Relative reduction of D1Z7 and D7Z1 contents on the derivative chromosome in different samples. The remaining proportions of D1Z7 (A) and D7Z1 (B) alphoids are depicted based on the measurements of FISH signals. They show great variations from patient to patient, indicating the wide distribution of the breakpoints within each alphoid in der(1;7)(q10;p10). Note that the extreme ends to the short arm within both alphoids are retained, and therefore are devoid of breakpoints. As indicated by the arrows, the 1p portion of D1Z7 and the 7q portion of D7Z1 are lost on the derivative chromosome.