TURNER SYNDROME
Turner syndrome only affects females. It is also called monosomy X, and it results
from having only one copy of chromosome X.
Genetically, Turner syndrome can often arise from nondisjunction errors occurring in
meiosis. Nondisjunction of the sex chromosomes during meiosis I and II can result in
gametes that do not have any sex chromosomes. When such a sex-chromosome
“empty” gamete combines with an X chromosome, this results in an embryo with an
“XO” genotype.
Monosomy resulting from
• nondisjuction (XO)
• mosaicism (XX, XO; XY, XO)
• only monosomy not aborted in utero
• no Barr bodies
PHYSICAL EXAMINATION
• SHORT STATURE
• WEBBED NECK
• SHIELD CHEST
• WRIST AND ANKLE EDEMA
• CUBITUS VALGUS
• PTOSIS, HYPERTELORISM
• RETROGNATHISM
Pathogenesis:
Decreased estradiol, increased FSH, LH
Normal GH, IGF-1 levels
Turner syndrome only affects females. It is also called monosomy X, and it results
from having only one copy of chromosome X.
Genetically, Turner syndrome can often arise from nondisjunction errors occurring in
meiosis. Nondisjunction of the sex chromosomes during meiosis I and II can result in
gametes that do not have any sex chromosomes. When such a sex-chromosome
“empty” gamete combines with an X chromosome, this results in an embryo with an
“XO” genotype.
Monosomy resulting from
• nondisjuction (XO)
• mosaicism (XX, XO; XY, XO)
• only monosomy not aborted in utero
• no Barr bodies
PHYSICAL EXAMINATION
• SHORT STATURE
• WEBBED NECK
• SHIELD CHEST
• WRIST AND ANKLE EDEMA
• CUBITUS VALGUS
• PTOSIS, HYPERTELORISM
• RETROGNATHISM
Pathogenesis:
Decreased estradiol, increased FSH, LH
Normal GH, IGF-1 levels
