Clinical Presentation of Chromosomal Disorders 8/13
1. centromere: constricted portion of a chromosome necessary for proper cell division
2. what is chromatin: chromsomes packaged with histones
3. types of chromosomal abnormalities: numerical
structural
germline
mosaic
4. numerical abnormality: aneuploidy can occur in meiosis or mitosis
5. structural abnormality: translocation
inversion
deletion/duplication
6. germline abnormalities: present in all cells and present from conception
7. mosaic abnormalities: -may be in all or only some
-some contain it while others dont (cells)
- blood test isnt necessarily reflective because it may be in other tissues
1/4
, 8. chromosomal testing: karyotype
FISH
SNP microarray
9. karyotype: cells are arrested in metaphase and stained
10. most common autosomal conditions: trisonomy 21, 18, 13
11. most common sex chromosome conditions: Turner (45X) and Klinefelter (47 XXY), XYY, XXX
12. why is it survivable for trisonomy of those chromosomes: they are smaller/hold less
genes
13. Trisomy 21: 1:700 live births
most common chromosomal disorder
multiple organ malformations
intellectual disability
14. recognizeable features of trisomy 21: flat facial profile
epicanthal folds (extra skin in eyes)
brushfield spots (dots surrounding iris)
2/4
1. centromere: constricted portion of a chromosome necessary for proper cell division
2. what is chromatin: chromsomes packaged with histones
3. types of chromosomal abnormalities: numerical
structural
germline
mosaic
4. numerical abnormality: aneuploidy can occur in meiosis or mitosis
5. structural abnormality: translocation
inversion
deletion/duplication
6. germline abnormalities: present in all cells and present from conception
7. mosaic abnormalities: -may be in all or only some
-some contain it while others dont (cells)
- blood test isnt necessarily reflective because it may be in other tissues
1/4
, 8. chromosomal testing: karyotype
FISH
SNP microarray
9. karyotype: cells are arrested in metaphase and stained
10. most common autosomal conditions: trisonomy 21, 18, 13
11. most common sex chromosome conditions: Turner (45X) and Klinefelter (47 XXY), XYY, XXX
12. why is it survivable for trisonomy of those chromosomes: they are smaller/hold less
genes
13. Trisomy 21: 1:700 live births
most common chromosomal disorder
multiple organ malformations
intellectual disability
14. recognizeable features of trisomy 21: flat facial profile
epicanthal folds (extra skin in eyes)
brushfield spots (dots surrounding iris)
2/4
