Cytogenetics Flashcards
1
Q
constitutional
A
- something present in all or some cells at birth
- this is the opposite of acquired
2
Q
monosomy
A
- loss of one chromosome
- would have a total of 45
3
Q
trisomy
A
- addition of one chromosome,
- would have 47
4
Q
two types of chromosome abnormalities
A
- acquired (cancer related)
- constitutional (birth defects)
5
Q
chromosome abberation is sex chromosomes are…
A
- much less severe than those of autosome
- they can go undiagnosed such as XXX or XYY
6
Q
aneuploidy
A
- abnormal number of chromo
- includes monosomy, trisomy, and tetrasomy
7
Q
polyploidy
A
- abnormal number of sets of chromosomes
- triploidy (69 XXY)
- tetraploidy (92XXYY)
8
Q
the only whole chromosome monosomy compatible with life is that of…
A
a sex chromosome
9
Q
the only trisomies compatible with life are
A
13, 18, 21
-mosaicism occurs but is rare and typically correlated with an abnormal phenotype
10
Q
FISH is useful because
A
-it can detect small changes that can not be seen via karyotyping
11
Q
Edwards sydrome
- chromosomes
- clinical features
- prognosis
- mosaicism
- risk factor
A
- trisomy 18
- prenatal growth deficiency, microcephaly, micrognathia, small mouth, congenital contractures, low set ears, prominent occiput, overlapping fingers, CHD, rocker bottom feet
- 50% die in the first week of life
- mosaicism is rare
- strong maternal age effect
12
Q
Down Syndrome
- chromosomes
- clinical findings
- common association
- things that can shorten life
- recurrence risk
A
- trisomy 21
- strong correlation between increased incidence and advanced maternal age
- flattened facial profile, upward slanting palpebral fissures with epicentral folds, small ears/nose/mouth, protruding tongue, CHD, hypotonia, single palmar crease, clinodactyly
- alzheimers is very common
- presence of cardiac problems or leukemia shortens lifespan
- if the translocation causing the disease is inherited from the mother, the recurrence risk is much higher
13
Q
Patau Syndrome
- chromosomes
- clinical findings
- prognosis
- long term survivors
- familial associations
A
- trisomy 13
- oral-facial clefts, microphthalmia, microcephaly, cardia anomalies, polydactyly of hands/feets, CNs malformations and scalp defects
- over 80% die in the first month, 95% in 6 months
- long term survivors have severe mental delay
- translocation of the long arm of chromosome 13 are common and can be familial
14
Q
Turners syndrome
- genetics
- prenatal
- birth
- childhood
- clinical findings
- chromosomes
A
- 45, X or variant
- Prenatal: common cause of early miscarriage, found by finding increased fluid, swelling, or cystic hygroma in the neck
- Birth: 1/3 of babies are found at birth because of residual signs of prenatal lymphatic block (webbed neck, puffy hands and feet, lowset/rotated ears), other findings include CHD, low posterior hairline, increased carrying angles at the elbows,short fourth metacarpals, and widely spaced nips
- childhood: 1/3 detected here due to short stature
- puberty: 1/3 detected here due to a delay in onset
- clinical fidnings: intelligence is usually normal, short stature treated with growth hormone, delayed puberty treated with estrogen, patients with full turners usually have streak ovaries (absent), pregnancy achieved with IVF and egg donation
- only about half of patients are complete 45, X; mosaicism and chromosome variants are also common (phenotype varies greatly)
15
Q
Kleinfelter Syndrome
A
- 47, XXY
- Clinical features: learning disability, social immaturity, IQ normal range but 10-15 below that of sibs, males are tall with long legs, 50% have gynecomastia, small testes, testosterone treatment is essential for development of secondary sexual characteristics and decrease osteoporosis risk, adults infertile due to low sperm count (preg achieved by obtaining sperm from testis)
- chromosomes: 47,XXY is usual, rarely males with more than two X’s are observed (48,XXXY)
