Module 9 - Part 1 Flashcards
Case study: What type of genetic testing did the paediatrician order for initial investigation?
Microarray
Case study diagnosis
A chromosomal deletion on the long (q) arm of chromosome 3
- linked to developmental delay
- 30 documented cases worldwide
Numerical chromosomal abnormality
a gain or loss of an entire chromosome
- gain: trisomy
- loss: monosomy
Structural chromosomal abnormality
the gain, loss or rearrangement of genetic material on one or more chromosome
Chromosomal abberations occur in (stat)
1 out of 150 ppl
Breakpoint
region of DNA that has been broken and/or reattached during a rearrangement
Types of chromosome rearrangements (5)
- deletion
- duplication
- inversion
- insertion
- translocation
(leads to gain/loss/rearrangement of genetic material)
Case study results
Arr [hg19] 3q13.12 (107,185,072-117,191,259) X1
hg - human genome assembly 19
3q arm of chromosome 3 band 13.12
bases affected
copy number (should be X2)
3q13.12 Microdeletion syndrome
- deletion approx. 10,006 kb in size (13.12-13.31)
- overlaps w a known micro deletion locus & includes the loss of more than 70 putative genes (potential genes)
In translocation, recombination occurs between
two different (non-homologous) chromosomes
Balanced translocations
May have no impact if they’re balanced & no genetic material is deleted/duplicated
Unbalanced translocations
Homologous chromosomes aren’t fully diploid
Paracentric inversion
Doesn’t include the centromere
Pericentric inversion
Span the centromere
Inversion considerations
may not be problematic to the carrier, however offspring may be affected due to recombination during meiosis/gametoigensis
