Are variations in length of Y chromosome due to structural changes?

Abstract

Earlier research on the causes of extreme variation in the length of the Y chromosome has given ambiguous results. The development of the fluorescence technique has made it possible to study this chromosome in more detail. The results reported here indicated that extremely short and extremely long Y chromosomes result from structural changes, not from differences in amount of contraction. It is impossible, without study of further material, to draw conclusions on the clinical characteristics associated with aberrations in the length of this chromosome.