11/14/24, 10\:39 AM Turner Syndrome

Turner Syndrome

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Turner syndrome\: chromosomal disorder a
Incidence\: occurs in 1 in 2000 baby girls; involves having only one X chromosome (45XO).
Aetiology\: caused by non-disjunction mutation during meiosis; it is a sporadic mutation with no known risk factors. Up to
50% of cases involve mosaic Turner syndrome (some cells 45XO, some 46XX).
Clinical features\:
Short stature\: growth may be normal until age 3; becomes apparent during puberty due to hormone insu
Delayed puberty\: amenorrhoea and infertility caused by primary hypogonadism due to ovarian dysgenesis.
Systemic manifestations\: renal tract abnormalities (horseshoe kidney), cardiac abnormalities (bicuspid aortic valve, aortic
coarctation), recurrent otitis media, autoimmune diseases (hypothyroidism, type 1 diabetes, coeliac disease).
Learning di
Peripheral stigmata\: webbed neck, cubitus valgus, broad chest with widely spaced nipples, short 4th digit, scoliosis, low
set ears, low posterior hairline, high arch palate, increased melanocytic naevi.
Di
of short stature and delayed puberty (e.g., primary ovarian failure, gonadotropin de
de
Investigations\:
Bedside\: blood pressure, growth assessment, urine dip.
Laboratory\: karyotyping (45XO), blood tests for autoimmune complications, hormone tests (FSH, LH, oestrogen), metabolic
pro
Imaging\: echocardiogram, renal tract ultrasound, pelvic ultrasound, DEXA scan.
Other\: pure tone audiometry.
Diagnosis\: con
amniocentesis or chorionic villus sampling.
Management\:
Hormone replacement therapy\:
Oestrogen\: started at age 11 to trigger puberty, maintain uterus health, and bone density.
Progesterone\: started after oestrogen to trigger menarche and maintain menstrual cycle.
Growth hormone\: daily injections from age 5-16 to trigger growth.
Multidisciplinary management\: involving geneticists, endocrinologists, nephrologists, cardiologists, ENT specialists,
obstetricians, psychologists, and general practitioners.
Complications\: autoimmune diseases, recurrent otitis media and glue ear, increased risk of UTIs, osteoporosis,
hypertension, higher rates of type 2 diabetes and hyperlipidaemia.
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Introduction

Turner syndrome is a chromosomal disorder a
stature and underdeveloped ovaries.
Females with Turner syndrome are born with only one X chromosome instead of the usual two X chromosomes. Turner
syndrome occurs in 1 in 2000 baby girls.
1

Aetiology

The X and Y chromosomes are the sex chromosomes, with females having XX sex chromosomes and males having XY
sex chromosomes.
In Turner syndrome, one X chromosome is missing, so the genotype is referred to as 45XO or monosomy X. This is most
commonly caused by a non-disjunction mutation when a pair of chromosomes fail to separate during meiosis. It is a
sporadic mutation meaning it isn’t inherited, and there are no known risk factors.
1
Figure 1. Karyotype in Turner syndrome
with only one X chromosome in the lower
right (45 XO).
Up to 50% of patients with Turner syndrome have mosaic Turner syndrome meaning some cell lines have the 45XO
genotype and some have the normal 46XX genotype. This means patients with mosaic Turner syndrome will have some
but not all phenotypic features, so their management needs to be considered individually.
1
It is important to note that Turner syndrome a
are a
1

Clinical features

A diagnosis of Turner syndrome should be suspected in any girl with short stature or delayed puberty.
2

Short stature

Women with Turner syndrome reach approximately 20cm less than average female height without treatment during
childhood.
It is important to note that growth may be normal until three years old, as growth in this stage of development is driven
primarily by nutrition. During childhood, the growth rate may slow and short stature becomes very apparent during
puberty when they fail to undergo normal pubertal growth spurts. This is a result of hormone insu
ovarian dysgenesis.
1

Delayed puberty

Girls with Turner syndrome are commonly identi
their peers. Amenorrhoea and infertility in Turner syndrome are caused by primary hypogonadism due to ovarian
dysgenesis.
The degree of ovarian dysfunction is variable, particularly with mosaic Turner syndrome, and therefore, some girls with
Turner syndrome may undergo normal menarche and adrenarche.
1

Systemic manifestations

Systemic manifestations of Turner syndrome include\:
3
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Renal tract abnormalities\: the most pathognomonic being a horseshoe kidney (when the kidneys remain fused at the
inferior pole and fail to ascend)
Cardiac abnormalities\: most commonly bicuspid aortic valve or aortic coarctation (narrowing of the aorta)
Recurrent otitis media and conductive hearing loss
Autoimmune disease\: hypothyroidism, type one diabetes mellitus, coeliac disease
Learning di
Most girls with Turner syndrome have good language and reading skills but may experience behavioural and social
di
4

Clinical examination

In the context of suspected Turner syndrome, a thorough examination is required. This includes a full cardiovascular
examination and growth assessment.
On general examination, peripheral stigmata of Turner syndrome include\:
3
Webbed neck (Figure 2)
Cubitus valgus (a wide carrying angle)
Broad chest with widely spaced nipples
th
Short 4 digit
Scoliosis
Low set ears
Low posterior hairline
High arch palate
Increased number of melanocytic naevi
Figure 2. A teenage girl with Turner syndrome and a webbed neck
On cardiovascular examination,
3
Radio-femoral delay
Blood pressure\: hypertension with a gradient between the upper limb and lower limb blood pressure
Murmur\: ejection systolic murmur heard loudest on the back at the inferior tip of the left scapula
Clinical features of Turner syndrome which may be seen in the neonatal period include\:
1,4
Neonatal peripheral lymphedema\: can cause short and curved nails
Cystic hygroma
Stigmata of Turner syndrome (webbed neck, cubitus valgus and low-set ears) may be identinewborn physical
examination (NIPE)
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Di

Noonan syndrome is the main di
disorder also presents with short stature, wide neck and associated cardiovascular defects.
However, Noonan syndrome is caused by an autosomal dominant mutation of the PTPN11 gene, and it can a
or females.
5
Other important di
6
Other causes of primary ovarian failure\: chemotherapy or autoimmune ovarian failure
Gonadotropin de
grows near the pituitary) or Kallmann syndrome (syndrome pathognomonic of delayed puberty and impaired sense of
smell)
Functional gonadotropin de

Investigations

Bedside investigations

Relevant bedside investigations include\:
1,3
Blood pressure\: there may be hypertension secondary to cardiovascular or renal disease
Growth assessment\: height and weight should be plotted on a growth chart so the response to growth hormone
therapy can be monitored over time
Urine dip\: assesses for complications of renal tract abnormalities such as a urinary tract infection (raised leukocyte
esterase and nitrites will be seen)

Laboratory investigations

Relevant laboratory investigations include\:
1,3
Karyotyping\: chromosomal analysis will identify the 45XO mutation
Blood tests to screen for autoimmune complications\: thyroid function tests (hypothyroidism), blood sugar (type one
diabetes), anti-TTG and IgA to screen (coeliac disease)
Hormone tests\: FSH, LH and oestrogen to identify primary hypogonadism secondary to ovarian dysgenesis (high FSH
and LH and low oestrogen will be seen)
Metabolic pro
more common in adults with Turner syndrome

Imaging

Relevant imaging investigations include\:
1.3
Echocardiogram\: screen for bicuspid aortic valve and aortic coarctation. Further imaging including cardiac MRI may be
required
Renal tract ultrasound\: identify structural abnormalities of the renal tract
Pelvic ultrasound\: used to check for the presence of the uterus which will a
future
DEXA scan\: to identify osteoporosis

Other investigations

Other relevant investigations include\:
1.3
Pure tone audiometry\: screen for a conductive hearing loss

Diagnosis

Turner Syndrome is diagnosed via karyotyping, which shows a missing X chromosome.
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Karyotyping is usually performed after a detailed history and examination. Most commonly, Turner syndrome is diagnosed
in late childhood, but Turner syndrome may be suspected on prenatal ultrasound scans when the following are seen\:
1
Horseshoe kidney
Aortic coarctation
Fetal lymphedema
If Turner Syndrome is suspected in-utero, amniocentesis or chorionic villus sampling can be performed to allow for
karyotyping of the fetal chromosomes.
1

Management

Hormone replacement therapy is the mainstay of management for Turner syndrome.
2

Hormone replacement therapy

Oestrogen
Oestrogen replacement therapy is started at age 11, and the dose is increased slowly to mimic the normal physiological
process of puberty. Oestrogen can be given as a gel, tablet or patch.
The role of oestrogen is to\:
Trigger breast development
Maintain uterus health
Maintain bone mineral density to prevent osteoporosis
Progesterone
Progesterone replacement therapy is started after oestrogen replacement therapy. It can also be given as a tablet or
patch. The role of progesterone is to trigger menarche and maintain a normal menstrual cycle.
Both oestrogen and progesterone are given until around age 50 when sex hormones naturally decrease when a woman
enters the menopause. Hormone replacement can continue beyond 50 after considering the risks and bene
Fertility and pregnancy
Women with Turner Syndrome experience infertility secondary to ovarian dysgenesis. However, they have a normal
uterus and vagina, so they can become pregnant with the help of in vitro fertilisation (IVF).
Women with Turner Syndrome who become pregnant must be monitored in specialist antenatal clinics due to the
additional physiological strain pregnancy may place on the heart and kidneys.
Growth hormone
Growth hormone is given as a daily injection from age 5-16 to help trigger growth. On average, patients with Turner
syndrome undergoing growth hormone replacement therapy grow 5cm taller than those without.

Multidisciplinary management

A multidisciplinary management approach is required in Turner syndrome\:
2
Geneticist\: involved in the diagnosis of Turner syndrome
Endocrinologist\: manage hormone replacement therapy and autoimmune disease
Nephrologist\: monitor blood pressure and manage any complications of renal tract abnormalities
Cardiologist\: monitor and treat cardiovascular abnormalities
ENT\: monitor and treat otitis media and conductive hearing loss
Obstetrician\: in vitro fertilisation and close monitoring during pregnancy
Psychologist\: support with behavioural problems and the mental health consequences of having a chronic condition that
a
General practitioner\: often the
present with short stature or delayed puberty.
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Complications

Complications of Turner syndrome include\:
1,2
Autoimmune diseases\: hypothyroidism, type one diabetes mellitus and coeliac disease
Recurrent otitis media and glue ear\: may lead to a conductive hearing loss
Increased risk of urinary tract infection\: due to structural abnormalities of the urinary tract
Osteoporosis secondary to low oestrogen\: oestrogen promotes osteoblastic activity required to produce bone
Hypertension secondary to renal and cardiac abnormalities\: hypertension must be managed e
risk of cardiovascular complications in later life (e.g. stroke or aortic dissection)
Higher rates of type two diabetes mellitus and hyperlipidaemia. This is re
syndrome, for which the most common cause of death is non-congenital cardiovascular disease, including coronary
artery disease and stroke.

References

UpToDate. Clinical manifestations and diagnosis of Turner syndrome. Published in 2022. Available from\: [LINK]
Patient.info. Turner syndrome. Published 2021. Available from\: [LINK]
BMJ Best Practice. Turner’s syndrome. Published 2021. Available from\: [LINK]
NHS Health. Turner syndrome. Published 2021. Available from\: [LINK]
Patient.info. Noonan syndrome. Published in 2016. Available from\: [LINK]
GP notebook. Delayed puberty. Published in 2021. Available from\: [LINK]

Image references

Figure 1. Unknown author. 45,X. License\: [Public domain]
Figure 2. Imen Mehri Turki.Preoperative webbed neck in Turner syndrome. License\: [CC BY]

Reviewer

Dr Kayleigh Weedon
General Practitioner
Honorary Associate Professor | University of East Anglia

Attention De
Autism Spectrum Disorder (ASD)
Biliary Atresia
Bronchiolitis
Cerebral Palsy

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