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

Abstract

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.

Variable Phenotypes of Epilepsy, Intellectual Disability, and Schizophrenia Caused by 12p13.33–p13.32 Terminal Microdeletion in a Korean Family: A Case Report and Literature Review

“…To date, approximately 28 reported cases with 12p13.33 microdeletion have been described and are associated with DD/ID and various neuropsychiatric manifestations ( Table 1 ). In these cases [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], the phenotypic features were variable and indistinct, maybe due to the size of the deleted segment. However, there seems to be no correlation between the size of the deleted size and the severity of the reported clinical phenotypes.…”

“…Constitutional deletions involving the distal part of the short arm of Genes 2021, 12, 1001 2 of 11 chromosome 12 (12p13. 33-p13.32) are very rare and have been reported in only 28 cases so far [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]; either inherited [14,15,17] or sporadic [12,16,17,21,23] and identified by conventional karyotyping or chromosomal microarray (CMA). Notably, among the reported cases, the clinical manifestations differed substantially according to the size of the deletion.…”

“…Fine mapping of the subtelomeric regions has become a new strategy for identifying novel genes responsible for DD and/or ID. Constitutional deletions involving the distal part of the short arm of chromosome 12 (12p13.33–p13.32) are very rare and have been reported in only 28 cases so far [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]; either inherited [ 14 , 15 , 17 ] or sporadic [ 12 , 16 , 17 , 21 , 23 ] and identified by conventional karyotyping or chromosomal microarray (CMA). Notably, among the reported cases, the clinical manifestations differed substantially according to the size of the deletion.…”