In approximately 90% of the patients with the DiGeorge syndrome, the congenital disorder is caused by a classic de novo heterozygous deletion of approximately 2.5 mb in length spanning chromosome 22q11.2 low-copy repeats (LCR22) A and D, as shown in blue. Less than 10% of the patients with this syndrome carry the critical 1.5-mb deletion between LCR22 A and B. Shown in red are deletions that were identified in 14 patients who were affected by congenital anomalies of the kidney and urinary tract among the 2080 patients who were tested. According to the megabase coordinates for the Human Genome 19 release, the proximal and distal breakpoints for the chromosome 22q11.2 deletions that were identified in the patients are as follows: P1, 18.88 to 21.47 mb; P2, 18.89 to 21.47 mb; P3, 20.73 to 21.46 mb; P4, 21.02 to 22.47 mb; P5, 21.05 to 21.47 mb; P6, 21.06 to 21.47 mb; P7, 21.06 to 21.46 mb; P8, 21.06 to 21.46 mb; P9, 21.07 to 21.46 mb; P10, 21.08 to 21.47 mb; P11, 21.09 to 21.47 mb; Patient 1 from the replication cohort (RP1), 18.88 to 21.46 mb; RP2, 20.74 to 21.46 mb; and RP3, 20.74 to 21.46 mb. The deletion between LCR22 C and D defines the smallest region of overlap for congenital kidney disease among patients with 22q11.2 deletions.