chromosomal abnormalities Flashcards
define chromosomal investigations?
karyotypes
produced by cutting and pasting chromosome pictures
systemically organised set of chromosomes
two main classifications of chromosomal abnormalities
numerical - number of chromosome
structural - physical change to one of more chromosome
what 3 autosomal trisomy are viable in pregnancy?
trisomy 21 - downs syndrome
trisomy 18 - Edwards syndrome
trisomy 13 - pataus syndrome
downs syndrome characteristics
intellectual disability
infertility
hear disorders
eye disorders
Edwards syndrome characteristics
low birth weight.
small head and jaw.
an unusual-looking face and head.
unusual hands and feet with overlapping fingers and webbed toes.
problems with feeding, breathing, seeing and hearing.
pataus syndrome charateristics
Uncommon
Polydactyly
what is used to visualise chromosome?
FISH
detect abnormalities
cytogenetic localisation of DNA
define robertsonian translocation?
breakage of 2 acrocentric chromosomes/ or close to centromere, form one chromosome, most common b/w 13 and 14
loss of one chromosome
define philadelphia chromosome?
reciprocal translocation b/w chromosomes 9 and 22
encodes for fusion protein (oncogene)
define chromosomal translocation
chromosomes break and stick to other.
define isochromosome
two non-identical chromosomes, one is a combination of two short arms, and the other is a combination of two long arms
define ring chromosome
loss of telomeres OR ends of both arms & formation of a ring structure
what are some indications for karyotyping
prenatal karyotyping
leukaemia
infertility
birth defects
recurent foetal loss
abnormal sexual development
klinefelter syndrome 47, XXY characteristics
symptoms appear after onset of puberty
reduced testosterone
gynecomastia (breast tissue)
intellectual deficiencies
treat w/ hormones and surgery
Turner Syndrome 45, X0 characteristics
short stature
broad chest
low hairline
low set ears
infertility
