Cytogenetics I- Lecture 9/16/21 Flashcards
How many chromosomes do we have?
46
Normal Karyotype
46, XX or XY
Karyotype nomenclature
Number of chromosomes, sex chromosomes, any additional abnormaloties
Numerical Karyotype changes
Changes in the number of chromosomes
Structural changes in Karyotype
Any rearrangement of chromosomes
P arm
Short arm
Centromere
Where the chromosomes line up
Q arm
Long arm of a chromosome
Metacentric
Centromere in the middle
Submetacentric
Towards one Side
Down syndrome nomenclature
47, XX/XY, +21
Done syndrome features
Trisomy 21, flat facial features, upslanted palpebral fissures, single palmar crease
Edwards syndrome karyotype
47, XX/XY, +18
Features of edwards syndrome
Macrocephaly, micrognathia, congenital contracture low set ears, only 5% survive longer than a year
Patau syndrome karyotype
47, XX/XY, +13
Features of Patau syndrome
Scalp defects, microcephaly, microphthalmia, only 5% survive past 6 months
Turner syndrom
Lymphedema, bicuspid aortic valve, short stature, gonadal regression
Turner syndrome karyotype
45 X
Klinefelter syndrome
Tall stature and long limbs, learning differences, small testes, infertility
Klinefelters syndrome
47, XXY
Pseudoautosomal region
Not inactivated region on X chromosome, region that recognizes the Y chromosome in male meiosis
Nondisjunction
The failure of one or more of homologous chromosomes or sister chromatids to separate normally
Trisomic rescue
Can get rid of one of the extra chromosomes, but can result in uniparental disobey
Nondisjunction in meiosis I
Leads to heterodisomy, two different chromosomes from same parent
Nondisjunction in meiosis 2
Winds up with two of the same chromosomes from one parent, isodisomy
