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TURNER SYNDROME (TS)
XO syndrome, monosomyX
Turner syndrome (TS) was first described in 1938, when Dr. Henry Turner
syndrome (TS) is a chromosomal disorder that affects females and is caused by a
complete or partial loss of the second sex-determining chromosome. The syndrome
is typically characterized by short stature, ovarian insufficiency, and malformations
in organ systems that could include cardiac defects (particularly coarctation of the
aorta and bicuspid aortic valve), lymphedema (especially nuchal and over the
dorsum of the hands and feet), short 4th metacarpals, and genitourinary
malformations (such as horseshoekidney). Some affected individuals are
phenotypically normal females with only short stature. Others can have life-
threatening cardiovascular, hormonal, and lymphatic anomalies or manifestations,
such as short stature, pubertal delay, and sterility, which impart significant psycho-
emotional burden and a higher risk for co-morbidities.
TS is present in approximately 1 in 2000 to 2500 live female births worldwide.
Prevalence is greater if pregnancies that do not survive to term are taken into
Types of chromosomalanomalies associated with TS
1. 45, X (monosomy X) is found in approximately 45% of live births with TS; these
patients should be evaluated for presence of Y chromosomematerial.
2. 45, X mosaicism is a mosaic chromosomal complement (e.g., 45,X/46,XX)
detectable in 20-30% of all patients with TS.
3. X chromosomeanomalies:
About half of women with TS are completely missing the second sex chromosome;
in the other half, it may be partially missing or rearranged. Mosaic TS occurs when
only some of the individual’s cells lack the second normal sex chromosome. The
severity of the phenotype is related to the absence or presence of a second sex
chromosome. Full monosomy(45,X or 45,XO) typically is the most severe form
and mosaic TS is typically the mildest form.
The SHOX gene plays a large role in determining height and bone growth. It is
located on the X chromosomein both men and women. When all or part of an X
chromosomeis missing, so is the SHOX gene. This accounts for the short stature
commonly associated with Turner syndrome.
Unexplained growth failure
Nuchal redundancy, cystic hygroma
Widely spaced nipples, perhaps with shield chest and pectus excavatum
Cystic hygromalymphedema sequence (edema of hands or feet, webbed
neck, low hairline, hyperconvex and hypoplastic nails)
Cardiac anomalies, such as bicuspid aortic valve, coarctation of aorta
Multiple pigmented nevi
Short fourth metacarpal bones
In childhood and adolescence
Short stature (in nearly 100%)
Chronic otitis media
Hyperconvex, narrow fingernails; thin,
mildly dysplastic toenails
I. History collection
II. Physical examination
III. Sensory Testing
An audiologist should perform a hearing evaluation at diagnosis and every 3-5
years thereafter. If there is a history of otitis media or hearing loss, evaluations are
usually performed annually.
TS is associated with red-green color blindness (10%), hyperopia (35%), and
strabismus (25%) with risk of amblyopia. Girls with TS should be evaluated by a
pediatric ophthalmologist by 12-18 months of age or earlier if clinically indicated.
If initial evaluation is normal, the medical home provider should conductannual
routine vision screening.
IV. Laboratory Testing
a) Assess thyroid function with a TSH and T4.
b) Screen for celiac disease with a tissue transglutaminase iga (TTG) and
total serum iga.
c) Perform hepatic function panel, GGT, hba1c with or without fasting
plasma glucose, fasting lipid panel.
d) 25-hydroxyvitamin D
VI. Genetic Testing
a) Growth hormone therapy to achieve greater height,
b) Estrogen replacement therapy to mimic natural estrogen.
c) Reproductive technologies have also been used to help women with Turner
syndrome become pregnant if they desire.