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TURNER SYNDROME (TS)

The diagnosis of TS requires the presence of characteristic  physical features (short stature, sexual infantalism and various somatic abnormalities)in phenotypic females  coupled with complete or partial absence of the second sex chromosome, with or without cell line mosaicism
 
Individuals with a 45,X cell population but without clinical features are not considered to have TS.
 
Phenotypic males are also excluded from the diagnosis of TS, regardless of karyotype
patient of turner syndrome with her mom
 

 

History

-Identified in 1928
-by Dr. Henry H. Turner
-chromosomal mutation of turner syndrome discovered in 1959

 Incidence-1/2500 live birth

                   -About  99%  45X conception abort                 spontaneously and 1 in 15 spontaneous abortions has 45 X karyotype

 

Clinical features

External appearance

FACIES-Micrognathia,Epicanthal folds,low-set, rotated and /or deformed ears,Fish like mouth, Narrow high arched palate, Ptosis and strabismus.
 
NECK- Short and broad, Hairline on the back is low, Webbing of the neck (25% to 40%) of cases.
 
 
Chest-Shield like Square, Microthelia Inverted nipple, Areolaes are widely spaced.
 
Hand and feet- Congenital lymphedema of hand and the feet,Puffiness in the dorsum of the fingers,Short fourth metacarpals(50%).


 

Sexual infantilism

Genital tract and external genitilia are female in character but immature.
 
Ovaries are fibrous streak.
 
Although streak gonads  are the rule  exceptions has been noted 
 
Plasma FSH levels Elevated in those aged 2 days to 4 years
 
Decreased to high normal values between 5 and 10 years of age
 
After 10 years rose again to castrate range
 

CARDIOVASCULAR MANIFESTATIION

-Cardiovascular anamolies present in20%-50%cases
-Affect left side of the heart

               - coarctation of arota -11%

               - bicuspid arotic valve-16%

                - aoratic stenosis

-BAV is associated with aortic wall abnormalities-ascending aortic dilation, aneurysm formation, and aortic dissection.
 
-cardiovascular failure almost always demonstrate obstructed jugular lymphatics with nuchal cystic hygromas.
 
-Postnataly these hygromas resolve as the lymphatics open later in gestation, but residual webbing of the neck predicts defects such as bicuspid aortic valve (BAV) 
 
-Other anamolies-Partial anomalous pulmonary connection  and persistent left superior vena cava.
- Adults with TS have a high prevalence of electrocardiographic conduction and repolarization abnormalities.
 
-Systemic hypertension is common  and therefore may be the most important treatable risk factor for aortic enlargement and dissection
 

 

Metabolic  Manifestations

-Insulin secretory defect is present in 50%of cases of TS  leading to IGT or Diabetes.
 
-Dyslipidemia with increased LDL and Tg levels
 
-Hypertension is present  in 50% of patients
 
-TS are increased risk for atherosclerosis 
 

 

Lymphatics

 
-The lymphedema seen at birth usually resolves by 2 yr of age without therapy.
 
-lymphedema may occur or reoccur at any age and may be associated with the initiation of salt-retaining therapies such as GH or estrogen.
 
-Treatment- Complete decongestive     physiotherapy.

   -a four-step process involving skin and nail care.

    -massage for manual lymph drainage, compression bandaging, and a subsequent remedial exercise regimen 

 
 
 
 
 

Redundant Nuchal Skin (Panel A) and Puffiness of the Hands (Panel B) and Feet (Panel C) in Turner's Syndrome


 

Urinary system

-Congenital malformations of the urinary system are seen in  30–40% of patients
 
- collecting-system malformations-(20%)
 
- horseshoe kidneys (10%)
 
- malrotation and other positional abnormalities (_5%).
 
- Structural malformations of the kidney occur more frequently in 45X TS, whereas collecting- system malformations occur more frequently in those with mosaic/structural X karyotypes .
 
- All girls with TS should have a renal ultrasound  performed at diagnosis

EYE 

-Abnormalities of the external ocular adnexa- epicanthal folds, ptosis, hypertelorism, and upward slanting palpebral fissures is common.
 
-Red-green color deficiency is present in 8% of the population.
-
strabismus and hyperopia occur in 25–35% , putting them at high risk for amblyopia.
 
- children with TS should be evaluated by a pediatric ophthalmologist at 12–18 months of age .

EAR

-External ear-Low set, malrotated, deformed
 
-In young girls - high prevalence of OM that may result from an abnormal relationship  between the eustachian tube and middle ear,which can lead  conductive hearing .
 
- In adulthood -progressive sensorineural hearing loss 
 
-In young girls –at least annual surveillance for middle ear effusions until at least 7–8 yr of age, and longer for those with a history of OM
 
-In older girls and women with TS with no history of hearing loss, audiological surveillance is warranted every 2–3 yr

 

COGNITIVE FUNCTION

-Most people with Turner's syndrome have normal intelligence
 
-The risk of mental retardation is increased especially  in patients with  a ring (X) chromosome (30 percent)
 
-Approximately 70 percent of patients with Turner's syndrome have learning disabilities affecting nonverbal perceptual motor and visuospatial skills.
 
-Orthodontics
 
-Distinct craniofacial features - flattened cranial base angle, a marked reduction in posterior cranial base length, and a retrognathic face 
 
-The maxilla is narrow with a high, arched palate, whereas the mandible tends to be wide and micrognathic
 
-Girls with TS are also at greater risk for root resorption, which can lead to tooth loss, especially during orthodontic treatment
 
- recommendation-all girls with TS see a pediatric dental specialist  by the age of 2 yr and an orthodontist no later than age 7 yr
 
 

Autoimmunity

-Individuals with TS  have increased risk for autoimmune thyroiditis and celiac disease(4-6%)
-Screening protocol
- Autoimmune thyroid disease- screening annually  with a TSH and T4 from 4 yr of age.
- celiac disease -Periodic screening should begin at age 4 and be repeated every 2–5 yr.

Skin

-An increased number of acquired melanocytic nevi is seen in but the risk for melanoma does not appear to be increased .
-Repeated propensity towards keloid formation is present.

Skeletal system

- Short stature
- most common clinical feature of TS.
- Much of the deficit in height is caused by haploinsufficiency of the short-stature homeobox- containing gene (SHOX) located within , pseudoautosomal region of the X chromosome .
- Average adult stature  is 20 cm shorter than their target height
-The mean final height is 142-147 cm
 
 
The typical growth pattern  is mild intrauterine growth retardation, slow growth during infancy, delayed onset of the childhood component of growth, growth failure during childhood, and the absence of a pubertal growth spurt.
The ratio of sitting to standing height is frequently increased and reflects greater retardation in growth of long bones
 
Other developmental abnormalities -short neck, cubitus valgus, genu valgum, and short fourth metacarpals.
Madelung deformity of the wrist, although often mentioned in connection with TS, is actually rather infrequent
Infants with TS have an increased risk of congenital hip dislocation.
Girls with TS have higher risks (10-20%)of scoliosis and kyphosis .
 

COGNITIVE FUNCTION

-Most people with Turner's syndrome have normal intelligence.
-The risk of mental retardation is increased especially  in patients with  a ring (X) chromosome (30 percent).
-Approximately 70 percent of patients with Turner's syndrome have learning disabilities affecting nonverbal perceptual motor and visuospatial skills.
 
 

Prenatal diagnosis

    ultrasound findings sugestive of TS. –

-Increased nuchal translucency
-presence of cystic hygromas
-coarctation of aorta and/or left-sided cardiac defects, brachycephaly, renal anomalies.
- polyhydramnios, oligohydramnios, and growth  retardation .
-Abnormal triple or quadruple maternal serum

 screening (-fetoprotein, human chorionic gonadotropin,

  inhibin A, and unconjugated estriol) 

 
 
 

Indications for karyotype

  The diagnosis of TS should be considered in any female with unexplained growth failure or pubertal delay  and any constellation of the following clinical findings:

-edema of thehands or feet, nuchal folds,
-leftsided cardiac anomalies,especially coarctation of the aorta or hypoplastic left heart,
-low hairline, low-set ears, small mandible,
-short stature with growth velocity less than the 10th percentile for age, markedlyelevated levels of FSH,
-cubitus valgus, nail hypoplasia,hyperconvex uplifted nails, multiple pigmented nevi.
 
-Characteristic  facies, short fourth metacarpal, high arched palate,
-chronic otitis media (OM)

Karyotype versus Phenotype in Turner Syndrome

-There is some correlations but karyotypes are not predictive of what any particular girl with TS will have
 

45XO

- most common and severest phenotype   (highest incidence of cardiac, renal   abnormalities and other dysmorphic   features)
 

45XO/46XX

 -Some cells have normal XX and some have XO (often called a mosaic pattern as two distinct cell lines).

                -Generally the least severe phenotype.

                -Increased mean height and spontaneous puberty in up to 40%.

46Xi(Xq)

Increased risk of autoimmunity esp thyroid and inflammatory bowel disease and deafness. Structural problems uncommon
 

46Xr(X) Ring Chromosome

              -Spontaneous periods in 33%

              -Congenital abnormalities uncommon

              -Intellectual dysfunction in those with a small ring chromosome

Turner syndrome karyotype
 

 

Aim of Therapy

-Augmenting  stature
 
-Correcting somatic anomalies
 
-Inducing secondary sexual characteristics and menses
 
-Counseling
 
 
 
 

Growth-promoting therapy

-Girls with TS generally have a normal GH secretory pattern 
 
-Provocative GH testing should be performed only in those whose growth is clearly abnormal relative to that expected for TS, determined by Ts specific growth curves(LYON GROWTH CURV)
 
- Administration of  human GH increases growth rate and augments final height by a mean of 5 to 10 cm
 
 
 
 

Growth hormone 

 
-Indicated when the patient’s height falls below -2SD   on the growth curve
 
-Growth hormone therapy is  continued until the growth rate falls to less than 2cm/yr or the bone age exceeds 14 years
 
-Usual dose is 0.375mg/kg/week in seven divided doses
 
-For girls below 9 yr of age start with GH alone
 
-In older girls, or those with extreme short stature start with higher doses of GH and oxandrolone 
 
-The dose of oxandrolone  is  0.05 mg/kg/d  or less                                                                                                                                                          

Growth hormone

Factors predictive of taller adult stature

 
-Relatively tall height at initiation of therapy
 
-tall parental height
 
- young age at initiation of therapy
 
- long duration of therapy
 
- high GH dose
 
 
 

Puberty induction

 
-Before initiation of estrogen therapy, serum gonadotropin levels should be determined to exclude the possibility of delayed spontaneous pubertal development.
 
-Estrogen replacement started at the age of 12 yr permit a normal pace of puberty without interfering with the positive effect that GH has on final adult height .
 
-Transdermal and injectable depot forms of estradiol may be more physiological alternatives than oral estrogens
 
 

Turner Syndrome – mortality

-Overall mortality was increased compared to the general population (standardised mortality rate (SMR) 2.86 ~ almost 3 times the risk of dying)
 
-There was a karyotype risk with

       XO       SMR=4.08

       isoXq       SMR= 3.86

       other karyotype     SMR = 2.1

 
 

Commonest causes of death

       Congenital abnormalities (probably mainly   cardiac)

      Coronary artery disease

      Metabolic/ endocrine (eg inadequate HRT)

 
-DIABETES MELLITUS was a contributing cause of death in 22% of cases.
 
 
 
© article is written by- DR.PRAVEEN RAMACHANDRA 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
© DR. PRAVEEN RAMACHANDRA
womenhormone@gmail.com, womenhormone@rediffmail.com