genetic changes seminar Flashcards
what is a balanced translocation in chromosome 4 and 8?
chromosome swap pieces - 4p;8p. In balances the short arm of 4 and 8 swap and there is no net loss of genetic material
what is the standard approach for looking at chromosomal imbalances?
chromosome microarray - first line of investigation if there are any unexplained neurodevelopmental problems
what can be seen in array CGH?
loss is on one side and gain on the other and therefore shows cytogenetic localisation, coding (pathogenic) or non (benign), size and region
how large is the change in miscarriage?
likely to be a large DNA change
how would you calculate the size and position of chromosome imbalances?
work out the start and end position
what is an unbalanced 4p;8p translocation?
two types - either part of 4 is missing and a bit of 8 on top or part of 8 missing and some of 4 on top - this results in incorrect amount of material and can cause difficulties with development and health
what results when part of p arm of 4 is missing?
Wolf Hirschhorn Syndrome - learning difficulties, seizures, abnormal brain electrical patterns and small at birth - inherited from either mother or father so siblings can also have
what is a pachytene quadrivalent?
when similar parts of DNA pair i.e in translocation
what is the process of aCGH?
reading raw data from microarray scanner, calculating the red/green fluorescence for each spot and normalisation - correcting bias in the log2 ratio
what is a test for foetus to identify the number of each chromosome?
QF-PCR
after array how is the diagnosis confirmed?
FISH or qPCR and parental studies
what can pachytene quadrivalent in meiosis result in?
unbalanced haploid complement
