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Chromosomal Abnormalities (ii) - Coggle Diagram
Chromosomal Abnormalities (ii)
Turner Syndrome (45, XO)
over 95% result in early miscarriage
can be detected on foetal US
oedema in neck, hands or feet
cystic hygroma
incidence = 1 in 2500 in live born girls
features
short stature = cardinal feature, may be the only clinical abnormality in children
lymphoedema in hands + feet
spoon-shaped nails
neck webbing / thick neck
wide carrying angle (cubitus valgus)
widely spaced nipples
CHD
delayed puberty
ovarian dysgenesis - infertility, pregnancy may only be possible with IVF + donated ova
hypothyroidism
renal abnormalities
pigmented moles
recurrent OM
normal intellect in most
tx
GH therapy
Oestrogen therapy to develop secondary sexual characteristics (infertility persists)
only 1 X chromo in 50%
short arm deletion on 1 X chromo in other 50%
Presence of Y chromo sequence may increase risk of gonadoblastoma
incidence doesn't increase with maternal age
recurrence risk v low
Klinefelter syndrome (47, XXY)
1-2 per 1000 live born males
recurrence risk v low
features
infertility (most common presentation)
hypogonadism (small testes)
pubertal development may appear normal (some may benfit from testosterone tx)
gynaecomastia
tall
intelligence usually normal, some may have education/psych problems
Reciprocal translocations
exchange of material between 2 different chromos
balanced
no loss/gain of chromo material
common 1 in 500 in general pop
usually no phenotypic effect unless occurs @ important chromo breakpoints - cognitive difficulties
unbalanced
impair both physical + cognitive development
dysmorphic features
congenital malformations
developmental delay
learning difficulties
in newborn prognosis difficult to predict but effect usually severe
should check parental chromos if de novo or parental cause - indicates recurrence risk
Deletions
usually result in physical abnormalities + cognitive impairment
Cri du Chat syndrome
monosomy 5p
high pitched meowing cry in early pregnancy
parental chromos should be checked
clinical severity varies greatly depending on extent of deletion
DiGeorge syndrome
chromo 22q11 deletion
CHDs, facial dysmorphia, immunodeficiency, developmental delay, learning problems, cleft palate, thymus dysplasia
Williams syndrome
7q11 deletion
mild learning/developmental challenges, high levels of ca in blood + urine, outgoing personality, “elfin” appearance, low nasal bridge