typically added to mitigate endometrial hyperplasia risk.
