Question

Describe the karyotype 46, XY, r (7) (p22q36) considering

i) chromosome number (euploid or other),

ii) genetic gender,

iii) structural aberration type and

iv) location(s) of structural aberration.

Answer 1

Answer: iv) location(s) of structural aberration

Comments: Karyotype/Karyotyping: Process of arranging the chromosomes in order to determine any chromosomal change (change in chromosome number due to deletion, duplication translocation or inversion) in an individual. This change in chromosome number is due to non-disjunction of chromosomes during meiotic division. Every chromosome has two arms P-arm and q arms. The location of gene on chromosome is designated with chromosome number then p/q and lastly the position. In the above question the 46, XY, r (7) (p22q36); r= ring chromosome, 7= 7th number of chromosome, p22= breaking point of P arm of region 2 of band 2 similarly for q36= breaking point of q arm at region 3 of band 6. In this translocation the chromosome no.7 break at two points P22 and q36 and joined to form a ring (ring chromosmome-7) due to that inversion of gene segment takes place. The effected individual characterised with growth failure, mental retarded etc.