Chromosomal Disorders Flashcards
Too many (trisomy) or too few (monosomy) copies of chromosome
Aneuploidy
whole multiplies of haploid chromosome
Polyploidy
Genetic material has been lost (deletion) or rearranged
Structural chromosomal abnormality
Most common in cattle
2 chromosomes fuse together near centromere –> less chromosome number, little/ no loss in genetic material;
Reduced fertility
Centric Fusion Translocation
most common centric fusion translocation
1/29 translocation (Robertsonian translocation)
In cattle;
mixing of hemopoietic precursor cells –> establishment of male & female cells in blood of each twin
Freemartinism (XX/XY)
In sheep;
there is no reduction in fertility
Centric Fusion Translocation
Rare in sheep
Reciprocal translocation
Most common in sheep
Freemartinism
Causes reduced fertility in Saanen breed
Centric Fusion Translocation
most common in pigs;
little or no loss of genetic material
Reciprocal Translocation
Most common in horses;
XO mares: infantile uterus; infertile
X chromosome aneuploidy (XD/XXX)
another common chromosomal disorder other than XD
XY sex reversal
female horse + male donkey
Mule
Abnormalities of chromosome pairing at the pachytene stage of meiotic prophase;
little or no spermatozoa; infetile
Males
