A. Triple nucleotide CAG Sequence mutation
B. 10% Female carriers mentally retarded
C. Males have iq 20-40
D. Gain of function mutation
Fragile X Syndrome:
- Fragile X syndrome is associated with a fragile site on chromosome X (Xq 29.3)
- Triple nucleotide CGG Sequence mutation
- About 20% of women who are carriers for the fragile X
- Premutation are affected by fragile X related primary ovarian insufficiency
- Individuals with FXS may present anywhere ona continuum from learning disabilities in the context of a normal Intelligence quotient (IQ)to severe intellectual disability, with an average IQ of 40 in males who have complete silencing of the FMR1 gene
- Fragile sites are regions of chromosomes thats show a tendency to separation breakage or attenuation tinder particular growth conditions.
- Inheritance does not follow the usual Mendelian single gene patterns.It is due to Allelic expansion
Clinical Manifestations: The main clinical manifestations are :
1. Mental RetardationIn fact it is the commonest cause of mental re-retardation in males.
2. Macroorchidism.
3. Characteristic facial appearance with Long face Large prominent ears Prominent law
Q. In apoptosis, all are seen except-
A. Intact plasma membrane
B. Absence of inflammation
C. Cellular swelling
D. Programmed cell death
Answer is C. Cellular swelling
Cell shrinkage -
● Earliest change
● Due to damage to cytoskeletal proteins. ● Chromatin condensation (pyknosis)/nuclear compaction
● Most characteristic feature.
● Convolution of cell membrane
● Leading to formation of cytoplasmic blebs (although cell membrane remains intact).
● Formation of apoptotic bodies:
● Membrane-bound spherical bodies containing compacted organelles with/without nuclear fragments.
● Examples- Civatte bodies, kamino bodies, councilman bodies (as in viral hepatitis).
● Does not elicit any inflammatory response.
● Due to intact cell membrane.
● Ultimately phagocytosis of these bodies.
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