GIM 6 - chromosomal basis of inheritance Flashcards
what is cytogenetics
study of chromosomes
what is autosomes
chromosome 1-22
23 = sex chromosomes
when is chromosome most visible?
in metaphase in mitosis
at what phases do G-banding test at ?
metaphase in mitosis
at what phases do molecular cytogenetic test at ?
all phases and stages
what does karyotype mean?
using G-banding and sort out from the largest chromosome to the smallest
what are the telomere
the endings of the chromosome bands
what are the 2 large subdivision for chromosome bands
P & Q
how many smaller subdivisions are there for the p band
2
how many smaller subdivisions are there for the q band
3
what are the different types of cytogenetic abnormality
numerical & structural
what does diploidy mean
2 copies of each chromosome
what does aneuploidy
gain (trisomy) or less (monosomy)
what does aneuploidy
gain whole sets (triploidy or tetraploidy)
what does mosaicism mean
diploidy & aneuploidy
where can numerical abnormality arise
gametogenesis - meiosis, fertilisation, early cleavage
what can increase in maternal age do?
increase aneuploidy
how is meiotic error arise?
chromosome non-disjunction, chromatid non-disjunction
what syndrome can trisomy 18 lead to?
Edwards Syndrome
what are some clinical features for Edwards Syndrome
Head: microcephaly; low set ears; micrognathia; ears low set; cleft lip and palate
Hands & feet: Clenched hands, overlapping fingers; Rockerbottom feet
Severe mental retardation
what are some examples of organ malformation in trisomy 18
umbilical/inguinal hernia
congenital heart disease
congenital kidney abnormalities
what is the cause of patua syndrome
trisomy 13
what causes Turner’s syndrome
45,X
what causes Klinefelter’s syndrome
47,XXY
