Turners syndrome

Question 1

Define Turners syndrome

Answer 1

45 XO - condition only affecting females and occurs when one f the X chromosomes is missing or partially missing

Question 2

What is the relevant epidemiology of turners syndrome?

Answer 2

Very low risk
Not associated with maternal age
Affects 1 in 2,500 live births
Not inherited

Question 3

What is the relevant genetics underpinning turners syndrome?

Answer 3

Loss or abnormality of the second ( commonly paternal) X chromosome = not functional.
Typically, a non-dysfunction mutation

Question 4

What are the three potential karyotypes of turner syndrome?

Answer 4

1. Most commonly 45 XO - due to non disjunction in meiosis in gametogenesis.
2. Mosaicism - error following conception, mitosis non-dysjunction
3. Only part of chromosome missing - can be complete or mosaic.

Question 5

What are the affects of turner syndrome on hormones?

Answer 5

Inc rate of loss of eggs -> non-functional fibrosis streak ovaries -> hypogonadism with low estrogen ->
High FSH and LH (due to lack of negative feedback mechanism)

Question 6

What are the complications of turner syndrome?

Answer 6

1. S HOX genes -> only single copy leads to short stature
   2 Cardiovascular - preductal coarctation of the aorta, bicuspid aortic valve
2. Horshoe kidney - fusion of both kidneys
3. Lymphatic abnormalities
4. Skeletal abnormalities
5. Inc risk of type 2 DM and hypothyroidism, otitis media

Question 7

How does turner sydrome present in infants?

Answer 7

Swelling - due to build up of lymph
Cystic hygroma - decreases with age -> leads to neck webbing
Lower extremity cyanosis due to cardiovascular effects
Horseshoe kidney - recurrent UTI

Question 8

What are the symptoms of Turner syndrome in children/teenagers?

Answer 8

Low set ears
Neck webbing
Broad flat chest with widely spaced nipples
Arms turn outward - cubitus valgus
Short stature
Spoon shaped nails
Streak ovaries -> primary amenorrhea (no breast by age 13yrs, no menarche by age 15yrs) = infertility or delayed puberty

Question 9

How is turner syndrome diagnosed?

Answer 9

Karyotype analysis - CVS or amniocentesis before birth

Question 10

What investigations might you do for a child with turner syndrome?

Answer 10

Pelvic ultrasound - reproductive organs
Echo - cardiac abnormalities such as aortic coarctation and bicuspid aortic valve
Audiometry - due to frequent otitis media
Bone age assessment - help estimate the adult height and timining of puberty
Renal ultrasound - screen for renal anomalies -> horseshoe kidney or unilateral renal agenesis.

Question 11

What is the common management plan in Turners syndrome?

Answer 11

Growth hormone replacement therapy - at diagnosis - to maximise height potential
Oestrogen replacement therapy - pubertal onset to stimulate secondary sexual characteristics, start low dose and inc, progestin once bleeding for regular menses and prevent endometrial hyperplasia
Cardiovascular - HTN management
Fertility counselling
DEXA - baseline and on oestrogen therapy
Psychosocial support - inc risk of learning difficulties and social adjustment problems.