Chromosomal Stabilisation by a Subtelomeric Rearrangement Involving Two Closely Related Alu Elements

We have characterised a subtelomeric rearrangement involving the short arm of chromosome 16 that gives rise to α-thalassaemia by deleting the major, remote regulatory element controlling α-globin expression. The chromosomal breakpoint lies in an Alu family repeat located only ~105 kb from the 16p subtelomeric region. The broken chromosome has been stabilised with a newly positioned telomere acquired by recombination between this 16p Alu element and a closely related subtelomeric Alu element of the Sx subfamily. It seems most likely that this abnormal chromosome has been rescued by the mechanism of telomere capture which may reflect a more general process by which subtelomeric sequences are normally dispersed between chromosomal ends.