Concurrent Loss of Heterozygosity and Mosaic Deletion of 12p13.32pter

Deletions in the short arm of chromosome 12 are the rarest subtelomeric imbalances. Less than 20 patients have been reported to date, and their microdeletions were identified either by FISH or array-CGH without SNP data. Here, we report a patient with a 12p13.32pter mosaic deletion detected by chromosome microarray analysis with loss of heterozygosity (LOH) of the deleted segment in addition to the adjacent distal segment. LOH is indicative of a complex rearrangement, suggestive of mitotic microhomology-mediated break-induced replication.