Question

11) Compare the following causes of chromosome abnormalities: Deletions, Duplications, Inversions and Translocations.

Answer 1

Structural abbreiations occurs due to loss of genetic material or rearrangment in the location of genetic material. These include deletions, duplications, inversions, ring formation and translocation.

Deletions- A portion of the chromosome is missing or deleted known disorder include Wolf-Hirschhorn syndrome which means partial deletion of short arm of the chromosome 4.

Duplications- A portion of the chromosome is duplicated, resulting in extra genetic material known disorders include charvot-marie-tooth disease type 1A which may lead may caused due to duplication of gene encoded peripheral myelin protein 22 on chromosome 17.

Inversions- A portion of the chromosome has broken off, turned upside down and re attached therefore the genetic material is inverted.

Translocations- When a portion of one chromosome is transferred to another chromosome. This is of two types- Reciprocal translocation-segments of two different chromosomes have been exchanged. Robersonian translocation- an entire chromosome has attached to another at the centromere, these occurs only with chromosomes 13,14,15,21 and 22.